have you checked to see if spark is at plug......done by holding plug onto
head by insulated (recomended) pliers and seeing if spark is present when
engine is turned over.

pat
"mutley" wrote in message
...
Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated
to
them?

The Q is if the flywheel magneto may function perfectly when cold, but
fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

--
Any help TIA
Please reply to Newsgroup
scrambled address

mutley wrote:
Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated to
them?

The Q is if the flywheel magneto may function perfectly when cold, but fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

Possible condenser problem? Note, with small high-perormance
engines like this, the plug is critical - have you tried a
brand-new one? I've seen a few "plug is OK" jobs where there's
a problem with same.

In an earlier contribution to this discussion,
mutley wrote:

Can anyone advise on 2-stroke engines? or is there a newsgroup
dedicated to them?

The Q is if the flywheel magneto may function perfectly when cold,
but fail when hot. I have a Stihl tool which starts and runs fine,
but if it stalls when hot refuses to start again. Fuel is OK, as is
spark plug.

2-stroke engines can often be a pain to start or re-start - even when
everything is in order!

Have you checked whether the plug is actually sparking? [Take the plug out
and lie it on top of the engine. Re-connect the ignition lead. Make sure
that the body of the plug is making good electrical contact with the
cylinder head - using a wire with large croc clips on if necessary. Pull the
cord, and watch the plug's spark gap. If there is a good spark, the magneto
is ok].
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated to
them?

The Q is if the flywheel magneto may function perfectly when cold, but fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

--
Any help TIA
Please reply to Newsgroup
scrambled address

"mutley" wrote in message


Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated to
them?

The Q is if the flywheel magneto may function perfectly when cold, but fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

And you are using the correct mixture?

I know that lawn mowers go out of timing after hitting roots or stones.
Is it possible your chain saw is out of timing? No idea how it might
happen though. But that is what it sounds like.


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

On Mon, 12 Sep 2005 15:41:19 UTC, "mutley" wrote:

Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated to
them?

The Q is if the flywheel magneto may function perfectly when cold, but fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

Classic symptom (IME) of a condenser problem.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://laminateflooring.oncloud8.com

"mutley" wrote in message
...
Can anyone advise on 2-stroke engines? or is there a newsgroup dedicated
to
them?

The Q is if the flywheel magneto may function perfectly when cold, but
fail
when hot. I have a Stihl tool which starts and runs fine, but if it stalls
when hot refuses to start again. Fuel is OK, as is spark plug.

--
yes the magneto can fail when hot but be working when cold I had this on a
seagull outboard it took me age to find it!!

The Q

I'm not convinced it is an electrics problem. If it were then it would
most likely stop running once hot.

First the obvious - I trust you aren't putting choke on when restarting
it while hot?

Next, check the tuning - should be 1 and 1.

Next, how is the compression?. It is hard to describe what to look for
- you sort of know through experience. When pulling the engine over
slowly you should be able to feel the compression resisting the pull.
It should be reasonably strong. Try this both hot and cold.

Try that and let us know how you get on. If this doesn't work then are
there any other symptoms? Does it idle ok? What is it - a chainsaw? You
mention stalling - is this through bad use or does it just stall
itself?

Alan.

"Alan" wrote in news:1126626730.822726.93670
@g44g2000cwa.googlegroups.com:

Not neccersarily the solution to your problem but a lot of Stihl machines
have a gauze spark arrestor in the exhaust that after a time can clog this
will lead to loss of power and stalling

Chris

"Chris Selwyn-Smith" wrote in
message . 254.254...
"Alan" wrote in news:1126626730.822726.93670
@g44g2000cwa.googlegroups.com:

Not neccersarily the solution to your problem but a lot of Stihl machines
have a gauze spark arrestor in the exhaust that after a time can clog this
will lead to loss of power and stalling

Chris


And people often take the _crankcase_ compression for granted.

Sylvain.

On Thu, 15 Sep 2005 18:31:50 +0000 (UTC), "Chris Selwyn-Smith"
wrote:

"Alan" wrote in news:1126626730.822726.93670
:

Not neccersarily the solution to your problem but a lot of Stihl machines
have a gauze spark arrestor in the exhaust that after a time can clog this
will lead to loss of power and stalling

I had similar (exhaust mesh bunged up) on my BIL's strimmer but that
wouldn't 'rev' when cold either?

All the best ..

T i m

Thanks for all the helpful replies from everyone. I can answer some of the
suggestions:

It's an 85 hedgecutter and I am leaving choke open when trying to re-start

Compression seems OK in comparison with other 2-stroke machines which I
have.

Idling is OK when cold but when hot I have to have the idle screw turned
right down to keep it running, but it still stalls by itself. It will only
keep running when hot if I keep the throttle almost fully open and the
engine running fast.

"Alan" wrote in message
ups.com...
[snip]
Next, check the tuning - should be 1 and 1.

I'm unsure what you mean by this??

Re. the plug: can someone give the correct plug type and grade for an HS-85?
I don't have a user manual for this.

I'll try the other tests suggested and report back! At present I can only
work it for about 10/15 minutes at a time, which is frustrating.

regards to all,
mutley

The carburettor has 2 tuning screws.
These should be tightened (not too tight!) and then slackened 1 turn
(ie 360 degrees) to give the correct tuning.
If this doesn't work, judging by your symptoms, you can try opening the
low speed screw (the one nearest the engine block) a little (1/4 a turn
or so)

I don't think it is the gauze in the exhaust (spark arrester) as that
would prevent it revving as the previous poser says. A clogged fuel
filter would have the same symptoms.
Are you sure the fuel is OK? - stale fuel is a common problem with
similar symptoms. Have you tried emptying the fuel tank and using
freshly bought fuel - run it for a minute or so to clear out any old
fuel?

As another poster says, crankcase pressure can cause problems but IME
this prevents running completely and is a very rare occurrence.

I don't know which plug this machine takes. I would pop into your local
friendly independent garden machinery repair place with the old one and
they will give you a new one to match.

I'm not convinced about the plug being the problem either. I think that
if the tuning or fuel doesn't sort it then I would have it
professionally looked at in your local repair place. My money is on a
carburettor problem. Please let me know what the problem is. I am
intrigued.

Alan.

Thanks again for the helpful reply.

"Alan" wrote in message
The carburettor has 2 tuning screws.

There is only one on my machine (which I think is a 2001 model) and it's
marked 'H......L' on a circle.

My much older Stihl 015AV chainsaw has 2 screws as you remark.

These should be tightened (not too tight!) and then slackened 1 turn
(ie 360 degrees) to give the correct tuning.
If this doesn't work, judging by your symptoms, you can try opening the
low speed screw (the one nearest the engine block) a little (1/4 a turn
or so)

I don't think it is the gauze in the exhaust (spark arrester) as that
would prevent it revving as the previous poser says. A clogged fuel
filter would have the same symptoms.
Are you sure the fuel is OK? - stale fuel is a common problem with
similar symptoms. Have you tried emptying the fuel tank and using
freshly bought fuel - run it for a minute or so to clear out any old
fuel?

Thanks, I'll try that although I thought that I was using recently purchased
fuel.

I'm not convinced about the plug being the problem either. I think that
if the tuning or fuel doesn't sort it then I would have it
professionally looked at in your local repair place. My money is on a
carburettor problem. Please let me know what the problem is. I am
intrigued.

I have noticed that the black ?plastic? flange where the carb. fixes onto
the cylinder body has a hairline crack in it - I'm wondering if too much air
is getting in, but to me that would seem to show up at bad starting -- it
starts easily enough.

regards,
Mutley

Hi,

I've not much experience with modern machines but IIRC, you are
prevented from changing the tuning by much on these modern carbs so I
guess that eliminates that problem.

The hairline crack is interesting - It would be worth popping the carb
off and checking it out further as this may affect fuel flow. I would
definitely replace it - you will have to anyway, even if that isn't
your current problem, and see how you get on with that.

Keep us updated.

Alan.