Out Of Phase Crank

4245 Views 2 Replies 3 Participants Last post by 94ZR580, Mar 2, 2007

fast426

Discussion Starter · Mar 2, 2007

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.

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63November

· #2 · Mar 2, 2007

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?

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94ZR580

· #3 · Mar 2, 2007

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.

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