1st MS660 failure

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fleethirte

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Hello all, my first kit build has failed. Take a look at my tear down! I was hoping for a easy jug replace but I don’t think that is the case!
 

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Hello all, my first kit build has failed. Take a look at my tear down! I was hoping for a easy jug replace but I don’t think that is the case!
I will be rebuilding a Stihl soon and have never done so before. I would like to learn as much as I can from others, even the failures, before I start. What am I looking at that is not normal in your pictures? I would hope you could take a few minutes and point them out.
Thanks
 
I will be rebuilding a Stihl soon and have never done so before. I would like to learn as much as I can from others, even the failures, before I start. What am I looking at that is not normal in your pictures? I would hope you could take a few minutes and point them out.
Thanks
 

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Somewhere on another site I'd swear I heard a few guys say Raisman-Platt cranks were da bomb for a/m 660 cranks. I'm not sure why I was reading a thread on a/m 660 cranks since I don't own a 660, but that's what I recall reading.
I saw that too, but then someone else said they are made by Farmertech and just repackaged
 
So I ordered a Farmertech and a Raisman.
around 30 dollars more for the Raisman.
When I got the Raisman in the mail and pulled it out I thought I was getting a repackaged marked up Farmertech. But if you look at the pictures there is a difference.
farmertech is the darker one.
Raisman has obvious more machining done to it. Could just be a machined Farmertech but it is a better product. Seems to move smoother as well. Which could just be do to more evidence of oil on it.
 

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So new crank has been installed.
After case screws were tightened there was drag on the crank. Used feeler gauges and the hammer technique as advised to center the crank and obviously drag on the crank was gone, it rolled smooth. However, snugged up case screws again for conscience sake. Now there was drag on crank again..... tapped her a little bit and re centered.... all good again.

However if tightening case screws moved the crank , how on earth will crank stay centered while putting flywheel and clutch on.
Also how will it stay centered while you have a bar chain on her tuning 13,000 RPMs.....
 
So new crank has been installed.
After case screws were tightened there was drag on the crank. Used feeler gauges and the hammer technique as advised to center the crank and obviously drag on the crank was gone, it rolled smooth. However, snugged up case screws again for conscience sake. Now there was drag on crank again..... tapped her a little bit and re centered.... all good again.

However if tightening case screws moved the crank , how on earth will crank stay centered while putting flywheel and clutch on.
Also how will it stay centered while you have a bar chain on her tuning 13,000 RPMs.....
Tightening case screws puts sideways pressure on the crank bearings & in turn the crank. Clutch, flywheel, etc only put pressure on the crank where they're attached to it (outside the bearings, seals, etc) & only put rotational forces on it when in use (under normal operating conditions)
Edit: Crank would only "float" if there was a loose fit between crank & bearings or bearings & housings. Bearing retaining compound will usually address that if it's not too excessive
 
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