how much rivet weight to lower the rpm's by 300 and where?

[Yama49601]

A friend is trying to get his clutch dialed in. He's using this setup on a 97 XTC 600:

"8ab weights; 50/44 helix, green secondary spring at 60 wrap. Clutch it to run at 7800 rpm. I think if I remember that far back 2.4 gram rivets in both holes was close."

He needs to lower the rpms by 300 because it's running at 8100. Does anyone know how much weight he needs to add? And should he just add it to the tip? I've read 1 gram between the 3 weights will lower it around 100 rpm's so does that mean he should add around 1 gram to each tip rivet to get it down?

 

[Turk]

Change both rivets to 3.1 or try a new belt.

 

[Yama49601]

Thanks. I was hoping you would answer

 

[daman]

got the same set up in my '98 xtc( all stock) put a 3.1 in(i think) just the tip and sh'e 78-7,900 real close..

 

[Yama49601]

Hey Turk, we installed the 3.1's and it's still over revving. He claims it's still at 8100 and that the 3.1's barely changed it. Should we just keep going up in weight with the rivets and change both again? I'm not sure what the deal is but this thing has that .6mm head gasket and the motor just had new pistons and rings put in it. The gears are stock (23/39). The deflection is set right. The clutches are aligned. The belt is almost new. Thanks for the help.

 

[Yama49601]

I just thought of something else too. Do you think maybe he has the wrong rollers in this thing?

 

[Yama49601]

Well I just went and looked at the rollers and they're right (I think, they're stock 15.6mm is what's in it). Is that what's supposed to be used with this setup Turk? Thanks.

 

[Turk]

Just keep adding weight till you get the desired rpm,s. Tuning in a set up is usually trial & error & can take a few attempts....especially if i am trying to do this from 1000 miles away & not able to see & ride a 10 year old sled that might have some other issues.

 

[Yama49601]

Thank you.

 

[Yama49601]

Well we have 4.5 gram rivets in both holes now and it's still over revving (according to him). What else could be screwed up to be causing this? He wants to have his tach checked now. Do you think it's likely that the tach could be off that far? How could this thing possibly have that much power to need more weight than that? Oh I forgot too he said it's acting funny now since I put the 4.5's in all the weights. I'm not sure exactly what he means by that but I have a feeling it's too much weight in the primary?

 

[Turk]

Is he using a tall cover primary spring in the short cover primary clutch? adding more weight has gotta lower rpm,s unless he has an issue with a bad bushing or 2 in the primary. check rollers & weights for any side to side or up & down play. U got something not normal going on.