920 jonsereds won't fire ?

[kurt]

I purchased a 920 last night for 250 bucks. It has great compression cleaned carb new lines it has spark as well thing will not fire or anything. Need advice

 

[JC360]

Try a new plug? Check gap. Make sure muff screen isnt plugged.

 

[AVB]

I purchased a 920 last night for 250 bucks. It has great compression cleaned carb new lines it has spark as well thing will not fire or anything. Need advice

Also check your flywheel timing; could have sheared key.

 

[kurt]

Checked key its just fine re set charging pickup with feeler guage . Exhaust is free flowing. My spark looks good I'm wondering if it could be the coil ?

 

[Dan_IN_MN]

If you have a timing light, you can mark TDC and check the condition of your coil.

Did you check the compression with a gauge?

 

[kurt]

I will have to do that the exhaust side of the piston does have some scaring. I don't have a compression gauge in my shop I'll check these things tomorrow. I got the saw cheap if it needs a new cylinder and ignition I won't be to heartbroken. Smart thinking on the tdc mark

 

[Thommo]

Tip some fuel in a bottle cap and pour it down the carby and then see if it fires. If it only runs for a second or two you have a carby or fuel supply problem

 

[shawn022]

Welcome to the forum Kurt. I see your from the News. How did you find that saw around here? Not common at all in these parts. I know these things fairly well, so if you need help let me know. As far as parts you may be heart broken once you start trying to find them. If your piston is scored you really should go through that saw before attempting to run it. If you ruin the cylinder by continuing to run it, it may be hard to find another. Aftermarket ignitions were available for these saws. I have a couple extra pick ups ( flywheel side of the ignition) but no extra coils.

 

[AVB]

I see that your a new forum member and I don't your experience level so I might this tip too. Most 2 cycles require a minimum compression of 100 psi to even hit so this where a good compression gauge comes in handy when diagnosing non-start problems. There are few that will start below this psi but not many that I know of.

 

[kurt]

I found the saw on Craig's list I'm planning on mounting it to a chainsaw mill setup. I have a lathe in my shop cylinder heads are hard to find I might cut and sleeve the cylinder . I'll check compression today. But my gut says spark issue are there any coils that will retro fit it

 

[kurt]

Mechanic in the navy for 4 years, I built a 1978 GS 750 motor ported polished milled and have good mechanical understanding. But I don't know everything that's why I'm posting

 

[AVB]

Mechanic in the navy for 4 years, I built a 1978 GS 750 motor ported polished milled and have good mechanical understanding. But I don't know everything that's why I'm posting

It not a problem. Personally I had worked on 4 cycle engines all my life but when it came to 2 cycle engines it was a new experience to say the least.

Glad to have you ask for help and not afraid to admit you need some help; we all do from time to time even the most experienced run into problems and need some help. Forgive us if we ask some novice level questions that you already have the answers to.

This forum is one of the best I have been a member of when it comes to 2 cycle equipment and especially chainsaws. I have put a lot of the knowledge gain through just reading the posts here to practical use in my small engine repair business.

 

[kurt]

I've only got 93 psi compression

 

[AVB]

May be simply a stuck ring; although, most times for me it always seems to be piston, ring, and sometimes even cylinder damage. With you saying you have seen some scoring on the exhaust side I would be prepared for complete cylinder, piston, and ring replacement.

Some of the guys will know if it can honed or not. I just learning that phase here. Really have not got actually doing it yet so I if it can be done or not. I just see that some flex hones are in the sizes that I would need.

 

[shawn022]

I'm going to assume you bought it as- is, as most Craigslist deals are done. You should be able to clean up the cylinder. I've used episan aftermarket pistons for the 920 with good results. I'm not sure if they are still available for the 920. Time to pressure and vacuum test the saw.

 

[SCHallenger]

I had a 920 for about 30yrs. I don't know exactly what the comp. should be, but I can tell you that I suspect it to be north of 200. At this time I have a Stihl MS261 that has had the squish tightened. It had 165 before the mod & now has 190. Compared to the 920, it is a cream puff to pull over. If I let the 920 sit for awhile, I used to pull the plug & give it a few spins before I could crank it with the plug in place, & it was bone stock!

 

[kurt]

yea the rings are melted into the piston in a 1/8 inch section of the piston the cylinder still is cross hatched hopefully it will clean up ok

 

[kurt]

got saw running today cylinder took hours to clean but good as new new vec piston. only problem i had was the saw was not run for years the pull starter lobes on the flywheel one of the clips gave out i broke 2 fins off unfortuneatly. i cut a new bolt set on my lathe lastnight starter engages fine now best chainsaw i have ever used worth all the effort of fixing.

 

[flyboy553]

I have sold a lot of saws of all kinds of makes. The 920 is the only one I truly regret selling. I really liked that saw.

Ted

 

[SCHallenger]

got saw running today cylinder took hours to clean but good as new new vec piston. only problem i had was the saw was not run for years the pull starter lobes on the flywheel one of the clips gave out i broke 2 fins off unfortuneatly. i cut a new bolt set on my lathe lastnight starter engages fine now best chainsaw i have ever used worth all the effort of fixing.

I thought it was a fantastic saw except for the filtration system. FWIW, I had much better performance out of the flocked filters than the nylon type.