-Knock knock! -Who's there? Yep, you know it! MS650

[popopboat]

Just bought a ms650 for 70$ in working condition, has an excellent compression (even with a leaky decomp valve) , but guy said that it has a knocking sound... immidiately knew whats the problem.
Only a crankcase is aftermarket, everything else is OEM, even the knocking crankshaft.
Cylinder is in flawless condition, still some hatchmarks left.

I always wanted to try to rebuilt a crankshaft, replace conrod and crankpin, so i got a chance!
Has anyone done that here? How much force needed to separate it?


Check this out what i found while dissasesmbling, ive heard that this increases torque by 47%

 

[Wonkydonkey]

I'm sure someone will be along to say you need a jig and 10ton press.

 

[popopboat]

I'm sure someone will be along to say you need a jig and 10ton press.

Yes yes
Im aware of that, im planning to do it on real hydraulic press anyways, but i like to hear what else people did.

 

[bigbadbob]

Where would you get the parts??

 

[popopboat]

Where would you get the parts??

Good question indeed.
Aftermarket touched my mind, but thats the last option.
I have a 064 crankshaft with broken flywheel thread part, so i could perhaps sacrifice it? Bearing is literally like new.

Nvm just realized that 064 has smaller diameter

 

[deye223]

And here's me thinking that the 650 was just a 660 with a 80 odd cc top end on it

 

[popopboat]

And here's me thinking that the 650 was just a 660 with a 80 odd cc top end on it

Yep exactly the same saws, just different top end so less stress on the crankshaft....hmmm

 

[popopboat]

What do you people think about afermarket cranks?
Im not a heavy user and always run 40:1 or richer.

Or, what is an okay price for an used 660 crank?

 

[BuckthornBonnie]

I wouldn’t use an AM crank in a work environment. I don’t recommend them and feel like they’re just for the hobby guy who has many other saws to use when/if it goes down.
Used oem varies so much... but maybe $40-$80?

 

[Stump Shot]

I wouldn’t use an AM crank in a work environment. I don’t recommend them and feel like they’re just for the hobby guy who has many other saws to use when/if it goes down.
Used oem varies so much... but maybe $40-$80?

/\
This

 

[popopboat]

I wouldn’t use an AM crank in a work environment. I don’t recommend them and feel like they’re just for the hobby guy who has many other saws to use when/if it goes down.
Used oem varies so much... but maybe $40-$80?

Well, same thoughts.
I am in the end a hobby guy, but i couldnt live with a feeling that it may go awol every moment...
I found a crankshaft+piston (ms660, but guy wont sell it separately) for 60$, but cant see it in person...
It kinda feels strange to buy a 60$ part for a 70$ saw lol, but i suppose its worth it as the rest of it is in literally top condition.

 

[BuckthornBonnie]

It’s definitely worth it.

 

[CR888]

What you pay for something and what it's worth can be sometimes completely different. If the used piston and crank are good, $60 is absolutely definitely worth every cent. Buy it! Think of the end goal of having a good saw built with good parts. That will be worth more than $130.

 

[Stump Shot]

Well, same thoughts.
I am in the end a hobby guy, but i couldnt live with a feeling that it may go awol every moment...
I found a crankshaft+piston (ms660, but guy wont sell it separately) for 60$, but cant see it in person...
It kinda feels strange to buy a 60$ part for a 70$ saw lol, but i suppose its worth it as the rest of it is in literally top condition.

If you fix it right, it won't be a $70 saw no more.

 

[popopboat]

Well thats the encouragement i needed lol.

.

 

[popopboat]

Doesnt look too bad even this way.

 

[popopboat]

Okay, crankshaft has arrived.
Looks really nice in first sight, looks and feels brand new.
BUT, why is there a " N " on crankrod, i thought that stihl crankshafts have " S " like on the bad one and on the 064 crank.
Anyone with more experience can confirm is this oem or? someone fidgeted with crankrod?

 

[kingOFgEEEks]

That one is for the Northern hemisphere. The S ones are for south of the equator!

(FYI, just kidding, I don't know why it has an N instead of an S)

 

[popopboat]

That one is for the Northern hemisphere. The S ones are for south of the equator!

(FYI, just kidding, I don't know why it has an N instead of an S)

Aahh, thats why last one died, was made for south heh.


I found a OEM crank (atleast guy who is selling them on ebay states that) with a letter " T " on crankrod, maybe generation of manufacturing, or manufacturer signature?

Also markings on a crankshaft are different, this is from an old crank.

 

[ManiacalMark]

I would imagine the letters have to do with the time they were made.