Chainsaw engine rebuild

Louisd1 · 10-01-2009, 02:49 PM

I have a poulan pro 4218 avx chain saw which doesnot I idle correctly and stalls on acceleration. I took chainsaw to a dealer for repair and dealer told me that chainsaw didnot have compression. My question is what special mechanical tools and jigs are needed to rebuild engine. Any advise appreciated !

Regards
louisd1

vmaxrich · 10-13-2009, 06:29 AM

Before you start taking things apart I would confirm what the dealer said is true.To me it sounds more carburetor related than a compression issue.I always found that if you had resistance when you pulled the cord you have got compression. As far as tools for the rebuild I have never done one but I know you will need a special tool for the piston rings and some thing for the valves.
Good luck.

Vatar · 10-13-2009, 10:36 AM

I agree with vmax check your compression (you can go to a small engine shop) If you have bad compression sometimes you can have the cylinders honed and throw a set of new .02 or .03 over rings on the piston and she will come right to life. If you've never refreshed an engine it is kind of a daunting task. I would have a small engine mechanic work on it.

Hopefully its just your carburetor then its a matter of cleaning the thing or rebuilding it.

**K-B** · 10-15-2009, 06:08 PM

What you're describing could definitely be a compression issue. A quick and easy way to perform a compression check is to lift the saw off the floor by the starter handle. If it steadily drops, the compression is too low. Normally, it will drop a bit, then a marked pause, then drop a bit more.

If the compression is low, I'd probably toss the saw and get something better (Honestly, that's a pretty junky/cheap saw).

If it DOES have low compression, don't try messing with it trying to hone the cylinder, etc. For one thing, there is no such thing as an oversize ring for it. Those cylinders are unplated (bare aluminum, easily scored). You're going to need a new piston & cylinder if you want to do it right. You actually don't HAVE to have any special tools, although they do make it easier. (There are no valves, btw). A piston & cylinder set will run you around $60.

mstpops · 11-16-2009, 12:18 AM

re chainsaw rebuild -before thinking compression problems do a compression test
have a look with the muffler off @ the cylinder and bore any scores or marks ?
rings should still be spongy compression should be about off the top of my head no lower than about 115 psi approx certainly the absolute btm limit for most machines is about 100 psi spark test loaded and un loaded should jump a 6 - 8 mm gap - carburettor should be rebuilt with a new carb kit & setup barrell,bolts should be tight -muffler should be clear with no carbon build up, air filter clean , tank breather ok, fuel lines with no holes ,and fuel filter new , - be sure to pressure and vacuum test crankcase for leaks @ seals and base gasket,at manfifold block or boot , check boot for holes -

have a look cheers mstpops

10-01-2009, 02:49 PM	#1 (permalink)
Louisd1 Registered User Join Date: Oct 2009 Posts: 1 OS: xp	Chainsaw engine rebuild I have a poulan pro 4218 avx chain saw which doesnot I idle correctly and stalls on acceleration. I took chainsaw to a dealer for repair and dealer told me that chainsaw didnot have compression. My question is what special mechanical tools and jigs are needed to rebuild engine. Any advise appreciated ! Regards louisd1

10-13-2009, 06:29 AM	#2 (permalink)
vmaxrich Registered User Join Date: Oct 2009 Posts: 4 OS: xp	Re: Chainsaw engine rebuild Before you start taking things apart I would confirm what the dealer said is true.To me it sounds more carburetor related than a compression issue.I always found that if you had resistance when you pulled the cord you have got compression. As far as tools for the rebuild I have never done one but I know you will need a special tool for the piston rings and some thing for the valves. Good luck.

10-13-2009, 10:36 AM	#3 (permalink)
Vatar Registered User Join Date: Oct 2009 Posts: 26 OS: 2000 Professional	Re: Chainsaw engine rebuild I agree with vmax check your compression (you can go to a small engine shop) If you have bad compression sometimes you can have the cylinders honed and throw a set of new .02 or .03 over rings on the piston and she will come right to life. If you've never refreshed an engine it is kind of a daunting task. I would have a small engine mechanic work on it. Hopefully its just your carburetor then its a matter of cleaning the thing or rebuilding it.

10-15-2009, 06:08 PM	#4 (permalink)
K-B Moderator, Linux Join Date: Oct 2005 Location: NY Posts: 2,873 OS: Vista, Ubuntu My System	Re: Chainsaw engine rebuild What you're describing could definitely be a compression issue. A quick and easy way to perform a compression check is to lift the saw off the floor by the starter handle. If it steadily drops, the compression is too low. Normally, it will drop a bit, then a marked pause, then drop a bit more. If the compression is low, I'd probably toss the saw and get something better (Honestly, that's a pretty junky/cheap saw). If it DOES have low compression, don't try messing with it trying to hone the cylinder, etc. For one thing, there is no such thing as an oversize ring for it. Those cylinders are unplated (bare aluminum, easily scored). You're going to need a new piston & cylinder if you want to do it right. You actually don't HAVE to have any special tools, although they do make it easier. (There are no valves, btw). A piston & cylinder set will run you around $60. __________________

11-16-2009, 12:18 AM	#5 (permalink)
mstpops Registered User Join Date: Oct 2009 Posts: 18 OS: xp	Re: Chainsaw engine rebuild re chainsaw rebuild -before thinking compression problems do a compression test have a look with the muffler off @ the cylinder and bore any scores or marks ? rings should still be spongy compression should be about off the top of my head no lower than about 115 psi approx certainly the absolute btm limit for most machines is about 100 psi spark test loaded and un loaded should jump a 6 - 8 mm gap - carburettor should be rebuilt with a new carb kit & setup barrell,bolts should be tight -muffler should be clear with no carbon build up, air filter clean , tank breather ok, fuel lines with no holes ,and fuel filter new , - be sure to pressure and vacuum test crankcase for leaks @ seals and base gasket,at manfifold block or boot , check boot for holes - have a look cheers mstpops