Howdy All;

I have a lawboy mower that was built in the early '90's that I am
having a lot of trouble getting it to run. I can find the model and
serial number if it is relevant but I don't have it handy: it says "4hp
Commercial" on the tank cover and no PTO for self-propell. It has been
very picky about gas since I bought it used two years ago; it won't run
if I leave gas in the tank so I drain what is left over back into the
can.

The first day I used it this year it fired up with just two pulls and
the throttle at full choke. Ever since then though when I've tried to
start it the best I would get is a quick and easy start like the first
time but it dies and refuses to restart after about 90 seconds of
runtime. If I try to restart it sometimes I will get one or two
strokes to light off will not run.

I removed the carb and cleaned it out and also cleaned out the tank,
both with carb cleaner. I also pulled and replaced the old plug, which
was fouled pretty bad after just one season. Neither of those things
has made any difference. I am using 87 octane gas straight from the
pump mixed 32:1 with real Lawnboy oil as per the markings on the mower.

I'm handy and could follow directions, but I've run out of things to
look for. Does anyone out there have a suggestion for what may be
wrong with me or my engine? I'd like to keep it running if possible as
I can't afford a new mower that could hold a candle to this old beast,
when it is running at least .

Thanks,
Matthew

wrote:
Howdy All;

I have a lawboy mower that was built in the early '90's that I am
having a lot of trouble getting it to run. I can find the model and
serial number if it is relevant but I don't have it handy: it says "4hp
Commercial" on the tank cover and no PTO for self-propell. It has been
very picky about gas since I bought it used two years ago; it won't run
if I leave gas in the tank so I drain what is left over back into the
can.

The first day I used it this year it fired up with just two pulls and
the throttle at full choke. Ever since then though when I've tried to
start it the best I would get is a quick and easy start like the first
time but it dies and refuses to restart after about 90 seconds of
runtime. If I try to restart it sometimes I will get one or two
strokes to light off will not run.

I removed the carb and cleaned it out and also cleaned out the tank,
both with carb cleaner. I also pulled and replaced the old plug, which
was fouled pretty bad after just one season. Neither of those things
has made any difference. I am using 87 octane gas straight from the
pump mixed 32:1 with real Lawnboy oil as per the markings on the mower.

I'm handy and could follow directions, but I've run out of things to
look for. Does anyone out there have a suggestion for what may be
wrong with me or my engine? I'd like to keep it running if possible as
I can't afford a new mower that could hold a candle to this old beast,
when it is running at least .

Thanks,
Matthew

Could it be in your area they've recently switched to 10% ethanol, and
your jetting is now 14% off?

Dave

On 15 May 2006 09:44:53 -0700, wrote:

Howdy All;

I have a lawboy mower that was built in the early '90's that I am
having a lot of trouble getting it to run. I can find the model and
serial number if it is relevant but I don't have it handy: it says "4hp
Commercial" on the tank cover and no PTO for self-propell. It has been
very picky about gas since I bought it used two years ago; it won't run
if I leave gas in the tank so I drain what is left over back into the
can.

The first day I used it this year it fired up with just two pulls and
the throttle at full choke. Ever since then though when I've tried to
start it the best I would get is a quick and easy start like the first
time but it dies and refuses to restart after about 90 seconds of
runtime. If I try to restart it sometimes I will get one or two
strokes to light off will not run.

I removed the carb and cleaned it out and also cleaned out the tank,
both with carb cleaner. I also pulled and replaced the old plug, which
was fouled pretty bad after just one season. Neither of those things
has made any difference. I am using 87 octane gas straight from the
pump mixed 32:1 with real Lawnboy oil as per the markings on the mower.

I'm handy and could follow directions, but I've run out of things to
look for. Does anyone out there have a suggestion for what may be
wrong with me or my engine? I'd like to keep it running if possible as
I can't afford a new mower that could hold a candle to this old beast,
when it is running at least .

Thanks,
Matthew


Gas tank screen/fuel line dirty????


Oren

"My doctor says I have a malformed public-duty gland
and a natural deficiency in moral fiber, and that I am therefore
excused from saving Universes."

Greetings Matthew...

Ok you have done some good stuff there.

You cleaned out the gas tank, good start.

Did you make sure that the gas was flowing
when it was reconnected to the carb??

Ok moving over to the carb, its a pretty simple
setup with a float. I presume you look the
bowl off and cleaned that out right?
Depending on the unit, some carbs have
a screw on the bottom that also has two little
holes going through it. In the center of
that screw SHOULD be a hole that can
EASILY get gummed up with 2 cycle gas.
Make sure that's clean. Did you make sure
that the float in the carb is clean and free moving?

Now one thing you can easily see is the primer.
Some machine dont have one others do.
If you have a primer, when you prime it look
into the carb. The jet is right in the middle
behind the choke butterfly. When you prime
you SHOULD see a squirt of gas shoot up out
of the carb. If not, enough gas isnt getting into
the bowl for a few reasons.

Dont dismiss a bad fuel line either, small cracks
in it can cause all sort of funny behavior.

Tom

a screw on the bottom that also has two little holes

I'll check that. I know what you are talking about, but I didn't
realize it was anything more special than a small bolt so I will make
sure it is clean.

I'm pretty sure the float and its valve are working because the bowl
fills as it should but doesn't leak from the jet even when I blow into
the gas tank (I know, I know). This one is too new to have the primer
bulb; it has a separate butterfly for the choke instead. I know gas
gets as far as the bowl, but can't guarantee that it gets any farther.

Matthew

I have a lawboy mower that was built in the early '90's that I am having a lot of trouble getting it to run.

I think I've narrowed it down to the ignition side. I pulled the plug,
closed the safety switch and touched the plug threads to the cooling
fins: no spark. I removed the ignition module and cleaned up the
contact areas with a sanding pad and reinstalled it. I gave the
engine another spin and got one spark. After that I couldn't get
anything else.

This is the second lawnboy I've had that died this way: the ignition
module works when it feels like it, which is rarely. Is this something
that is common with these engines? Is there something I could be doing
wrong that these things die out from under me after just a couple of
seasons in my hands? The plug is brand new and all the contact points
are shiny and clean on both the engine block and the module itself. I
also made sure to gap the plug and the module/flywheel to spec.

Matthew

Didn't realise they still made 2-stroke mowers even in the 90s. Do
they still? Remember them from when I was a kid. I have a 2-stroke
snowblower that I idiotically bought used off a guy moving to Florida-
works fine, though I can hardly be bothered with it- mixing, etc.
2-stroke makes sense for portable devices, but a mower? That said, I
understand your frugality- good luck.

wrote:
10% ethanol

I don't know what the schedule or regulations are for the blends but I
am near Chicago so it is a definite possiblity. How would I compensate
for that? The gas that ran great was left over from late last year so
it might have been winter blend. I played a little with the adjustment
on the carb but it didn't seem to make an difference. It could have
already been flooded though.

Can this old beast be tuned to run on E10 or E15?

Air cleaner clogged?

I tried it without the filter or cover just to see if it would
start/run on the sidewalk and that didn't make any difference.

Matthew

If the carb is sophisticated enough to have jets, you'd get a larger
main jet and pilot jet.

If it doesn't have replaceable jets, adding a little intake restriction
might turn the trick.

Dave

2-stroke makes sense for portable devices, but a mower?

alright, I'll take the bait:

4-stroke makes sense for a car, but a mower?

Seriously, 2-stroke is great for a mower. The power to weight ratio is
better than a 4-stroke and the simplicity of operation makes for a
durable, light, cheap machine.

Ok, I'll take it, too. Maybe I should get a 2 stroke mower- my yard
has steep slopes. Used to drive a Saab way back when, but it was a
V-4 Ford tractor engine(I had to switch it out once)- just missed by a
couple years the 3 cylinder 2 stroke variety. BTW I've always
considered the Wankel (such as Mazda used) a sort of 2 stroke- for
better and worse- great power to weight ratio, poor separation between
the strokes, thus emissions/ mileage limitations, burned valves, etc.

According to :

I think I've narrowed it down to the ignition side. I pulled the plug,
closed the safety switch and touched the plug threads to the cooling
fins: no spark. I removed the ignition module and cleaned up the
contact areas with a sanding pad and reinstalled it. I gave the
engine another spin and got one spark. After that I couldn't get
anything else.

Our lawnboy has had its ignition condenser die twice. That might be it.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to :
2-stroke makes sense for portable devices, but a mower?

alright, I'll take the bait:

4-stroke makes sense for a car, but a mower?

Seriously, 2-stroke is great for a mower. The power to weight ratio is
better than a 4-stroke and the simplicity of operation makes for a
durable, light, cheap machine.

All of the oil you put in the gas ends up in the air, incompletely burned.

Yes, 4-stroke is more expensive and heavier. However, good ones tend
to last a lot longer than 2-stroke (many of which can basically be
considered disposable engines), usually quieter, usually easier to start,
and they're certainly a lot cleaner in operation.

Each has their place.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Our lawnboy has had its ignition condense die twice. That might be it.

Yup, got a new one from zacm.com (crappy web design, but good people)
and the thing fired right up. I did have a tough time finding a
replacement plug for it, though. I found a Lawn-Boy branded one at Ace
for about $7 - no thanks. I did eventually find it at Lowes for about
$2.50. I also picked up a new air filter and reed valves, but seeing
what would be required to actually replace the reeds I think I'll wait
on those even though they are a little leaky.

I am happy to be mowing again.

Matthew Price

It would be helpful if you knew what you were talking about. My 1986
(that's right - 20 years old) Lawnboy starts strong and runs stronger
that any push mower engine i've ever had. And believe me, I've had a
lot of them, Briggs and Techmseh. You claim that 4 strokes are "usually
quieter", "usually easier to start". Wrong on both counts. My LB starts
on the second pull EVERY time and is the quietest mower I've had.
The great thing about the Lawnboy is that there are needle bearings at
the bottom end constantly bathed in clean oil. I'm seriously expecting
another 20 years out of this mower.

Chris;
You have to use a good lawnboy to understand.

I personally have a lawnboy commercial unit, it works freaking
great. It will basically cut and suck up anything on the lawn.
I received a Honda unit from my parents. The engine on it
is real nice but it just doesnt have the vacuum power to take
the excess clips off the lawn. Its a problem with ALL
4 cycle engines/mowers. You need to have some recent
suction and a 2 cycle by design spins up higher than
4 cycle lawn mower motors.

According to Lhead :
It would be helpful if you knew what you were talking about. My 1986
(that's right - 20 years old) Lawnboy starts strong and runs stronger
that any push mower engine i've ever had.

My lawnboy is 3 years older than yours. So there! ;-)

It starts second pull every time, as long as I remember to tilt
the thing when I prime it, and the condensor hasn't gone bad, and
it hasn't been idle too many years.

Then again, the 1973 6HP Tecumseh 4 stroke wood chipper starts
first pull (except when the carb got gummed up after sitting
idle in the rain and snow for about 5 years).

And the 1970 12HP 4 stroke Kohler has always started quickly - even
with a blown head gasket. Except in the winter. Try starting
that LB at -30C sometime.

The kohler is considerably quieter than the LB except when it backfires.

And believe me, I've had a
lot of them, Briggs and Techmseh. You claim that 4 strokes are "usually
quieter", "usually easier to start". Wrong on both counts. My LB starts
on the second pull EVERY time and is the quietest mower I've had.
The great thing about the Lawnboy is that there are needle bearings at
the bottom end constantly bathed in clean oil. I'm seriously expecting
another 20 years out of this mower.

How can it get bathed in oil? It's a two stroke. It don't have no
oil bath.

I said _usually_. A decent 4 stroke Honda or the like with compression
reduction during start will start easier than virtually any 2 stroke.
And will be quieter given remotely comparable mufflers.

Certainly, 2 stroke has a considerable power-to-weight advantage over
4 stroke. At the expense of (usually) higher RPMS, more noise,
sometimes more difficult starting, and a smoke cloud of partially
burned oil.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to :
Chris;
You have to use a good lawnboy to understand.

I have a good lawnboy. I understand.

I personally have a lawnboy commercial unit, it works freaking
great. It will basically cut and suck up anything on the lawn.
I received a Honda unit from my parents. The engine on it
is real nice but it just doesnt have the vacuum power to take
the excess clips off the lawn. Its a problem with ALL
4 cycle engines/mowers.

No, it's an issue with the blade you put on it.

You need to have some recent
suction and a 2 cycle by design spins up higher than
4 cycle lawn mower motors.

Not a great deal more than 4 stroke given the application.
You don't want the blade going much faster than 3600RPM 2 or
4 stroke. Even if it did, you just change the pitch on the
blade to get more suction if that's what you want.

Your commercial unit is designed for suction bagging.

My lawnboy's suction ain't all that great - but it's not
a commercial bagger. I don't bag, so it don't matter.

[Mind you, we're building a wind tunnel with a 2 stroke
weed wacker motor. A 16x16 prop generates quite a wind blast
at 8000-9000 RPM. During tests just below freezing, we
calculated a windchill factor of -50C. at 100% efficiency on
the prop, that's better than a 100MPH wind blast.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:
According to Lhead :
It would be helpful if you knew what you were talking about. My 1986
(that's right - 20 years old) Lawnboy starts strong and runs stronger
that any push mower engine i've ever had.

My lawnboy is 3 years older than yours. So there! ;-)

It starts second pull every time, as long as I remember to tilt
the thing when I prime it, and the condensor hasn't gone bad, and
it hasn't been idle too many years.

Then again, the 1973 6HP Tecumseh 4 stroke wood chipper starts
first pull (except when the carb got gummed up after sitting
idle in the rain and snow for about 5 years).

And the 1970 12HP 4 stroke Kohler has always started quickly - even
with a blown head gasket. Except in the winter. Try starting
that LB at -30C sometime.

The kohler is considerably quieter than the LB except when it backfires.

And believe me, I've had a
lot of them, Briggs and Techmseh. You claim that 4 strokes are "usually
quieter", "usually easier to start". Wrong on both counts. My LB starts
on the second pull EVERY time and is the quietest mower I've had.
The great thing about the Lawnboy is that there are needle bearings at
the bottom end constantly bathed in clean oil. I'm seriously expecting
another 20 years out of this mower.

How can it get bathed in oil? It's a two stroke. It don't have no
oil bath.

Again, it would be helpful if you knew what you were talking about.
No, it 'don't have no oil bath' , whatever that is. But remember that
stuff you mix with the gas in a 32:1 ratio? Right! The oil!. Well,
guess what Chris, that same oil, because of the design of the 2 stroke
engine is pulled into and through the crankcase before it's burnt in
the cylinder. The oil bathes the bottom end constantly. And, with each
stroke a new charge of the mixture is brought in through the
carburetor. Ain't education wonderful?

I said _usually_. A decent 4 stroke Honda or the like with compression
reduction during start will start easier than virtually any 2 stroke.
And will be quieter given remotely comparable mufflers.

Certainly, 2 stroke has a considerable power-to-weight advantage over
4 stroke. At the expense of (usually) higher RPMS, more noise,
sometimes more difficult starting, and a smoke cloud of partially
burned oil.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to Lhead :

Chris Lewis wrote:
How can it get bathed in oil? It's a two stroke. It don't have no
oil bath.

Again, it would be helpful if you knew what you were talking about.
No, it 'don't have no oil bath' , whatever that is. But remember that
stuff you mix with the gas in a 32:1 ratio? Right! The oil!. Well,
guess what Chris, that same oil, because of the design of the 2 stroke
engine is pulled into and through the crankcase before it's burnt in
the cylinder. The oil bathes the bottom end constantly. And, with each
stroke a new charge of the mixture is brought in through the
carburetor. Ain't education wonderful?

Sigh.

You know, I don't expect everyone to have taken not one, but two
small engine repair courses as I have and intimately know the details of
how four stroke and the three types of 2 stroke engines work, but
at _least_ you should know the difference between having a _bath_
and having a _shower_.

The oil-gas mix in a two stroke is atomized in the carbureter,
and pulled thru the crankcase and thence to the intake port.
Thus, the insides of the motor are showered with a gas oil
mix, and the oil is then run thru the cylinder head and
(partially!) burned before being dumped into the atmosphere.

As for example, the pilots of certain aircraft in world war
one were continuously sprayed in the face with a partially
burned laxative (they used castor oil in those days).

Meanwhile, in a four stroke, the crank and cylinder head is
mostly isolated. The oil is in a _bath_ at the bottom of the
crankcase, and the crank, and bottom end of the piston rod
splash (and to a certain extent are bathed _in_) the oil at
the bottom of the crank. The oil _stays_ in the engine
and doesn't spray anyone in the face.

So, no, a 2 stroke doesn't bathe its parts in oil. But a 4
stroke does.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.