The question I have is I've recently torn into a ms021 and found to be a little low on compression and the bearings for the connecting rod are toast..I have a donor ms025 that has a good crank assembly the piston itself was shot so I swapped and mounted the 021 piston hardware onto it now I notice the head room has changed at the top of my stroke. piston hits the top of the cylinder my question is would it be as easy as going to the machine shop to have them take a little more material of the top of the cylinder to make up for the head room change? hoping one of these stihl guys can chime in thanks
Ms021/ms025
- Thread starter Kennyman
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I would just get a 025 piston/rings and turn the saw into an 025.
I'm leaning towards that but I kinda wanna use the mahle cylinder I have it's perfect the reason for splitting was it was getting a little on the low side of comp(115psi) then realized I had a bad bearing in the connecting rod.when I tried to find a crank assembly I can only find ms250 cranks I know these saws aren't worth a whole lot and could easily upgrade to the 250 but curiosity gets the best of me. Have you ever tried to modify the deck seems like a guy could gain a little more comp basically changing the squish on these little clams? Kinda new to this
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I am sure one of these guys has tried something like that.
Nawww....LOL
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I think that they have tried a Chevy piston at least once....
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Bolted on a Quadrajet.....
Wasn't thinking it was gonna be the best thing ever I jus think it'd funny as h*** to pull out a lil saw and take off on a bigger one I know a few of my buddies that would look at me like I was nuts pulling out the 021
Anything can be done with enough time, labor and money. What is the difference in stroke between the two cranks, first thing you need to know?
I figure I'm gonna take some measurements from the 2 connecting rods see what the diff in length is I'd like to take squish readings to get it to the .020 reading but the bearing is toast on the 021 rod shoots that out jus means I gotta take some more measurements to get it how I want it hopefully only one run thru the machine shop
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Brad could tell you about bending that rod.....
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He is the resident "expert" here on that topic.....
If you need to take metal out of the squish band then the port timing would need to be readjusted, the safe route would be to raise the ports the same amount of height removed from the head. Use a timing degree wheel ,then a bit of variation can be used to get a better balanced set of port timing numbers in place. Maybe not worth it in performance but not all projects end in disaster, experimentation is what got us to this point/level.
