Ok Cat guys....here's the situation: Cousin has a 97 ZRT 600. Suddenly, the sled started bogging real bad and isn't getting the rpms it needs. Now I think it is likely a broken primary spring, as the engagement dropped almost 1000rpms/...what do you guys think?
* * * * Any suggestions as to a good spring to replace it with? He has the yellow/green in it right now and it engaged at 5000rpm. He is convinced that his weights are shaved and notched and therefore not stock. What spring would work good here..give him a ~4500rpm engagement and a good final tension? http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/confused.gif

Has he looked to see if the spring is broken? *It could just be a bad belt too along with several other things.
I don't think that he wants his engagement to be that low either. *I have played with several different springs and once engagement gets below 5 grand, it is real weak on take off until the r's get up there. *IMO I think he would be better off with a HPE orange spring in the primary and stock secondary spring. *This will RAISE his engagement to about 5100-5200 rpm and it really helped it get out of the hole(assuming he has the stock weights in) *If his weights are in fact shaved, he could go with a lighter spring, or just put some 54A gram weights in. *Those worked will with the HPE spring and will give him a full shift out around 8200-8300rpm with secondary in the middle position.

check the motor mounts to make sure they're all Ok, especially the rear clutch side. that can cause a bog as the engine binds

PH...his engagement was about 5000 before the sled started behaving this way. He told me he had a yellow spring with green dots in there, but he hasn't checked it to see if its broken. Motor mounts should be fine.

I would say the motor mounts should be ok as well. *If he has a broken motor mount it should really loud when it has a bit of throttle, because the motor will be twisting away from the exhaust and causing it to be like open headers. *This is what happened to my 96 Zrt600.

if the spring broke you might want to chack and see if there is any play in the spring you should be able to move the spring a very little or it could be to tight,i have seen some cluth covers that neede to be machined for a particular spring i kept breaking my spring in an epi clutch kit and had to get the cover machined so there is something to think about

Well, the 1997 ZRT600 clutching wasn't that bad so I would put everything back to stock. Here's the spec's:

Drive Clutch
Cam Arm = 746-560 (55g.)
Dr. Cl. Spring = 646-229 (Yellow/White)
Engagement RPM = 4500 t0 4900
Peak eng. RPM = 8300 to 8500

Driven Clutch
Spring = 148-227 (Yellow)
Torque Bracket = 648-005 (55 deg.)
Spring Tension = Third Hole
Anyhow, thats just my .02

* *-Auggie-