ms440 Rebuild

[Carolina Diesel]

can you explain which bolts you are saying I should loosen? I had someone try to start it this evening and they advised that the ignition timing is off and the piston is in the wrong spot when it tries to start and thats why the pullcord nearly rips my arm off and the saw doesn't start. he also described what i believed you guys have mentioned as setting the squish. If you can tell me which bolts you are referring to, i will get on this. thanks for the help.

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.

 

[Carolina Diesel]

pulled compression, this time with the decomp valve in the correct position and it is pulling 135. still lower than what i was expecting. however, the saw does pop like it wants to start, but i think the ignition timing is off.

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 ?

 

[NSMaple1]

can you explain which bolts you are saying I should loosen? I had someone try to start it this evening and they advised that the ignition timing is off and the piston is in the wrong spot when it tries to start and thats why the pullcord nearly rips my arm off and the saw doesn't start. he also described what i believed you guys have mentioned as setting the squish. If you can tell me which bolts you are referring to, i will get on this. thanks for the help.

That would be the bolts that hold the coil on, I believe.

But that wouldn't affect the timing - I think the only way the timing could get out is if the flywheel key is sheared or gone & the flywheel shifted on the shaft.

 

[little possum]

2-3 bolts holding the coil on. Loosen them and insert a business card in between the flywheel and coil. Retighten the bolts. Squish is clearance in between top of the piston and combustion chamber usually checked with electrical soft solder and a dab of. Grease. Same effect of reckon heads on automobile engine gotta have right clearance. But usually stock isn't off to far but there are exceptions

 

[Moparmyway]

pulled compression, this time with the decomp valve in the correct position and it is pulling 135. still lower than what i was expecting. however, the saw does pop like it wants to start, but i think the ignition timing is off.

135 is fine.
Pull off everything so you can get to the flywheel, then use an impact gun to pull the nut and washer off. Squirt in some penetrating fluid between the flywheel and the shaft, and down in the keyway. Wait about 10-15 minutes. Take a 2# hammer and on the top of the flywheel fin that lines up with the keyway, give a good shot. Maybe 2, but it should "pop" off the flywheel. Sometimes I do the opposite fin as well as use more penetrating fluid for the really stubborn ones.

A great penetrating fluid to use on your chainsaw is your mix gas .............. should be convenient.

Look at the keyway, shaft, and flywheel ............. let us know what you see, possibly take some pictures to show us ??

 

[NSMaple1]

135 is fine.
Pull off everything so you can get to the flywheel, then use an impact gun to pull the nut and washer off. Squirt in some penetrating fluid between the flywheel and the shaft, and down in the keyway. Wait about 10-15 minutes. Take a 2# hammer and on the top of the flywheel fin that lines up with the keyway, give a good shot. Maybe 2, but it should "pop" off the flywheel. Sometimes I do the opposite fin as well as use more penetrating fluid for the really stubborn ones.

A great penetrating fluid to use on your chainsaw is your mix gas .............. should be convenient.

Look at the keyway, shaft, and flywheel ............. let us know what you see, possibly take some pictures to show us ??

I think he's had the flywheel off already so shouldn't have to go through all that to get it off again.

 

[Carolina Diesel]

Please see the pictures below. everything looked normal from what i can tell.

also, to reinterate what the saw is doing: with the choke fully open i am able to pull cord fine. when i switch the choke to run, most of the time the saw will sound like it wants to fire, when this happens, about 1/3-1/2 way through pulling the cord, the cord pulls against me with great force and the decompression valve pops out.View attachment 304950View attachment 304951View attachment 304952View attachment 304953View attachment 304954

135 is fine.
Pull off everything so you can get to the flywheel, then use an impact gun to pull the nut and washer off. Squirt in some penetrating fluid between the flywheel and the shaft, and down in the keyway. Wait about 10-15 minutes. Take a 2# hammer and on the top of the flywheel fin that lines up with the keyway, give a good shot. Maybe 2, but it should "pop" off the flywheel. Sometimes I do the opposite fin as well as use more penetrating fluid for the really stubborn ones.

A great penetrating fluid to use on your chainsaw is your mix gas .............. should be convenient.

Look at the keyway, shaft, and flywheel ............. let us know what you see, possibly take some pictures to show us ??

 

[Carolina Diesel]

more pics

View attachment 304955View attachment 304956View attachment 304957View attachment 304958View attachment 304959

 

[NSMaple1]

'choke fully open' = run.

'choke fully closed' = start (button all the way down).

This is likely not the recommended thing to do, but it's worked for me a few times - sometimes a little squirt of gas into the carb intake will get things going, if all else is well. Seemed to take that little extra fuel boost to get the motor to start & run long enough to get fuel pumping all the way from the tank through the carb like it's supposed to. You can also flood it out pretty easy doing that too though.

(I'm watching this thread becuase I have an 044 to rebuild here whenever I get around to it...)

 

[stihl for life]

i think your coil its hitting the fly wheel making it stop so fast .. losses up you coil bolts , bring the mag-no side to the coil. stick a business card in between them and push the coil right tight on the business card then hold it there while tightening the coil bolts back up . this will set your gap

 

[Carolina Diesel]

I wish it was that simple. Unfortunately, a business cards fits perfectly between the two, and there is no damage on the flywheel nor coil from them coming into contact with great force. I am stumped!

i think your coil its hitting the fly wheel making it stop so fast .. losses up you coil bolts , bring the mag-no side to the coil. stick a business card in between them and push the coil right tight on the business card then hold it there while tightening the coil bolts back up . this will set your gap

 

[Mike from Maine]

You said the control lever won't stay in the 3rd position... Have you tried starting it with the lever in the 2nd position while holding the throttle? (After you get it to 'pop' in the fourth position)

Did you use an oem fuel line?

 

[Carolina Diesel]

are you suggesting the lever issue and the abrupt stop when the decompression valve is related?.......everything is oem, besides my air filter.

You said the control lever won't stay in the 3rd position... Have you tried starting it with the lever in the 2nd position while holding the throttle? (After you get it to 'pop' in the third position)

Did you use an oem fuel line?

 

[Mike from Maine]

At least on my saws if I can't get the lever to stay in 3rd --high idle-- they won't start. They will almost start and do kind what you are describing.

If a stihl won't stay in high idle I set the brake, put it on run --2nd-- and hold the throttle down while pulling the starter. (after getting it to pop in the fourth position)

 

[Carolina Diesel]

wow, you are the man. using your method, i was able to get the saw started. however, the saw will only run with my finger on the throttle and when i let go it dies. it doesnt sound very good or powerful. also, the muffler is getting VERY hot VERY quickly and I have white smoke. thoughts?

Also, any thought on fixing the throttle lever?

At least on my saws if I can't get the lever to stay in 3rd --high idle-- they won't start. They will almost start and do kind what you are describing.

If a stihl won't stay in high idle I set the brake, put it on run --2nd-- and hold the throttle down while pulling the starter. (after getting it to pop in the fourth position)

 

[treeslayer2003]

white smoke? sounds like a 4200 I worked on. it was sucking oil from the oiler past the crank seal. idk if a stihl can do that or not, jus a thought.

 

[stihl for life]

if it just dieing turn up the idle speed on the side of the saw .on the clutch right buy the air filter theirs 3 holes{just like a girl:hmm3grin2orange::hmm3grin2orange:} 2 on side by side and one under it . take a small flat head screw driver stick it in the bottem hole and turn it to the right till it will idle . {ps keep saw started and finger on the trigger just enough so it dosent die let it off just a bit to see if it will idle if not keep turning her up more ]

 

[Moparmyway]

wow, you are the man. using your method, i was able to get the saw started. however, the saw will only run with my finger on the throttle and when i let go it dies. it doesnt sound very good or powerful. also, the muffler is getting VERY hot VERY quickly and I have white smoke. thoughts?

Also, any thought on fixing the throttle lever?

Did you tune the carb ?
This is the first time it has been heated up since its put back together, how long did you run it ?

 

[Mike from Maine]

Congrats, glad you got it running. I had a feeling it was something simple.... Replacing the throttle trigger should get it to stay in high idle if nothing else is broken.

Make sure you don't leave the break on after you start it.


Turn the LA screw in a few turns and maybe the low out an 1/8 or so. Once you get the saw to idle, read up on tuning...

 

[Carolina Diesel]

I'm an idiot, the brake was on. here is a video of my first rebuilt saw running. Just need to fix the lever and i will be in business.

ms 440 rebuild - YouTube