From Newsgroup: uk.rec.motorcycles

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by
mistake once. That was some time ago and it was fine again after I go
rid of the diesel. Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?
--
/Simon
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From Newsgroup: uk.rec.motorcycles

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by mistake once. That was some time ago and it was fine again after I go
rid of the diesel.-a Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?

I had two B & S engined machines at 'the chateau'. One ride on mower,
one three-wheeled brush cutter.

I certainly had the blocked fuel cap vent issue on the brush cutter
once, but you have eliminated that.

Weird that it will run OK on ether, or I would be thinking spark loss
due to heating of the ignition 'winding' breaking down the insulation. I
think ether doesn't need such a strong spark.

Can you get a 'softer' or fancy electrode material plug in the same
size? Or test the resistance of the winding when hot?
--
Moto Morini 2C/375
Gilera 175 Sport, Husqvarna 401 Svartpilen
Honda CB250RS (Not Waynetta!)
"Do not adjust your mind, there is a fault in the reality"
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From Newsgroup: uk.rec.motorcycles

On 12/05/2026 19:49, Peter Fisher wrote:

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again
immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by
mistake once. That was some time ago and it was fine again after I go
rid of the diesel.-a Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?

I had two B & S engined machines at 'the chateau'. One ride on mower,
one three-wheeled brush cutter.

I certainly had the blocked fuel cap vent issue on the brush cutter
once, but you have eliminated that.

Weird that it will run OK on ether, or I would be thinking spark loss
due to heating of the ignition 'winding' breaking down the insulation. I think ether doesn't need such a strong spark.

Can you get a 'softer' or fancy electrode material plug in the same
size? Or test the resistance of the winding when hot?

Yeah the igniter thingy is just about the only thing left. Or something
with the valves again. Or an air leak (can't find one).

One thing I left out - it seemed to need choke all the time when it was running, so there's something up. Feels like an air leak now I'm
thinking about it, but no idea where.
--
/Simon

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From Newsgroup: uk.rec.motorcycles

Simon Wilson <simowilso+newsdemon@nodamnspamn.gmail.com> wrote:

On 12/05/2026 19:49, Peter Fisher wrote:

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again
immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by
mistake once. That was some time ago and it was fine again after I go
rid of the diesel.a Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?

I had two B & S engined machines at 'the chateau'. One ride on mower,
one three-wheeled brush cutter.

I certainly had the blocked fuel cap vent issue on the brush cutter
once, but you have eliminated that.

Weird that it will run OK on ether, or I would be thinking spark loss
due to heating of the ignition 'winding' breaking down the insulation. I
think ether doesn't need such a strong spark.

Can you get a 'softer' or fancy electrode material plug in the same
size? Or test the resistance of the winding when hot?

Yeah the igniter thingy is just about the only thing left. Or something
with the valves again. Or an air leak (can't find one).

One thing I left out - it seemed to need choke all the time when it was running, so there's something up. Feels like an air leak now I'm
thinking about it, but no idea where.

The fact that you can run it continuously on ether would seem to
indicate to me, that it is not a spark related issue. But Pete's point
about ether not needing such a strong spark might be true as well,
but doesn't explain why it readily starts again after stopping.

Needing the choke on all the time to run normally means it's a fuel
delivery or fuel mixture problem for sure.

There isn't that much to these things, head off, look for anything
suspect, check valve lash, check compression, spray something around
the carb isolater/gasket to check for an air leak, ???


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From Newsgroup: uk.rec.motorcycles

Simon Wilson <simowilso+newsdemon@nodamnspamn.gmail.com> wrote in news:18aee4e3fd319b2b$16254$2895151$52d51861@news.newsdemon.com:

WTF is wrong with it?

fucked, innit

it is pining for a skip

maybe have a ceremony first, involving Swan Vesta, before you grant its
final wish
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From Newsgroup: uk.rec.motorcycles

Simon Wilson <simowilso+newsdemon@nodamnspamn.gmail.com> wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

I can keep it running continuously on ether.

Will it keep running indefinitely on gasoline? As others have
observed, ether is easier to ignite than gasoline. If gasoline
dribbled into the intake keeps it running then it sounds like
some obscure fuel restriction.

If it'll keep running _only_ on ether, but not gasoline by any
route, then it could be something really obscure like rings
that leak more when warm and the oil is thin.....

Any chance a decompression mechanism is malfunctioning?

Possibly a loose magneto stator? If the air gap shifts that
will affect the spark. An inline spark checker might be
informative. Same for the breaker points if it uses them.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by mistake once. That was some time ago and it was fine again after I go
rid of the diesel. Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

A valve that hangs up when warm seems a possibility, how it might
happen eludes me, however.

Have you done compression checks warm and cold?

hth,

bob prohaska

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From Newsgroup: uk.rec.motorcycles

On 12/05/2026 21:09, Simon Wilson wrote:

On 12/05/2026 19:49, Peter Fisher wrote:

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again
immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by
mistake once. That was some time ago and it was fine again after I go
rid of the diesel.-a Another time it loast all compresson when I ran
it on old fuel - that was a valve that got stuck.

WTF is wrong with it?

I had two B & S engined machines at 'the chateau'. One ride on mower,
one three-wheeled brush cutter.

I certainly had the blocked fuel cap vent issue on the brush cutter
once, but you have eliminated that.

Weird that it will run OK on ether, or I would be thinking spark loss
due to heating of the ignition 'winding' breaking down the insulation.
I think ether doesn't need such a strong spark.

Can you get a 'softer' or fancy electrode material plug in the same
size? Or test the resistance of the winding when hot?

Yeah the igniter thingy is just about the only thing left. Or something
with the valves again. Or an air leak (can't find one).

One thing I left out - it seemed to need choke all the time when it was running, so there's something up. Feels like an air leak now I'm
thinking about it, but no idea where.

Oh well, that seems significant. What is the history of the mower -
acquired from new? The new carb is presumably the correct one for that
engine or just replaced to match what was already on it ? That ought to
rule out a blocked jet but not an incorrect one IYSWIM . The restarting immediately is the real mystery. A heat related ignition issue should
need it to cool down a bit first.

A new cheap pattern ignition coil/igniter might still be worth a try.
--
Moto Morini 2C/375
Gilera 175 Sport, Husqvarna 401 Svartpilen
Honda CB250RS (Not Waynetta!)
"Do not adjust your mind, there is a fault in the reality"
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.rec.motorcycles

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

Surely
"Shit in the carbs"

HTH
:-)
--
Bruce Porter
"The internet is a huge and diverse community but mainly friendly" http://ytc1.blogspot.co.uk/
There *is* an alternative! http://www.openoffice.org/
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From Newsgroup: uk.rec.motorcycles

On 13/05/2026 07:43, Peter Fisher wrote:

On 12/05/2026 21:09, Simon Wilson wrote:

On 12/05/2026 19:49, Peter Fisher wrote:

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again
immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel
by mistake once. That was some time ago and it was fine again after
I go rid of the diesel.-a Another time it loast all compresson when I >>>> ran it on old fuel - that was a valve that got stuck.

WTF is wrong with it?

I had two B & S engined machines at 'the chateau'. One ride on mower,
one three-wheeled brush cutter.

I certainly had the blocked fuel cap vent issue on the brush cutter
once, but you have eliminated that.

Weird that it will run OK on ether, or I would be thinking spark loss
due to heating of the ignition 'winding' breaking down the
insulation. I think ether doesn't need such a strong spark.

Can you get a 'softer' or fancy electrode material plug in the same
size? Or test the resistance of the winding when hot?

Yeah the igniter thingy is just about the only thing left. Or
something with the valves again. Or an air leak (can't find one).

One thing I left out - it seemed to need choke all the time when it
was running, so there's something up. Feels like an air leak now I'm
thinking about it, but no idea where.

Oh well, that seems significant. What is the history of the mower -
acquired from new? The new carb is presumably the correct one for that engine or just replaced to match what was already on it ? That ought to
rule out a blocked jet but not an incorrect one IYSWIM . The restarting immediately is the real mystery. A heat related ignition issue should
need it to cool down a bit first.

A new cheap pattern ignition coil/igniter might still be worth a try.

No, it wasn't new. Non runner when I bought it, no spark. Replaced the magneto/coil thingy and it was fine after that.
--
/Simon
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From Newsgroup: uk.rec.motorcycles

Peter Fisher <nospam@nosspam.net> wrote:

<snip tale of woe>

The restarting
immediately is the real mystery. A heat related ignition issue should
need it to cool down a bit first.

Not necessarilyrCa

I once had a 105E Ford Anglia, that developed a serious misfire shortly
after starting. Checked everything, couldnrCOt find the source. Finally, I swapped the distributor from my dadrCOs Cortina, and all was well - so the problem lay there.

Checked everything again and again, points, points gap, dwell angle, advance/retard mechanism, couldnrCOt find anything wrong. Finally, checking again, my screwdriver caught the wire on the contact-breaker plate, and it pulled off the insulation.

And there, the only thing that was carrying the connection to the contact-breaker, was a single strand of the wirerCaand it was bright blue as the current passing through had heated it.

Replaced the wire, problem went away permanently.

IrCOm suspecting the mower issue is ignition related.
--
Spike
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From Newsgroup: uk.rec.motorcycles

On 13/05/2026 08:59, YTC1 wrote:

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again
immediately.

Surely
"Shit in the carbs"

HTH
:-)

I once had an outboard motor that displayed precisely these symptoms.
It turned out to be a tiny speck of dirt in the carb that would fall to
the bottom of the carb when not running but would be drawn up into the
jet, and bung it up{1], when running. When I finally decided to drain
the carb properly, and flush it through[2], the problem was solved.[3]

HTH

Chris

[1] technical term
[2] a terrible waste of fuel during the first fuel crisis - oh, wait...
[3] you said you changed the fuel but did you actually flush things through?
--
The Deuchars BBB#40 COFF#14
Yamaha XV750SE & Suzuki GS550T
https://www.Deuchars.org.uk
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From Newsgroup: uk.rec.motorcycles

Simon Wilson <simowilso+newsdemon@nodamnspamn.gmail.com> wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by mistake once. That was some time ago and it was fine again after I go
rid of the diesel. Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?

Random stab in the dark, but it's not something to do with E10 petrol is it?

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From Newsgroup: uk.rec.motorcycles

On May 12, 2026 at 2:29:31 PM EDT, "Simon Wilson" <simowilso+newsdemon@nodamnspamn.gmail.com> wrote:

WTF is wrong with it?

Air leak, for sure.
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From Newsgroup: uk.rec.motorcycles

On 13/05/2026 09:32, Spike wrote:

IrCOm suspecting the mower issue is ignition related.

But, but, it must be fuel.

<thinks> Oh, you're probably right.
--
/Simon
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: uk.rec.motorcycles

On 12/05/2026 19:29, Simon Wilson wrote:

Drive me mental sometimes.

Basic, simple lawnmower petrol engine. Briggs and Stratton I think.

Runs for a few seconds, maybe a minute, then stops. Will start again immediately.

I can keep it running continuously on ether.

Different spark plug, same result.
Brand new carburettor, same result.
Drained fuel, fill with fresh fuel, same result.
Run without fuel cap on, same result.
New fuel pipe, 100% not kinked, same result.
Fuel flows freely out of the float chamber.

The only slight weird history of this engine is I ran it on diesel by mistake once. That was some time ago and it was fine again after I go
rid of the diesel.-a Another time it loast all compresson when I ran it
on old fuel - that was a valve that got stuck.

WTF is wrong with it?

Magneto possibly as it warms up, but I wouldn't have thought it would
work so quickly after a stop.

Stuck valves are worth checking. Normally though you'd hear a "clack" as
it popped closed, or if it were sticking intermittently (I guess non-interference engine) you might heat a ticking of combustion gasses
leaking past plus a clacking as it finally popped closed.

Governor sticking?
--

CHUMP #1 (CHarge Up Muppet)

Pip
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From Newsgroup: uk.rec.motorcycles

On Wed, 13 May 2026 18:37:01 +0100, Simon Wilson <simowilso+newsdemon@nodamnspamn.gmail.com> wrote:

On 13/05/2026 09:32, Spike wrote:

IAm suspecting the mower issue is ignition related.

But, but, it must be fuel.

If it feels like fuel, it's ignition

If it feels like ignition, it's fuel

<thinks> Oh, you're probably right.

yep :-)
--
Champ
neal at champ dot org dot uk

I don't know, but I been told
You never slow down, you never grow old
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From Newsgroup: uk.rec.motorcycles

On 12/05/2026 21:09, Simon Wilson wrote:

One thing I left out - it seemed to need choke all the time when it was running, so there's something up. Feels like an air leak now I'm
thinking about it, but no idea where.

Blocked main jet?

Does this engine have a primer pump?

Will it run if petrol is constantly sprayed in the inlet (old perfume
bottle or kitchen spray bottle).
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