2 Stroke engine does not start

[TMC]

Old Partner s50 chain saw

It came from the garage of a deceased relative no reason to believe that it was faulty was clean outside blade sharp and tensioned

there is a spark

the plug gets wet so there is fuel delivered

no fuel in when I got it

new fuel 50:1 mix

air filter clean

tried with choke off 1/2 and full

checked that the on off switch enables disables the spark

had top off of carb diaphram fine

after drying plug and leaving the cylinder to dry it almost starts though that could be wishful thinking

getting tired of pulling the recoil starter now

any thoughts or tips

Once I have sorted this the Dolmar 309 is next

[Huge]

FWIW, IME, 2 stroke engines have a mind of their own and can be absolute bastards to start until you get them sussed out. My chainsaw's like that, especially if you're stupid enough to follow the instructions, which hopelessly flood it.

[Dave Plowman (News)]

Try it with no choke after cleaning the plug - preferably with a blow lamp.

2 strokes tend to run rich anyway, and generally don't need as much choke as a four stroke.

[DIY]

Is the plug gapped correctly?

[MuddyMike]

If you have replaced the spark plug, then it probably needs a new diaphragm in the carb.

Mike

[andrew]

Get a pair of welder's gloves and use a blow lamp to heat the electrodes till the side electrode glows red then quickly screw it in. Try pulling the starter with no choke and throttle wide. There may be a build up of oil in the crankcase as it has drained through and the petrol has evaporated.

AJH

[Steve Firth]

"TMC" wrote: [snip]

Follow Dave Plowman's advice. If that doesn't work, try injecting a squirt of butane gas into the inlet. You can do this using an unlit blowlamp or a butane lighter or a butane lighter refill can. The butane/air mix is easier to ignite than petrol and can kick over the motor enough to cause it to run happily afterwards.

[Tabby]

There are also easy starting sprays that often work.

NT

[Ericp]

Any timing adjustment?

[robgraham]

I've never actually looked at the book for either of my chainsaws but the characteristic that I use is full choke until it fires - neither ever run on, so close the choke and usually they both will start first pull after that. And thinking about it the petrol strimmer is the same.

I have had occasions when something won't start and have given up only for it to oblige almost first pull the next day.

I like the butane idea - hadn't heard that one before. One thing that I have heard is that 2 stroke mixture deteriorates in storage though personally that's not been a problem I've experienced.

Rob

[Dave Liquorice]

As others have said two strokes can be tempremental until you get to know your particular engine. I go for prime, full choke, full throttle, pull until it gives the slighest hint of firing, half choke, pull until it tries to fire/run again keeping the throttle open. Once it does runa bit try closing the throttle but it'll probably die. If you can get a few tens of seconds running it'll then start to get warm enough to run sans choke and throttle.

I'd be a bit wary of using a starting spray (probably ether) or butane, it may work but goes with a bit more a bang than petrol and may damage rings/pistons etc.

[The Natural Philosopher]

What he says.

If you have fresh fuel and a spark it will fire. Then if the carb is anything like set up it will run until you can get the settings right.

If it wont fire its either grossly over rich or grossly over weak. Or there is no spark. Or the fuel is very stale.

If it fires a bit , runs, then dies is usually a sign of a weak mixture. reprime and choke hard on, BUT the moment it does fire get rid of (most of) the choke..

If it wont fire at all chances are its flooded. No choke and keep pulling till enough air has swept the cylinder clean.

Years of starting model aircraft engines in my youth does give me a bit of and advantage its true. Nothing is worse than a crap British FROG 80

60s diesel engine..not even the finger ripping AMCO 35...

[The Other Mike]

[Nick Leverton]

Nick

[Steve Firth]

The Natural Philosopher wrote: [snip]

My right index finger is largely scar tissue thanks to one of those.

[H. Neary]

Low compression due to a worn cylinder/ rings?

An exhaust blocked with soot.

I'm not familiar with chainsaws but my Raliegh Wisp moped used to fail to run because of the above.

I seem to recall that timing was some kind of mechanical switch hit by a lump on the outer ring of the magneto.

A squirt of Redex might help the finger, not sure about the engine though.

HN

[TMC]

Thanks for the replies

There are full starting instructions on the case but all in swedish

Got it to start by starting on full throttle

it ran then for a minute or so till the fuel pipe split at the carb

cut and reconnected fuel pipe and ran it for a while but think I need to replace the pipe

Seems to run on full throttle but dies on tick over so I guess a bit of adjustment needed as well

Regards

[News]

In message , The Natural Philosopher writes

So, you've never had a Lambretta that wouldn't start?

:-)

[Terry Fields]

Try a brand new spark plug, and make sure it has the right gap.

Do not over-choke or overflood - my two-stroke motorcycle has a 'starting jet' fed by a drilling in the carburettor. ANY opening of the throttle during kick-starting draws in even more fuel and floods the engine.

You need to sneak up on the correct balance of choke and throttle, until you understand its starting characteristics.

A new plug is essential.

HTH

TF

[The Natural Philosopher]

sound rich to me..then