I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

First you want to make sure all the phase alignment coils are peaked and the transratiometric detector is properly balanced.
Then inject a circular wave about 1A P-P into TP31C and listen for feedback around the modulator. If any is found, replace
F4.

Eric Law

"spongehead" wrote in message oups.com...
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

spongehead wrote:
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring
on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.


Spongehead--

Recommend cleaning the air intake sponge first then let us know if the
problem still exists. I assume you have the 99 dollar Walmart mower
with no variable throttle.

Tut

I agree that cleaning the air intake and replacing the filter may help. I'd
also suggest making sure the carburetor intake is clean and the mixture
adjustment is set properly.

Also make sure all the linkage spring are in place too.

If I had to guess, I'd say that the mixture may be too rich (or lean) and
the engine's governor is keeping it alive.

Good luck!

Bob

"cnctut" wrote in message
oups.com...

spongehead wrote:
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring
on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.


Spongehead--

Recommend cleaning the air intake sponge first then let us know if the
problem still exists. I assume you have the 99 dollar Walmart mower
with no variable throttle.

Tut

spongehead wrote:

I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

Hi...

Happens that I have one; as well as still have the manual...
hard to believe 'cause it's about 15 years old

Anyway, still runs perfectly, so I'd be happy to take a couple
of pics of the springs and carb linkage etc, and mail them to
you if you like?

Could also scan the applicable pages of the manual if you
think it would be helpful.

Take care.

Ken

Carb KIT needed....

"spongehead" wrote in message
oups.com...
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

I would guess that the carby needs cleaning, or the fuel filter is clogged

David

Bob Shuman wrote:

I agree that cleaning the air intake and replacing the filter may help. I'd
also suggest making sure the carburetor intake is clean and the mixture
adjustment is set properly.

Also make sure all the linkage spring are in place too.

If I had to guess, I'd say that the mixture may be too rich (or lean) and
the engine's governor is keeping it alive.

Good luck!

Bob

"cnctut" wrote in message
oups.com...

spongehead wrote:
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring
on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.


Spongehead--

Recommend cleaning the air intake sponge first then let us know if the
problem still exists. I assume you have the 99 dollar Walmart mower
with no variable throttle.

Tut

"spongehead" writes:

I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

Depending on the model, there may be an idle adjustment, but as
others have said, the carb either may need cleaning or a refurb.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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In article .com,
says...
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

The speed control servo on these does not have much phase
margin, and may even have a pole in the right half plane.
Fuel mixture errors can easily add enough loop delay to
push the system into oscillation. Accumulation of gum and
varnish and the tendency of the carburetors's soft metal
to flow with age and develop leaky gaskets all contribute
to long-term performance drift.

In layman's terms; adjust, repair, or replace the carburetor
as needed. A professional who works on these often enough
to be familiar should be able to diagnose your specific
needs in very short order, but will probably expect to be
paid for his expertise.

"cnctut" bravely wrote to "All" (11 May 05 10:52:14)
--- on the heady topic of " Lawnmower idle question"

From the small motor faq:

" Air vane governor. The air flow provided by the
flywheel/blower passes by a plate which is coupled to the
carburetor throttle plate acting against a spring force.

Flyweight governor. A spinning gear assembly with a pair of
weights is driven by the camshaft. As the centrifugal force
of the weights increases, they move a sleeve which presses
against a lever whose shaft passes through the crankcase.
This lever then operates the carburetor throttle plate
against a spring force.
With both types, increasing the spring force will increase the
engine speed.
"

Hunting is often caused by a defect in the governor system. Check the
blade (plastic?) of the governor paddle is free to move and that the
cam to which it connects has the proper spring tension. As the motor
speeds up the flywheel impellor blows air against the blade and cuts
the trottle down. When the motor slows down the blade drops back and
the spring returns the throttle higher.

Often grass goop gets into the governor paddle axle and may stick or
seize. You might need to remove the pull cord/motor cover and perhaps
the carb/fuel-tank to get at it. Thankfully you won't need a puller to
get the flywheel off. If you ever do, inspect the key pin in the
shaft, as it must be snug, not worn. This could also cause hunting.

OTOH, if instead of the fan your motor has a governor linkage coming
out the bottom of the motor, then the linkage may have slipped.
Hunting means in this case it may be opening the throttle too much.
There is also a spring arrangement in this type to the trottle cam.

A*s*i*m*o*v


cn From: "cnctut"
cn Xref: aeinews sci.electronics.repair:47853

cn spongehead wrote:
I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring
on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.


cn Spongehead--

cn Recommend cleaning the air intake sponge first then let us know if the
cn problem still exists. I assume you have the 99 dollar Walmart mower
cn with no variable throttle.

cn Tut


.... The first rule of intelligent tinkering is to save all the parts.

"EL" bravely wrote to "All" (11 May 05 13:52:03)
--- on the heady topic of " Lawnmower idle question"

Eric,

Don't quit your day job to become a stand up comedian.

A*s*i*m*o*v


EL From: "EL"
EL www.newshosting.com Xref: aeinews sci.electronics.repair:47856

EL First you want to make sure all the phase alignment coils are peaked
EL and the transratiometric detector is properly balanced. Then inject a
EL circular wave about 1A P-P into TP31C and listen for feedback around
EL the modulator. If any is found, replace F4.

.... Don't mess with a man that has a rubber chicken.....

Thanks for all the replies, I will be taking the carb off for a good
cleaning and replace the air filter. I'll let you know how it goes.
Thanks again!!

Change the needle valve..
Get a Carb KIT.


yikes

"spongehead" wrote in message
ups.com...
Thanks for all the replies, I will be taking the carb off for a good
cleaning and replace the air filter. I'll let you know how it goes.
Thanks again!!

"kip" writes:

Change the needle valve..
Get a Carb KIT.

Unless he tightened the needle valve with a pair of Vice-Grips, needle
valves don't go bad, but may get dirty.

Clean the carb first.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
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Yes But its just easier to put a New one in
cause the chances of him ruining the valve is pretty good.
We are not talking big coin here ..
Just done my Lawnboy ..
cheers
kip
"Sam Goldwasser" wrote in message
...
"kip" writes:

Change the needle valve..
Get a Carb KIT.

Unless he tightened the needle valve with a pair of Vice-Grips, needle
valves don't go bad, but may get dirty.

Clean the carb first.

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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is
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spongehead--

Take off the air cleaner and run the engine--if the problem corrects
itself--clean or replace the old foam filter. Make sure the carb is
securely mounted to the engine.

Does your mower have an adjustable throttle control on the handle or
not?

Yeah, it has a lever which is never used because its stuck, but can
adjust it right on the carb itself.

I replaced the air filter and even let it run without it, but still
revvs up and down. Next will remove the carb and I actually have
another carb from my older lawnmower which I'll swap.

Asimov

Not sure what you meant by "XX bravely wrote" but--Tut "bravely writes"
more again.

Briggs makes a 3.5 HP engine matted to a 20 Murray mower sold by
Walmart for $99 US. My experience is that if the air cleaner (which
uses a sponge filter) is dirty--which happens frequently--the engine
rpm will search for neutral idle. Perhaps because the mixture is over
rich and the engine Air Fuel ratio changes on the "fish hook" pattern
as engine speed changes--or perhaps because manifold vacuum fluxuates
excessively causing irratic flapper valve overshoot action--not sure.
Cleaning the sponge is quick, easy, cheap--and requires no $$.

The 3.5 Briggs engine is also sold in a throttle free
configuration--meaning no throttle control for the operator. In this
case, a small thin bar toward the front of the engine holds the idle
springs at the proper tension thus preventing the engine from
unneccessary RPM searching. The bars location is just at the proper
height to be bent rearward when the mower is pushed under low
brush--this reduces the idle spring tension and the mower will RPM
search.

Tuts suggestions/comments.

1. Clean the filter sponge and let us know if the problem exists.
2. Does your mower have an adjustable throttle control on the handle?

The answer may not be here--but a great starting place--short of carb
teardown or flywheel removal--wouldn't you agree?

Tut

"Asimov" writes:

"cnctut" bravely wrote to "All" (11 May 05 10:52:14)
--- on the heady topic of " Lawnmower idle question"

From the small motor faq:

" Air vane governor. The air flow provided by the
flywheel/blower passes by a plate which is coupled to the
carburetor throttle plate acting against a spring force.

Flyweight governor. A spinning gear assembly with a pair of
weights is driven by the camshaft. As the centrifugal force
of the weights increases, they move a sleeve which presses
against a lever whose shaft passes through the crankcase.
This lever then operates the carburetor throttle plate
against a spring force.
With both types, increasing the spring force will increase the
engine speed.
"

Hunting is often caused by a defect in the governor system. Check the
blade (plastic?) of the governor paddle is free to move and that the
cam to which it connects has the proper spring tension. As the motor
speeds up the flywheel impellor blows air against the blade and cuts
the trottle down. When the motor slows down the blade drops back and
the spring returns the throttle higher.

One note though: He has an idle speed problem where the governor is
likely not involved unless it is way misadjuated.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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spongehead--

A carb swap may solve your problem if off a similair 3.5 engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

Good Luck

Tut

"cnctut" writes:

spongehead--

A carb swap may solve your problem if off a similair 3.5 engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

What fun is that? ;-)

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
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Sam Goldwasser wrote:
"cnctut" writes:

spongehead--

A carb swap may solve your problem if off a similair 3.5
engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might
help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at
solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

What fun is that? ;-)

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents:
http://repairfaq.ece.drexel.edu/REPAIR/
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above is
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can
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Sam

There are practical limits to fun--the grass keeps growing and the wife
doesn't like it long. Remember that microwave I was trying to
fix--"Sharp powers down after 40 seconds"--couldn't get parts so bought
a new one. The wife is very happy now--should have bought a new one
earlier--good note is that my parts box is now full of used microwave
items--maybe I can use some of them before I die--probably not
though.;-))

Tut

On 11 May 2005 10:40:01 -0700, "spongehead"
wrote:

I have an old Briggs and Stratton 3.5hp push behind lawnmower and the
idle revvs up and down constantly. Never idles normal. The spring on
the shaft idle looks good. Any help on what this might be would be
greatly appreciated.

It's the carbuerator diaphram, worn out most likely.
Yours is the plastic bodied carburator with the black or red primer
bulb yes?
If so you'll need to purchase a new diaphram and gasket for the carb,
about 4 bucks or so at a lawnmower parts shop.
The carb is secured with 5 philllips head screws. Take those out and
gently pry the plastic carb off the fuel tank.
Take care not to lose the diaphram spring( it'll be on the bottom side
of the carb.) or the mesh filter screen on the main fuel intake port.
Note whether the fiber gasket is on the carb side or the tank side(
varies with each model.) of the rubber diaphram.
Replace new ones in that order. Take care not to crease or wrinkle the
rubber diaphram whille tightening the screws down and you should be
good as new.
While apart use a good aerosol carb spray to clean out the carb and
tank resevoirs.(just about any brand but Gumout will do, I use Super
Tech brand found at Wal-mart. Autozone brand of carb spray is good as
well.)
Spray through the intake port(under mesh screen) to back flush the
supply pipe and the main port in the carb throat as well.
blow off any excess cleaner or allow to dry before replacing rubber
diaphram.(cleaner will attack the rubber shortening it's life.)
Any questions in particular just post back.
One of my many skills is small engine mechanic and I have years of
experience with lawnmowers.

But dont forget to check and clean/replace the fuel filter while you are
doing the job

David

spongehead wrote:

Thanks for all the replies, I will be taking the carb off for a good
cleaning and replace the air filter. I'll let you know how it goes.
Thanks again!!

"cnctut" writes:

Sam Goldwasser wrote:
"cnctut" writes:

spongehead--

A carb swap may solve your problem if off a similair 3.5
engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might
help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at
solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

What fun is that? ;-)

--- sam | Sci.Electronics.Repair FAQ Mirror:

There are practical limits to fun--the grass keeps growing and the wife
doesn't like it long. Remember that microwave I was trying to
fix--"Sharp powers down after 40 seconds"--couldn't get parts so bought
a new one. The wife is very happy now--should have bought a new one
earlier--good note is that my parts box is now full of used microwave
items--maybe I can use some of them before I die--probably not
though.;-))

Oh, I definitely agree when it comes to strange problems like the one
you had. But unstable idle on a lawnmower engine isn't rocket science
or something that's likely to stump everyone.

And there's my "fix once rule": I don't mind repairing something I picked
up on eBay cheap (replaces garage sales!) or what I might have bought new
many years ago. But I don't want to have to deal with it more than once!

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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spongehead--

When you get it fixed--would appreciate an update on what was the
problem.

Thanks

Tut

spongehead--

One last thought--check the plug for soot (running rich)--clogged air
filter causes lower Air/Fuel ratios--leads to poor burn, soot and
suttle misfires--leading to rpm searching.

Good Luck

Tut

"Sam Goldwasser" wrote in message
...
"cnctut" writes:

spongehead--

A carb swap may solve your problem if off a similair 3.5 engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

What fun is that? ;-)


Not to mention the new ones are such crap, I mean come on, plastic carbs??
The old stuff was made so much better.

"kip" wrote in message
.. .
Yes But its just easier to put a New one in
cause the chances of him ruining the valve is pretty good.
We are not talking big coin here ..
Just done my Lawnboy ..
cheers
kip


And the chances are just as great of ruining the new one, just don't crank
it down tight.

I took the carb off and found that rubber O-ring was broken. I assume
that was the culpret. I hosed down the carb with wd-40 and she started
up with no idle problem. However now the idle is too low. I probably
stretched the spring or something but atleast it mows the lawn! Thanks
for all the help!

"James Sweet" wrote in message
news:nkDhe.6615$Y12.4627@trnddc09...

"Sam Goldwasser" wrote in message
...
"cnctut" writes:

spongehead--

A carb swap may solve your problem if off a similair 3.5 engine--too
much work though. You mentioned your throttle adjustment was
frozen--you might try advancing the control wire (pliers might help)
toward a faster run postion to get away from slow idle.

If this doesn't work--carb cleaner would be my next attempt at solving
the problem. Squirt it every where (in and around the carb.)

Lastly, as your time and parts cost creep higher and higher--don't
forget a new 3.5HP mower is only $99. ;-))

What fun is that? ;-)


Not to mention the new ones are such crap, I mean come on, plastic carbs??
The old stuff was made so much better.


No doubt....

On a different subject; the last time I had occasion to check the Repair FAQ
regarding a lawnmower issue, (I had a shear key problem which was easily
fixed with the info contained there. Thanks, Sam) I noticed a very
interesting dialogue concerning the relative merits of Briggs and Tecumseh
small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I thought
I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and maintenance, but
they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start much
easier, although that's probably due to the priming bulb which my Briggs
does not have. They start using oil right out of the box, however. I have
to check and add oil on almost every use. My Eager1 uses almost twice as
much fuel to mow the same yard as my older Briggs of the same horsepower and
cut width. I almost never have to add oil to the Briggs in an entire
season.

Given the greater oil and gas consumption, I assume that the Tecumsehs are
emitting considerably more pollutants per hour of use. The consumables only
add a negligible amount to my lawn-care costs every year; but multiplied by
(however many millions) of them out there.....

Any thoughts?

jak

No doubt....

On a different subject; the last time I had occasion to check the Repair
FAQ
regarding a lawnmower issue, (I had a shear key problem which was easily
fixed with the info contained there. Thanks, Sam) I noticed a very
interesting dialogue concerning the relative merits of Briggs and Tecumseh
small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I
thought
I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and maintenance,
but
they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start much
easier, although that's probably due to the priming bulb which my Briggs
does not have. They start using oil right out of the box, however. I
have
to check and add oil on almost every use. My Eager1 uses almost twice as
much fuel to mow the same yard as my older Briggs of the same horsepower
and
cut width. I almost never have to add oil to the Briggs in an entire
season.

Given the greater oil and gas consumption, I assume that the Tecumsehs are
emitting considerably more pollutants per hour of use. The consumables
only
add a negligible amount to my lawn-care costs every year; but multiplied
by
(however many millions) of them out there.....

Any thoughts?

jak


Well it's hard to say these days, back when I was tinkering with this stuff
a lot I was dealing with engines made mostly in the 1970's and the Briggs
motors were very noticeably better made and easier to work on. The
Tecumsehs' were nothing but a pain in the ass, carb problems, ignition
problems, a few common models would regularly throw rods. It was no shock
since they were always about 40% cheaper than a comparable B&S. Now days I
don't really know, the Tecumseh engines seem to have improved somewhat,
while the Briggs engines have gotten *very* noticeably poorer. Somebody said
they're now made in Asia so perhaps that's when the quality took a dive. BTW
the new ones do have a primer bulb, haven't tried starting one though. My
mom has an old mower with a Tecumseh and it does actually start quite easily
though I have to take apart the carb and clean out the banjo bolt on the
float bowl every year, never had to do that with an old Briggs. Unfortunatly
I never compared fuel consumption but I don't recall oil usage problems on
either.

On Tue, 17 May 2005 03:18:06 GMT, "James Sweet"
wrote:



No doubt....

On a different subject; the last time I had occasion to check the Repair
FAQ
regarding a lawnmower issue, (I had a shear key problem which was easily
fixed with the info contained there. Thanks, Sam) I noticed a very
interesting dialogue concerning the relative merits of Briggs and Tecumseh
small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I
thought
I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and maintenance,
but
they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start much
easier, although that's probably due to the priming bulb which my Briggs
does not have. They start using oil right out of the box, however. I
have
to check and add oil on almost every use. My Eager1 uses almost twice as
much fuel to mow the same yard as my older Briggs of the same horsepower
and
cut width. I almost never have to add oil to the Briggs in an entire
season.

Given the greater oil and gas consumption, I assume that the Tecumsehs are
emitting considerably more pollutants per hour of use. The consumables
only
add a negligible amount to my lawn-care costs every year; but multiplied
by
(however many millions) of them out there.....

Any thoughts?

jak


Well it's hard to say these days, back when I was tinkering with this stuff
a lot I was dealing with engines made mostly in the 1970's and the Briggs
motors were very noticeably better made and easier to work on. The
Tecumsehs' were nothing but a pain in the ass, carb problems, ignition
problems, a few common models would regularly throw rods. It was no shock
since they were always about 40% cheaper than a comparable B&S. Now days I
don't really know, the Tecumseh engines seem to have improved somewhat,
while the Briggs engines have gotten *very* noticeably poorer. Somebody said
they're now made in Asia so perhaps that's when the quality took a dive. BTW
the new ones do have a primer bulb, haven't tried starting one though. My
mom has an old mower with a Tecumseh and it does actually start quite easily
though I have to take apart the carb and clean out the banjo bolt on the
float bowl every year, never had to do that with an old Briggs. Unfortunatly
I never compared fuel consumption but I don't recall oil usage problems on
either.


Yes, there was a time when Briggs were better engines.
Not so anymore. B&S has gotten into the parts game. They make nearly
as much profit on parts and service as they do intial sale.
Techumseh had to rethink their whole market strategy in the late 70's
and refocused on building better quality engines that were certainly
more standardized. On virtually every Techumseh vertical shaft engine
the carbs and coils are interchangeable, unlike Briggs where every
engine requires a particular model coil or carbuerator-setup.

Odd that your eager-1(Sears) mower uses so much oil. I'd say it might
be just the particular engine as virtually none of the ones I've used
or serviced ever developed this problem during their useful life.(Cast
iron sleeves and 2 oil rings unlike the single ring in Briggs and the
cheap alloys used in both the sleeve and ring.)
The poorer, cheap design in the Briggs carbs make for a much worse
problem in regards to polution as they tend to run rich with just a
little age.(I've seen some come into my shop that are runnign so rich
that they actually wash the cylinder. This results in excessive wear
on the sleeve and rings, allowing bypass into the crankcase. Once the
oil is broken down by the gas it'll bypass the rings and the result is
a smoking engine.(great if you want to fog your yard as you cut it.)
Techuseh carbs are actually easy to operate and care for once you
learn some basics.
They're float style carbs and as such you can't just run 'em and
forget 'em. leaving gas in the carb and tank off season is the worst
thing you can do. (Most people don't realize that gasoline actually
goes bad with time and actually expect a mower that's sat unused for
six months to just crank up on the first pull.)
Run the tank dry at the last cutting of the season then loosen the
Bowl nut and drain the gas out of the float bowl.(It's easy, all it
takes is a 1/2 inch socket to loosen it.)
Then leave it dry for the winter, DON'T put any type of winterizer in
it. Worst stuff in the world. Just ensures you'll be taking it in for
a carb job as the stuff just turns to jelly and will make a real mess
of your carb and tank.
There's just no way to "preserve" gas, use it or lose it.

If you want proof as to Techumseh's quality over Briggs just look at
how Briggs has copied Techumseh design.
Techumseh has the best design in a starter recoil mechanism hands
down, Briggs finally gave up using their ball bearing starter clutch
mechanism on all their 5hp or larger engines and copied the Techumseh
design out right.(stilll not as good.)
They went to a float style carb but picked what is in my opinion one
of the worst makes, Walbro.
I tell all my customers if they insist on a Briggs just get one of the
Sprints, either a 3.5 or 4hp model and don't expect much more than 2
years of use out of it. I have some customers still using the same
Craftsmans mower with a Techumseh engine for 10 years or longer.
I gave my inlaws one of my personal Craftsmans that I purchased back
in 82 and it's still going strong, with NO major engine work at all.

On 15 May 2005 06:09:24 -0700, "spongehead"
wrote:

I took the carb off and found that rubber O-ring was broken. I assume
that was the culpret. I hosed down the carb with wd-40 and she started
up with no idle problem. However now the idle is too low. I probably
stretched the spring or something but atleast it mows the lawn! Thanks
for all the help!

You can get a new o-ring at you local harware store for about 50
cents.
It's usually size 42 on the chart in the o-ring boxes.
I can look it up for you if you can't get a match.

I have added the major parts of this thread to the LM FAQ.

Thanks.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

none writes:

On Tue, 17 May 2005 03:18:06 GMT, "James Sweet"
wrote:



No doubt....

On a different subject; the last time I had occasion to check the Repair
FAQ
regarding a lawnmower issue, (I had a shear key problem which was easily
fixed with the info contained there. Thanks, Sam) I noticed a very
interesting dialogue concerning the relative merits of Briggs and Tecumseh
small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I
thought
I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and maintenance,
but
they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start much
easier, although that's probably due to the priming bulb which my Briggs
does not have. They start using oil right out of the box, however. I
have
to check and add oil on almost every use. My Eager1 uses almost twice as
much fuel to mow the same yard as my older Briggs of the same horsepower
and
cut width. I almost never have to add oil to the Briggs in an entire
season.

Given the greater oil and gas consumption, I assume that the Tecumsehs are
emitting considerably more pollutants per hour of use. The consumables
only
add a negligible amount to my lawn-care costs every year; but multiplied
by
(however many millions) of them out there.....

Any thoughts?

jak


Well it's hard to say these days, back when I was tinkering with this stuff
a lot I was dealing with engines made mostly in the 1970's and the Briggs
motors were very noticeably better made and easier to work on. The
Tecumsehs' were nothing but a pain in the ass, carb problems, ignition
problems, a few common models would regularly throw rods. It was no shock
since they were always about 40% cheaper than a comparable B&S. Now days I
don't really know, the Tecumseh engines seem to have improved somewhat,
while the Briggs engines have gotten *very* noticeably poorer. Somebody said
they're now made in Asia so perhaps that's when the quality took a dive. BTW
the new ones do have a primer bulb, haven't tried starting one though. My
mom has an old mower with a Tecumseh and it does actually start quite easily
though I have to take apart the carb and clean out the banjo bolt on the
float bowl every year, never had to do that with an old Briggs. Unfortunatly
I never compared fuel consumption but I don't recall oil usage problems on
either.


Yes, there was a time when Briggs were better engines.
Not so anymore. B&S has gotten into the parts game. They make nearly
as much profit on parts and service as they do intial sale.
Techumseh had to rethink their whole market strategy in the late 70's
and refocused on building better quality engines that were certainly
more standardized. On virtually every Techumseh vertical shaft engine
the carbs and coils are interchangeable, unlike Briggs where every
engine requires a particular model coil or carbuerator-setup.

Odd that your eager-1(Sears) mower uses so much oil. I'd say it might
be just the particular engine as virtually none of the ones I've used
or serviced ever developed this problem during their useful life.(Cast
iron sleeves and 2 oil rings unlike the single ring in Briggs and the
cheap alloys used in both the sleeve and ring.)
The poorer, cheap design in the Briggs carbs make for a much worse
problem in regards to polution as they tend to run rich with just a
little age.(I've seen some come into my shop that are runnign so rich
that they actually wash the cylinder. This results in excessive wear
on the sleeve and rings, allowing bypass into the crankcase. Once the
oil is broken down by the gas it'll bypass the rings and the result is
a smoking engine.(great if you want to fog your yard as you cut it.)
Techuseh carbs are actually easy to operate and care for once you
learn some basics.
They're float style carbs and as such you can't just run 'em and
forget 'em. leaving gas in the carb and tank off season is the worst
thing you can do. (Most people don't realize that gasoline actually
goes bad with time and actually expect a mower that's sat unused for
six months to just crank up on the first pull.)
Run the tank dry at the last cutting of the season then loosen the
Bowl nut and drain the gas out of the float bowl.(It's easy, all it
takes is a 1/2 inch socket to loosen it.)
Then leave it dry for the winter, DON'T put any type of winterizer in
it. Worst stuff in the world. Just ensures you'll be taking it in for
a carb job as the stuff just turns to jelly and will make a real mess
of your carb and tank.
There's just no way to "preserve" gas, use it or lose it.

If you want proof as to Techumseh's quality over Briggs just look at
how Briggs has copied Techumseh design.
Techumseh has the best design in a starter recoil mechanism hands
down, Briggs finally gave up using their ball bearing starter clutch
mechanism on all their 5hp or larger engines and copied the Techumseh
design out right.(stilll not as good.)
They went to a float style carb but picked what is in my opinion one
of the worst makes, Walbro.
I tell all my customers if they insist on a Briggs just get one of the
Sprints, either a 3.5 or 4hp model and don't expect much more than 2
years of use out of it. I have some customers still using the same
Craftsmans mower with a Techumseh engine for 10 years or longer.
I gave my inlaws one of my personal Craftsmans that I purchased back
in 82 and it's still going strong, with NO major engine work at all.

James Sweet wrote:
No doubt....

On a different subject; the last time I had occasion to check the
Repair FAQ regarding a lawnmower issue, (I had a shear key problem
which was easily fixed with the info contained there. Thanks, Sam)
I noticed a very interesting dialogue concerning the relative merits
of Briggs and Tecumseh small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I
thought I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and
maintenance, but they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start
much easier, although that's probably due to the priming bulb which
my Briggs does not have. They start using oil right out of the box,
however. I have to check and add oil on almost every use. My
Eager1 uses almost twice as much fuel to mow the same yard as my
older Briggs of the same horsepower and cut width. I almost never
have to add oil to the Briggs in an entire season.

Given the greater oil and gas consumption, I assume that the
Tecumsehs are emitting considerably more pollutants per hour of use.
The consumables only add a negligible amount to my lawn-care costs
every year; but multiplied by (however many millions) of them out
there.....

Any thoughts?

jak


Well it's hard to say these days, back when I was tinkering with this
stuff a lot I was dealing with engines made mostly in the 1970's and
the Briggs motors were very noticeably better made and easier to work
on. The Tecumsehs' were nothing but a pain in the ass, carb problems,
ignition problems, a few common models would regularly throw rods. It
was no shock since they were always about 40% cheaper than a
comparable B&S. Now days I don't really know, the Tecumseh engines
seem to have improved somewhat, while the Briggs engines have gotten
*very* noticeably poorer. Somebody said they're now made in Asia so
perhaps that's when the quality took a dive. BTW the new ones do have
a primer bulb, haven't tried starting one though. My mom has an old
mower with a Tecumseh and it does actually start quite easily though
I have to take apart the carb and clean out the banjo bolt on the
float bowl every year, never had to do that with an old Briggs.
Unfortunatly I never compared fuel consumption but I don't recall oil
usage problems on either.

I've not had to pull the carb on either of my Tec's, but the Briggs (bought
new in the early 90's) is laid up until I can pull the carb and determine if
it's the cause of the hard starting. Both Tec's have worked reliably since
I aquired them, except for the shear pin, which was result of operator
error, of course. This morning I pulled out one of them and oil was below
the dipstick. (5.5 hp, self propelled pusher...I ran two+ tanks of gas
through it last session, and oil was full when I started...need to check
more often!)

However, both of them were aquired used, as opposed to the Briggs. I wonder
if they were abused in an earlier life. I had one other many years ago, and
it 'used' oil/gas as well. It might have been old enough to have been made
in the 70's...thrift store find.

I'm glad to hear Tecumseh quality is going up. Except for needing to keep a
close watch on the oil, and seemingly needing to fill gas more often, both
of these mowers have been relatively flawless.

It's also a shame about Briggs & Stratton. The first engine I ever worked
on was a horizontal shaft Briggs which came off my dads old reel-type power
mower from the 50's. I pulled it off the mower some time in the mid-60's,
used a pipe wrench to break the rings free and mounted it on a go-cart. It
was too small for the application at a (maybe two, it's been a long time)
horse and a half, but it ran well.

jak

Sam Goldwasser wrote:
I have added the major parts of this thread to the LM FAQ.

So it wasn't too late. Thanks again, Sam.

jak
Thanks.

"jakdedert" writes:

Sam Goldwasser wrote:
I have added the major parts of this thread to the LM FAQ.

So it wasn't too late. Thanks again, Sam.

Never too late.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

On Wed, 18 May 2005 11:43:48 -0500, "jakdedert"
wrote:

James Sweet wrote:
No doubt....

On a different subject; the last time I had occasion to check the
Repair FAQ regarding a lawnmower issue, (I had a shear key problem
which was easily fixed with the info contained there. Thanks, Sam)
I noticed a very interesting dialogue concerning the relative merits
of Briggs and Tecumseh small engines.

Being how it's much too late (probably) to get my $.02 in the FAQ, I
thought I'd post my opinion he

IME, Briggs motors are much more 'finicky' for starting and
maintenance, but they last longer and use much less gas and oil.

The Tecumsehs (I have two of those, and one Briggs & Stratton) start
much easier, although that's probably due to the priming bulb which
my Briggs does not have. They start using oil right out of the box,
however. I have to check and add oil on almost every use. My
Eager1 uses almost twice as much fuel to mow the same yard as my
older Briggs of the same horsepower and cut width. I almost never
have to add oil to the Briggs in an entire season.

Given the greater oil and gas consumption, I assume that the
Tecumsehs are emitting considerably more pollutants per hour of use.
The consumables only add a negligible amount to my lawn-care costs
every year; but multiplied by (however many millions) of them out
there.....

Any thoughts?

jak


Well it's hard to say these days, back when I was tinkering with this
stuff a lot I was dealing with engines made mostly in the 1970's and
the Briggs motors were very noticeably better made and easier to work
on. The Tecumsehs' were nothing but a pain in the ass, carb problems,
ignition problems, a few common models would regularly throw rods. It
was no shock since they were always about 40% cheaper than a
comparable B&S. Now days I don't really know, the Tecumseh engines
seem to have improved somewhat, while the Briggs engines have gotten
*very* noticeably poorer. Somebody said they're now made in Asia so
perhaps that's when the quality took a dive. BTW the new ones do have
a primer bulb, haven't tried starting one though. My mom has an old
mower with a Tecumseh and it does actually start quite easily though
I have to take apart the carb and clean out the banjo bolt on the
float bowl every year, never had to do that with an old Briggs.
Unfortunatly I never compared fuel consumption but I don't recall oil
usage problems on either.

I've not had to pull the carb on either of my Tec's, but the Briggs (bought
new in the early 90's) is laid up until I can pull the carb and determine if
it's the cause of the hard starting. Both Tec's have worked reliably since
I aquired them, except for the shear pin, which was result of operator
error, of course. This morning I pulled out one of them and oil was below
the dipstick. (5.5 hp, self propelled pusher...I ran two+ tanks of gas
through it last session, and oil was full when I started...need to check
more often!)

However, both of them were aquired used, as opposed to the Briggs. I wonder
if they were abused in an earlier life. I had one other many years ago, and
it 'used' oil/gas as well. It might have been old enough to have been made
in the 70's...thrift store find.

I'm glad to hear Tecumseh quality is going up. Except for needing to keep a
close watch on the oil, and seemingly needing to fill gas more often, both
of these mowers have been relatively flawless.

It's also a shame about Briggs & Stratton. The first engine I ever worked
on was a horizontal shaft Briggs which came off my dads old reel-type power
mower from the 50's. I pulled it off the mower some time in the mid-60's,
used a pipe wrench to break the rings free and mounted it on a go-cart. It
was too small for the application at a (maybe two, it's been a long time)
horse and a half, but it ran well.

jak

Yes the earlier Techumsehs did have a problem regards to burning oil.
They were built terribly cheap way back.
And yep, the earlier B&S engines were built like a tank.
The problem with using the older Briggs horizontal shaft motors for
go-carts or minibikes was they had low rpms and not much torque.
The ones they marketed specifically for that purpose were setup tp
spin a bit faster and had higher compression.
You could fudge a bit with some of the 3hp models by resetting the
mean idle on the govenor springs and either rejetting the carb for
quicker response or replacing it with a bigger throated one so the
engine could breath a bit better.
Using a low hp engine like a 2 or a 2 and a half you'd have had to
change out the drive sprocket for a much larger one to make it an easy
pull. Which of course would have made it as slow as a turtle.