Bent Crank???

[kodiakfisher]

I have an old Mac 4900 and I recently purchased new chains. When I put the new chain on the old sprocket the chain binds and will not spin freely given proper chain tightening.

No problem I thought...I had a new sprocket due to wear (uneven) on the old one so I thought new chains and new sprocket should do the trick. The chains still binds but not as bad.

I get a slight audible click when pulling the chain around the bar. Just before the click the small amount of slack in the chain gets really tight and then click the chain keeps moving. By looking at the old sprocket there is evidence of uneven wear and I remember having trouble with chains early on with this saw but wear on the sprocket seems to have taken care of this with old chains the problem is back with new chains and old or new sprocket.

What do the experts think. BTW the saw runs great.

Kodiakfisher

 

[Fish]

If it was a bent crank, the binding and stretching would equalize in short order, and
you would have horrid vibration as the weight of the clutch would make any bend
quite apparrent[sp]. Your problem may/may not be in a slight variation in the pitch, if
it is the 3/8s chain. You might want to do a search of past posts regarding 3/8
vs. .375 pitch chains. I can't really tell you much more than that, as I do not read those threads that contain alot of bullpoop, and I never have had any real
problems arise in my Small Saw region that would involve this. I may even be way
off on this, as I did not read those threads, but you may look at them.
Sorry my response was not more helpful, but you may look at those threads, it
may help you.