Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

On Mon, 22 Jun 2020 06:16:30 -0700 (PDT), Lee Nowell
wrote:

Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev.

When you say 'runs / unevenly' do you mean across the whole rev range?

Many mowers have a simple flap regulator to stop the engine from
stalling. It controls the throttle via a flap the sits in it's own
cooling air flow, generated by the fins on the end of the magneto /
flywheel.

When you set the throttle it is set via this 'regulation' (using a
light spring usually) so that it would try to increase the throttle
with both at tickover and under power, should it be required.

So, this means they do seem to 'hunt', at tickover especially as the
feedback loop is quite slow.

If you give it some throttle and actually cut grass with it and it
does so whilst holding a reasonably (but not completely) steady RPM
I'd say that was ok? ;-)

Cheers, T i m

On Monday, 22 June 2020 14:34:32 UTC+1, T i m wrote:

Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev.

When you say 'runs / unevenly' do you mean across the whole rev range?

Many mowers have a simple flap regulator to stop the engine from
stalling. It controls the throttle via a flap the sits in it's own
cooling air flow, generated by the fins on the end of the magneto /
flywheel.

When you set the throttle it is set via this 'regulation' (using a
light spring usually) so that it would try to increase the throttle
with both at tickover and under power, should it be required.

So, this means they do seem to 'hunt', at tickover especially as the
feedback loop is quite slow.

If you give it some throttle and actually cut grass with it and it
does so whilst holding a reasonably (but not completely) steady RPM
I'd say that was ok? ;-)

Cheers, T i m

Thanks Tim... Unfortunately my mower is much simpler than that It doesn't have any throttle for the user just an on/ off lever and another to activate the wheels.

This is a link to the manual

http://www.servicelink.org.uk/sites/...s/aee94956.pdf.

As you say... I guess if it starts, runs and cuts grass what's not to like I guess given I am in "get mower working" mode was thinking I would sort any problems now. Otherwise knowing me I will just leave it as it is with a potential of more aggravation in the future.

On Monday, 22 June 2020 14:16:33 UTC+1, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?





It may be fitted with an "air governor" This keeps the motor at a constant speed.
Just a flap in the cooling air flow attached to the carburetor.
Linkage may be sticking a bit and need freeing off.

On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

Check the carb jet isn't partially blocked and (as others have said)
that the regulator (probably a vane operating the carb butterfly,
counterbalanced by a spring) moves freely. There is usually a flap on
the carb gasket that acts as a pump, this ages and leads to hunting -
easily fixed by replacing the gasket (two or three quid from fleabay).

On Monday, 22 June 2020 14:50:07 UTC+1, Lee Nowell wrote:
On Monday, 22 June 2020 14:34:32 UTC+1, T i m wrote:

Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev.

When you say 'runs / unevenly' do you mean across the whole rev range?

Many mowers have a simple flap regulator to stop the engine from
stalling. It controls the throttle via a flap the sits in it's own
cooling air flow, generated by the fins on the end of the magneto /
flywheel.

When you set the throttle it is set via this 'regulation' (using a
light spring usually) so that it would try to increase the throttle
with both at tickover and under power, should it be required.

So, this means they do seem to 'hunt', at tickover especially as the
feedback loop is quite slow.

If you give it some throttle and actually cut grass with it and it
does so whilst holding a reasonably (but not completely) steady RPM
I'd say that was ok? ;-)

Cheers, T i m

Thanks Tim... Unfortunately my mower is much simpler than that It doesn't have any throttle for the user just an on/ off lever and another to activate the wheels.

This is a link to the manual

http://www.servicelink.org.uk/sites/...s/aee94956.pdf.

As you say... I guess if it starts, runs and cuts grass what's not to like I guess given I am in "get mower working" mode was thinking I would sort any problems now. Otherwise knowing me I will just leave it as it is with a potential of more aggravation in the future.

It IS fitted with a governor item 2 on the drawing.

On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

well it prolly has a governor and they can get sticky

look for that and see



--
There is something fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact.

Mark Twain

On Monday, 22 June 2020 16:54:46 UTC+1, The Natural Philosopher wrote:
On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

well it prolly has a governor and they can get sticky

look for that and see



--
There is something fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact.

Mark Twain

Looks like Harry was correct - thanks. It does have a speed governor. I have tried moving it with the engine running and it does change the revs although at the lowest end it seems like it may stall. Also, the lumpy running is evident no matter what I set it to.

It seems to move freely and the last 25% of the levers movement at the "fast" end doesn't seem to make any difference. Not sure if this tells us anything though

On Monday, 22 June 2020 15:39:19 UTC+1, wrote:
On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

Check the carb jet isn't partially blocked and (as others have said)
that the regulator (probably a vane operating the carb butterfly,
counterbalanced by a spring) moves freely. There is usually a flap on
the carb gasket that acts as a pump, this ages and leads to hunting -
easily fixed by replacing the gasket (two or three quid from fleabay).

In terms of the carb, When I remove the air filter, what I believe to be the carb is a plastic looking chamber but no flaps or anything. Is the suggestion here to get some fine wire or something to poke into the holes/ jets to remove any possible debris? For what its worth the carb looks fairly clean.

On Mon, 22 Jun 2020 07:40:31 -0700 (PDT), harry
wrote:

On Monday, 22 June 2020 14:50:07 UTC+1, Lee Nowell wrote:
On Monday, 22 June 2020 14:34:32 UTC+1, T i m wrote:

Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev.

When you say 'runs / unevenly' do you mean across the whole rev range?

Many mowers have a simple flap regulator to stop the engine from
stalling. It controls the throttle via a flap the sits in it's own
cooling air flow, generated by the fins on the end of the magneto /
flywheel.

When you set the throttle it is set via this 'regulation' (using a
light spring usually) so that it would try to increase the throttle
with both at tickover and under power, should it be required.

So, this means they do seem to 'hunt', at tickover especially as the
feedback loop is quite slow.

If you give it some throttle and actually cut grass with it and it
does so whilst holding a reasonably (but not completely) steady RPM
I'd say that was ok? ;-)

Cheers, T i m

Thanks Tim... Unfortunately my mower is much simpler than that It doesn't have any throttle for the user just an on/ off lever and another to activate the wheels.

This is a link to the manual

http://www.servicelink.org.uk/sites/...s/aee94956.pdf.

As you say... I guess if it starts, runs and cuts grass what's not to like I guess given I am in "get mower working" mode was thinking I would sort any problems now. Otherwise knowing me I will just leave it as it is with a potential of more aggravation in the future.

It IS fitted with a governor item 2 on the drawing.

TBF, Lee didn't say it wasn't fitted with a governor, but that it
didn't have a user throttle (except it does, the Tortoise and Hare
lever that (probably) manages the governor). ;-)

What it doesn't have is a handlebar mounted throttle.

Cheers, T i m

Thought it might be useful to send some pictures of the carb and the governor thing.

https://drive.google.com/folderview?...OYkgOxzDuhTx3O

The springs in the picture seem loose when the engine is switched off (can't see them with engine on as underneath the air filter). Almost like they don't do anything. Having said that the governor seems to work but not sure if these are related. Also, having now seen the springs, in the back of my mind I vaguely remember buying new springs in an attempt to fix a (probably similar) issue so maybe I fitted them incorrectly?

On Mon, 22 Jun 2020 09:48:39 -0700 (PDT), Lee Nowell
wrote:

On Monday, 22 June 2020 16:54:46 UTC+1, The Natural Philosopher wrote:
On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

well it prolly has a governor and they can get sticky

look for that and see



--
There is something fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact.

Mark Twain

Looks like Harry was correct - thanks. It does have a speed governor.

I think that's what we would normally call 'a throttle' and that in
turn (on lawnmowers) is normally connected to the *actual* throttle
via a spring / linkage / governor.

I have tried moving it with the engine running and it does change the revs although at the lowest end it seems like it may stall.

It shouldn't, assuming it's running correctly and the governor is
working correctly.

Also, the lumpy running is evident no matter what I set it to.

It's difficult to understand what you are describing as 'lumpy' with a
single cylinder lawnmower engine Lee. What you might be describing as
'lumpy' is in fact hunting and that can be quite normal, depending on
the make / model of the engine etc.

It seems to move freely and the last 25% of the levers movement at the "fast" end doesn't seem to make any difference.

No, it probably wouldn't because 1) it's a very crude machine (in
general) and 2) the governor that linkage is probably connected to may
not be correctly adjusted or running freely.

Not sure if this tells us anything though

No, it doesn't really. ;-)

Recap. The actual carb throttle mech (often a butterfly) is connected
via a rod / spring(s) to a paddle / vane that sits in the airflow for
the ducted cooling system. If the engine starts to labour though some
long grass the revs drop in comparison with the user set throttle and
the flap relaxes, allowing the throttle to open and the engine run
faster. If the load comes off the revs increase and the flap pulls the
throttle closed slightly, managing the revs.

However, as mentioned elsewhere, excessive 'hunting' or poor throttle
response could be down to / aggravated by other issues.

If you look closely into the area around the carb you might see a rod
going off towards the cooling ducting and if moved carefully should
move freely. Often springs can jet unhooked or stretched and that can
also impact how well it all works.

If you could find and safely operate the actual carb lever by hand
when the engine is running you should be able to hold the revs
constant or adjust them more like a conventional throttle.

Cheers, T i m

On 22/06/2020 17:48, Lee Nowell wrote:
the lumpy running is evident no matter what I set it to.
dirt in the needle valves or a sticky valve then


--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly

On Mon, 22 Jun 2020 10:14:39 -0700 (PDT), Lee Nowell
wrote:

Thought it might be useful to send some pictures of the carb and the governor thing.

They speak 1000 words. ;-)

https://drive.google.com/folderview?...OYkgOxzDuhTx3O

Hmm, I'd have to compare that with a formal manual picture to compare.

The springs in the picture seem loose when the engine is switched off (can't see them with engine on as underneath the air filter).

That can be right, depending on the throttle position.

Almost like they don't do anything.

They may not at the beginning because 1) the throttle isn't set (off
tortoise) and 2) the engine isn't running and the flap isn't pulling
against the spring.

Having said that the governor seems to work but not sure if these are related.

As mentioned elsewhere, you should be able to operate the throttle
itself (not the lever on the outside) directly with the engine running
and that should have a more direct relationship with the engine revs.

Also, having now seen the springs, in the back of my mind I vaguely remember buying new springs in an attempt to fix a (probably similar) issue so maybe I fitted them incorrectly?

They do look quite new and quite possibly (they are often a bit of a
puzzle and often not intuitive).

Cheers, T i m

On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

Fit a new spark plug.

--
Ask how to email me.

On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

If fitting a new spark plug does not fix it the next step is to fit a
carburettor overhaul kit. There are various rubber bits, jets and
filters that periodically need changing.
Usually found when it does not start after a winter "resting". :-)


--
Ask how to email me.

Thanks for the great explanation. Any idea how I find the actual throttle? Is it the silver thing too right in picture 3 which has a "rod" connecting it to the black governor?

From the pictures which are the needle valves/ valves I should check and how do I clean / fix them

On Mon, 22 Jun 2020 11:09:50 -0700 (PDT), Lee Nowell
wrote:

Thanks for the great explanation.

Not sure it was great as in details but should cover the basic
operation. ;-)

Any idea how I find the actual throttle? Is it the silver thing too right in picture 3 which has a "rod" connecting it to the black governor?

It will be the bit that looks like it's going into the carb somewhere,
in the main airflow from the airfilter in (I can't really make it out
from the photos).

Cheers, T i m

On 22/06/2020 17:51, Lee Nowell wrote:
On Monday, 22 June 2020 15:39:19 UTC+1, wrote:
On 22/06/2020 14:16, Lee Nowell wrote:
Hi All,

A quick update on my mower - thought I would start a new thread in case the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs very unevenly. It doesn't sound like it is likely to stall but runs what I would call lumpy with an uneven rev. As advised here, I did the following before firing it up...
1. Checked the plug. It was clean with no residue. I checked the gap and it was about 21 thousandths inch. The manual says either 20 or 30 but I can't tell which one I have to know for sure
2. The air filter is mostly spotlessly clean but a little but of what looks like oil on the inlet side where the holes of the casing are
3. The petrol tank had a tiny bit of fuel left in it (not enough to pump with the priming bulb) so have put fresh fuel in with the dribble that was there
4. No smoke seen of any colour or noticeable smell

Anyone have any idea where I should go from here?

Thanks

Lee.

Check the carb jet isn't partially blocked and (as others have said)
that the regulator (probably a vane operating the carb butterfly,
counterbalanced by a spring) moves freely. There is usually a flap on
the carb gasket that acts as a pump, this ages and leads to hunting -
easily fixed by replacing the gasket (two or three quid from fleabay).

In terms of the carb, When I remove the air filter, what I believe to be the carb is a plastic looking chamber but no flaps or anything. Is the suggestion here to get some fine wire or something to poke into the holes/ jets to remove any possible debris? For what its worth the carb looks fairly clean.

The carb will be the only thing between the air filter and the engine
intake. They (usually) are in two halves, the gasket between the halves
is the one that may need replacing. TBH new carbs are surprisingly cheap
from China.

On Mon, 22 Jun 2020 11:11:12 -0700 (PDT), Lee Nowell
wrote:

From the pictures which are the needle valves/ valves

It probably doesn't have a needle valve as they would normally be
associated with a slide throttle carb.

I should check and how do I clean / fix them

As mentioned elsewhere, you have to be careful about poking things
though jets as you can easily open them out so a good spray with carb
cleaner to try to dissolve any residues and dislodge any debris.

This will normally mean taking the carb off and getting it on the
bench although you might be able to get sufficient access in place to
do a basic clean of you can get any input filters off.

The bottom line though is if it runs well enough to cut reasonable
length grass, that would suggest it was running reasonably well?

If it simply doesn't tickover smoothly but the revs hunt up and down
it could be running properly?

Cheers, T i m

On Mon, 22 Jun 2020 11:09:50 -0700 (PDT), Lee Nowell
wrote:

Thanks for the great explanation. Any idea how I find the actual throttle? Is it the silver thing too right in picture 3 which has a "rod" connecting it to the black governor?

As a sort of aside, this talks of the springs and the other carb
related issues as mentioned elsewhe

https://youtu.be/NDMR--XhC8g?list=PL...CHp-L7hGv7&t=5

Cheers, T i m

On Mon, 22 Jun 2020 20:38:17 +0100, T i m wrote:

The bottom line though is if it runs well enough to cut reasonable
length grass, that would suggest it was running reasonably well?

If it simply doesn't tickover smoothly but the revs hunt up and down
it could be running properly?

I have a Briggs&Stratton-powered cheap genset.

It hunts (vroom-vroom-vroom-vroom) when not electrically loaded, i.e. very
little mechanical load. Put a bit of load on it and it settles down.

OTOH, if you aren't sure you have attached the governor springs right: check
that. I tried to replace a missing spring with random springs selected from the
random spring box, and it didn't run anything like nearly right until I bought a
(surprisingly expensive) replacement part. Lever length, hardness, spring length
need to be spot-on, or very close. And there's usually a line of holes in which
the bits hook, get a wrong hole and you have just set it to "perfect for a
snowblower in the tropics" or whatever.


Thomas Prufer

On 23/06/2020 06:53, Thomas Prufer wrote:
On Mon, 22 Jun 2020 20:38:17 +0100, T i m wrote:

The bottom line though is if it runs well enough to cut reasonable
length grass, that would suggest it was running reasonably well?

If it simply doesn't tickover smoothly but the revs hunt up and down
it could be running properly?

I have a Briggs&Stratton-powered cheap genset.

It hunts (vroom-vroom-vroom-vroom) when not electrically loaded, i.e. very
little mechanical load. Put a bit of load on it and it settles down.

OTOH, if you aren't sure you have attached the governor springs right: check
that. I tried to replace a missing spring with random springs selected from the
random spring box, and it didn't run anything like nearly right until I bought a
(surprisingly expensive) replacement part. Lever length, hardness, spring length
need to be spot-on, or very close. And there's usually a line of holes in which
the bits hook, get a wrong hole and you have just set it to "perfect for a
snowblower in the tropics" or whatever.


Thomas Prufer

spent 2 hrs trying to find out why my old revox turntable was
hunting...until I put the heavy platter back on, and it settled down
steady as a rock :-)

system theory and feedback stability mate. Too much negative feedback
and a little delay causes oscillations.

It's why the EU is hopeless. Too much administrative inertia to respond
to any changes. Not economic, not social, not medical...


You NEED localised feedback in any complex system with the minimum
amount of overall feedback.


--
Any fool can believe in principles - and most of them do!

If its any consolation, most of the locals around here seem to have mowers
that hunt most or all of the time and they cut grass fine.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Lee Nowell" wrote in message
...
On Monday, 22 June 2020 14:34:32 UTC+1, T i m wrote:

Hi All,

A quick update on my mower - thought I would start a new thread in case
the specifics helps someone else in the future

The mower started first time - I was amazed. However... The engine runs
very unevenly. It doesn't sound like it is likely to stall but runs what
I would call lumpy with an uneven rev.

When you say 'runs / unevenly' do you mean across the whole rev range?

Many mowers have a simple flap regulator to stop the engine from
stalling. It controls the throttle via a flap the sits in it's own
cooling air flow, generated by the fins on the end of the magneto /
flywheel.

When you set the throttle it is set via this 'regulation' (using a
light spring usually) so that it would try to increase the throttle
with both at tickover and under power, should it be required.

So, this means they do seem to 'hunt', at tickover especially as the
feedback loop is quite slow.

If you give it some throttle and actually cut grass with it and it
does so whilst holding a reasonably (but not completely) steady RPM
I'd say that was ok? ;-)

Cheers, T i m

Thanks Tim... Unfortunately my mower is much simpler than that It
doesn't have any throttle for the user just an on/ off lever and another to
activate the wheels.

This is a link to the manual

http://www.servicelink.org.uk/sites/...s/aee94956.pdf.

As you say... I guess if it starts, runs and cuts grass what's not to like
I guess given I am in "get mower working" mode was thinking I would sort
any problems now. Otherwise knowing me I will just leave it as it is with a
potential of more aggravation in the future.

Lee Nowell explained :
Is the suggestion here to get some fine wire or something to poke into the
holes/ jets to remove any possible debris?

No, don't do that, you will damage them. If any jets are obstructed,
blow them clear with compressed air, or a tyre pump.

On 23/06/2020 09:15, Harry Bloomfield wrote:
Lee Nowell explained :
Â*Is the suggestion here to get some fine wire or something to poke
into the holes/ jets to remove any possible debris?

No, don't do that, you will damage them. If any jets are obstructed,
blow them clear with compressed air, or a tyre pump.

Two sorts of blockages happen in carbs.
1/. Bits of grit. Blow them out
2/. Gum from evaporated stale petrol or petroil. Rinse in fresh petrol

--
Canada is all right really, though not for the whole weekend.

"Saki"

On 22/06/2020 18:57, Kellerman wrote:
Anyone have any idea where I should go from here?

I had to do a rebuild on mine several years back as wife tried to cut a
drain cover with it. :-)
Once it was rebuilt I remember a similiar problem and although I cant
now remember the specifics it was sorted by adjusting the spring tension
and governor flap.

On 22/06/2020 20:21, wrote:
the gasket between the halves is the one that may need replacing.

The most common failure IMHO. Modern bio-petrols seem to rot them
away every 5 years or so.

Hi all,

I have now uploaded a couple of videos and another photo to the same place

https://drive.google.com/folderview?...OYkgOxzDuhTx3O

There is a video of me moving the vane which shows that one of the springs on the governor seems to do nothing. Maybe I should shorten it a bit - but how much?

There are 2 other videos with the engine running on fastest and one on slowest. Thought it might help to hear the engine running.

Thanks all for your help

Lee

On Tue, 23 Jun 2020 04:43:34 -0700 (PDT), Lee Nowell
wrote:

There is a video of me moving the vane which shows that one of the springs on the governor seems to do nothing.

That looks odd -- as in wrong spring or wrong place. But I have been wrong
before.

Maybe I should shorten it a bit - but how much?

Not unless you are prepared to buy a new one! IME, it opens up the way to many
new ways of not running right, most with a racing engine, or one that dies under
load.

There are 2 other videos with the engine running on fastest and one on slowest. Thought it might help to hear the engine running.

Sounds pretty much OK, I'd say?

Does it mow?


Thomas Prufer

On Thu, 25 Jun 2020 08:19:26 +0200, Thomas Prufer wrote:

Maybe I should shorten it a bit - but how much?

Not unless you are prepared to buy a new one! IME, it opens up the way
to many new ways of not running right, most with a racing engine, or one
that dies under load.

Or refuses to run at all. The springs/counter springs between the
vane, actual throttle arm and the throttle control lever are a very
dynamic system. There is very little corelation between what things
are like with/without the engine running. Bottom line don't fiddle
....

There are 2 other videos with the engine running on fastest and
one on slowest. Thought it might help to hear the engine running.

Sounds pretty much OK, I'd say?

Aye, the slowest is hunting a bit, does that go away when mowing? Who
uses the slowest speed anyway?

The fast seems OK. Does it hold speed when moving from cut/short
grass to long grass with just a change in engine note as it throttles
up to match the increased load?

My mower started hunting really badly (almost flat out down to almost
stalling) and didn't settle down under load. One of the little flap
valves made from the gasket between fuel tank and carb had got itself
out of position. Repositioned and carefully reassembled and it's been
fine since, 5 years or so...

TBH with the OPs mower it's borderline "it ain't' broke, don't fix
it".

--
Cheers
Dave.

Sorry all for the delay in responding. The lawn treatment folks came the other day and put some pellets on the lawn which apparently needs to be watered in before mowing. Forecast is some rain this weekend so will try the mower next week and report back.

Glad to hear the mower in fast sounds ok. So fingers crossed it mows ok. There are some patches of longish thick grass so should give it a good test.

On 22/06/2020 18:03, T i m wrote:


What it doesn't have is a handlebar mounted throttle.


Many mowers these days don't have a user throttle even in the guise of a
Tortoise and Hare lever.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 22/06/2020 18:14, Lee Nowell wrote:
Thought it might be useful to send some pictures of the carb and the governor thing.

https://drive.google.com/folderview?...OYkgOxzDuhTx3O

The springs in the picture seem loose when the engine is switched off

They tend to be very weak springs which may appear to be loose.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 22/06/2020 15:08, Chris Hogg wrote:

I have had a similar problem a few times in the past. The solution
that works for me is to dismantle the fuel tank - carb combination and
give it a thorough clean out. It's surprising how much crud builds up
on the little gauze fuel filters over the years.


I've found when doing this its worth buying a casket kit first.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 23/06/2020 12:43, Lee Nowell wrote:
Hi all,

I have now uploaded a couple of videos and another photo to the same place

https://drive.google.com/folderview?...OYkgOxzDuhTx3O

There is a video of me moving the vane which shows that one of the springs on the governor seems to do nothing. Maybe I should shorten it a bit - but how much?

There are 2 other videos with the engine running on fastest and one on slowest. Thought it might help to hear the engine running.

Thanks all for your help

Lee


https://www.youtube.com/watch?v=_0ks74iKMdY

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 27/06/2020 07:40, alan_m wrote:
On 22/06/2020 15:08, Chris Hogg wrote:

I have had a similar problem a few times in the past. The solution
that works for me is to dismantle the fuel tank - carb combination and
give it a thorough clean out. It's surprising how much crud builds up
on the little gauze fuel filters over the years.


I've found when doing this its worth buying a casket kit first.

In case you cremate yourself?


--
€œBut what a weak barrier is truth when it stands in the way of an
hypothesis!€�

Mary Wollstonecraft

On 27/06/2020 07:35, alan_m wrote:
On 22/06/2020 18:03, T i m wrote:


What it doesn't have is a handlebar mounted throttle.


Many mowers these days don't have a user throttle even in the guise of a
Tortoise and Hare lever.

As an EX GF said give it 'maximum rabbit'....


--
€œBut what a weak barrier is truth when it stands in the way of an
hypothesis!€�

Mary Wollstonecraft

Quick update. I managed to mow the lawn over the weekend including an area of long (say 6") densely populated grass without any troubles. So based on the various feedback here thing I should leave the mower as is.

Thanks for all your help

Lee.