Snowmobile World banner

Out Of Phase Crank

4245 Views 2 Replies 3 Participants Last post by  94ZR580
Well I have been having problems with my T-cat (96 with a 992) not wanting to run past 8300. I did everything to the clutches, messed with it tons. I kept taking weight out and adding more spring pressure and all I got was a hot clutch.

I had a clutch let loose on me at the beginning of the season while cooking across the lake.

I decided to check the crank. I am pretty confident these numbers are right (I check it three times)

On a degree wheel, here are the TDC:

PTO - 4.5 degrees
Ctr - 245 degrees
Mag - 125 degrees

SO it looks like the PTO cylinder is 1/2 degree out of whack.

First question, is this most likely my RPM problem? Is this enough to make that much difference (I used to be able to pull 8800-9000, no problem)

I am assuming that there is no tolerance and this should be perfect correct?

It looks like it is time to get it trued/welded. This sucks because I really don;t know that I can get it apart/sent out and back together before the ice melts.
1 - 3 of 3 Posts
I'm not sure that I would consider that to be the likely problem. I'm not sure, either, how you're getting those numbers as none are actually TDC (top dead center) anyway, are they?

A slight change in timing - there a half degree overall would have a much larger effect, wear in the cylinders or pistons/rings, or carburetor wear could have the detrimental effect on the rpm/ power you're seeing. Any source of friction or added rotational load in the system could be the problem also: studs, track tension, worn track clips, a different, especially heavier track, track alignment, as well as clutch or even chaincase alignment variances.

What are the changes in the machine since it ran at the stated goal rpms?
Did you check the clutch for damage? I would think that the half a degree out on the one cylinder wouldn't cause the loss of RPM's, but if it is far enough out you would loose that piston to detonation. I had a crank, twin cylinder, that was 4 deg out of phase and it put a nice big crater in the centre of the piston. Take a closer look at the clutch.
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.