ms440 Rebuild

[Andrew Wellman]

this is a good video from the chainsaw guy

I pulled the oil seal on the clutch side and I am pretty sure the resistance I was feeling was just from the great compression I now have. I pulled the spark plug and it turned easier. Hopefully, the new oil seal will arrive tomorrow and I can get the saw started this weekend. I want to run vacuum and compression first. Any advice on how to do this? Thanks.

The chainsaw guy shop talk Stihl 032 chainsaw pressure, vacuum testing 10 20 - YouTube

 

[kr5258]

Torquing the flywheel and clutch: stop the piston with the rope trick or plastic stop. Torquing to spec is a good thing!

 

[Carolina Diesel]

I wanted to thank everyone for the detailed info on torque and vacuum testing. several of you gave very detailed answers and that will go a long way in helping me. I had read the torque specifications in the manual (just so you guys know I'm putting in work too).

My oil seal arrived today and all I have to do is install it, fuel and perform my tests. This saw should be running by Monday. Now, I'm off to the coast for a tuna and mackeral fishing trip! Talk to you all Sunday.

 

[Trx250r180]

At 16 and my first car was a 74 Mecurey marquis and that was 1986. Maybe Randy is 25 and likes vintage chrysler products?

good thing gas was 80 cents for regular leaded when we started driving

 

[nmurph]

I pulled the oil seal on the clutch side and I am pretty sure the resistance I was feeling was just from the great compression I now have...

I missed the part about the fact that we were talking about a saw with the top end reinstalled:bang:

 

[Carolina Diesel]

I'm trying to put the sprocket back on, however I can't get the e-clip in the groove because the needle cage is sticking out too far

 

[Carolina Diesel]

not sure if that matters though, I am pulling 115 in compression. pretty frustrating. I nicked the top of the piston with the spark plug when I was trying to stop it in order to tighten clutch. ready to pull my hair out if thats why I am pulling 115.

 

[Moparmyway]

not sure if that matters though, I am pulling 115 in compression. pretty frustrating. I nicked the top of the piston with the spark plug when I was trying to stop it in order to tighten clutch. ready to pull my hair out if thats why I am pulling 115.

That seems a little low, however compression will go up as you put some time on the saw as the rings break in. Make sure to run 32:1 FULL SYNTHETIC, and re-tune that carb as soon as she runs.

Rope man - use rope in the cylinder to stop it from turning - its real soft on pistons ! Just jam some down the plug hole with the piston lowered in the cylinder, then roll the crank (in the direction you will be tightening the nut or clutch) with your hand untill she stops, then tighten away.

If its just a small little nick, you should be fine. I would remove the cylinder to make sure you didnt crack a ring, then look the nick over real carefully and polish away any sharp corners, round out anything your fingernail catches to stop unwanted detonation.

 

[Carolina Diesel]

Hello, all. I finally have some time to begin working on this saw again and wanted to update everyone as to what was going on. I reassembled the saw and tried to start it, even though I am still pulling low compression. The pull cord pulls with relative ease and every few pulls I get major resistance and the decompression valve pops out. Also, every few pulls the saw sounds like it gets spark and wants to start, however the saw jerks semi-violent and does not start. I have pulled the muffler off several times after these episodes, however it appears to be in good condition, just as when I installed it.

 

[Dan Forsh]

Assuming that you got the flywheel back on correctly located on the key, check the gap between the ignition unit and the flywheel magnets, usually just set it with a business card.

 

[Moparmyway]

Hello, all. I finally have some time to begin working on this saw again and wanted to update everyone as to what was going on. I reassembled the saw and tried to start it, even though I am still pulling low compression. The pull cord pulls with relative ease and every few pulls I get major resistance and the decompression valve pops out. Also, every few pulls the saw sounds like it gets spark and wants to start, however the saw jerks semi-violent and does not start. I have pulled the muffler off several times after these episodes, however it appears to be in good condition, just as when I installed it.

Referring back to post #147 - are you using the same spark plug ?
Have you installed a gapped new plug ?

When you are measuring compression, its with the decomp popped out correct ?

 

[little possum]

Wondering if the squish(clearance between top of the piston and combustion chamber) and maybe the base gasket having your timing off. Correct flywheel and çoil?

 

[Mike from Maine]

Did you reset the carb screws? And after it pops are you putting the lever (and is it staying) in the high idle -3rd- position?

 

[Carolina Diesel]

Did you reset the carb screws? And after it pops are you putting the lever (and is it staying) in the high idle -3rd- position?

yes, carb screws were reset. the lever is NOT staying in the third position

 

[Carolina Diesel]

Wondering if the squish(clearance between top of the piston and combustion chamber) and maybe the base gasket having your timing off. Correct flywheel and çoil?

flywheel s definitely correct (bought 2 before I wised up and bought the correct one). I have no clue on the squish or how to verify. this is the first ive heard of squish

 

[Carolina Diesel]

Referring back to post #147 - are you using the same spark plug ?
Have you installed a gapped new plug ?

When you are measuring compression, its with the decomp popped out correct ?

brand new sparkplug.

no, when i have been pulling compression, it is with the valve in all the way.

the only time the decompression has popped out is when the saw briefly sounds like its going to fire, before violently stopping (actually hurts my hand/arm it comes to such an abrupt stop

 

[Carolina Diesel]

Assuming that you got the flywheel back on correctly located on the key, check the gap between the ignition unit and the flywheel magnets, usually just set it with a business card.

i'll have to investigate how to do this in more detail as this is the first ive heard of it.

 

[Dan Forsh]

Very simple to gap.

With the flywheel magnets away from the ignition unit, loosen the bolts on the unit and insert a business card between it and the flywheel.

Now turn the flywheel around until the magnets are opposite the unit, they will grab it and try to pull it to them, but your card roughly sets the correct distance.

Tighten the bolts down and remove the card.

Finally turn the flywheel by hand a few times just to check that it's not going to foul on the unit and you should be good to go.

If you're still having the same problem you will at least know this isn't the cause.

 

[Mike from Maine]

yes, carb screws were reset. the lever is NOT staying in the third position

If the saw won't stay in the third position after it pops you'll have a hard time starting it cold.

My 066 did the same as you describe when I first got it. The trigger is worn enough so it wouldn't stay in high idle. To get it to started I pulled it till it pop'd with the choke, moved the lever to run, and set the brake. Rested the tip of the bar on a log and held the throttle all the way with my right hand while I pulled the starter with my left. Not the safest starting method but it may get your saw running.

 

[Moparmyway]

brand new sparkplug.

no, when i have been pulling compression, it is with the valve in all the way.

the only time the decompression has popped out is when the saw briefly sounds like its going to fire, before violently stopping (actually hurts my hand/arm it comes to such an abrupt stop

Thant why your getting such a low reading.
Maybe you should wash down the P&C with some mixed 2 cycle gas through the spark plug, pull her over several times with the plug still out, then re-install plug and try to start her WOT, full choke decomp in.
After a kick or pop, hold full throttle and NO choke and pull untill she starts.

The decomp is functions by allowing compression to bypass the cylinder, and out of it, untill it fires. When it fires, the resultant pressure wave closes the decomp so it runs normal.

Its normal for a rebuilt saw to run a little rough and smokey for the first few minutes while its getting warmed for the carb to be tuned correctly. 2 cycles can be finnekey, but once you unlock their starting secret, youre home free.