Help Me ID my clutch rivets

supercharged111

supercharged111

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Sep 12, 2011
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Location
Da U.P.
My sled revs out to 8700 RPM at low speeds WOT (<80mph) as of 2012, last time I rode. I'm headed back to MI for Christmas and I plan to ride again. A closer look at my sled revealed it already had the HG mod and reed notch mod done to it, so that likely explains why. I'm assuming these rivets are stock, but would like to know for sure. Do I need to cut them out and weigh to be certain? I was planning to go up one weight on the inner weight to try to get it down in the 8300-8500 range. I will drill the muffler baffle out tomorrow for whatever that's worth, I assume not much at this point. Jetting is stock for 330-1700' and 0*F, exactly what I'd planned to jet it for so perfect there. I have no intention of jetting down now with the prevalence of E10 out there. Only other small hopeful mod is to score a 22 tooth upper gear, unless I find out my sled already has that too. I need to know where I am to know where I'll end up going as far as clutching goes. Weights appear to be the 8CH, pics of rivets below.


 
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appears to be 3.6 inner due to the dark coloring and a 4.5 in the tip.
 
I would be interested in what you do and how it works out for you. My sled has a similar over rev. Hows your belt?? Sometimes a bad belt can cause it to over rev.

here what I think I am going to try. One piece at a time. I started with a straight 47 degree helix out of an srx. There is no snow here yet so I have not had a chance to test ride.

use 8ch weights (stock) put 4.5 grams rivets in both holes, 8bv-17604-41-00 straight 47 degree helix. 2 engagement shims. set secondary spring at 60 or 70. use stock rollers, springs. Then if we still have the some over rev go to the 14.5mm roller.


My current set up except the 47 degree helix.

primary
weights 8ch 4.5 inner (17.2 rivet) outer 3.6 (13.9 rivet)
stock spring wsw
rollers stock 15mm

secodary
green spring (stock)
set at 60 degrees
stock helix 45 degree

belt is 89l with about 200 miles on it.

Engagement is about 3600. Sled turns 8700-8900 rpms at wot. would like to get that to 8300-8500

In the tech section

Under target rpm.

Too heavy primary (drive) weights.
Too steep secondary (driven) helix angle.
Too low tension in secondary (driven) clutch.
Too tall gearing.

Over target rpm.

Too light of primary (drive) weights.
Too high tension in secondary (driven) clutch.
Too shallow secondary (driven) helix angle.
Too low gearing.
 
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Thanks for the quick response guys. My secondary spring is set to the stock position, whatever that is (I forget, but remember asking the dealer where to put it). Here's the catch: I have a dual angle Bender helix on there. I tried asking them what it was and they were no help. What can you guys tell me? IIRC, it over-revved before the helix too. When I first got it with the stock helix, I remember it overrevving and then when I installed the 1.25" paddle track it stopped over-revving. I figured it was the track, but it ended up being some plugged pilot jets. Cleaned them out and the sled had lost no top end to the new track! What backshifting consequences might I suffer by letting that secondary spring out a click? I figure between that, some weights, and a couple engagement shims I can at least make it less bad. Ooh, and I do have a red secondary spring from when I started gathering parts to calibrate it for CO.
 
What belt are you using? I know I read on here some where the 8dn will produce a little higher rpm. Compaired to 89L. Due to the difference in the compound.
 
All the Yamaha belts are hard as a rock and slip a lot. Try a carslile ultimax 805-XS. That may help some of your rpm problems right there.
 
They make 2 rivets they call 17.2mm one has a hole in it I believe. So the weight of it is still 3.6g same as 13.9. I am wondering are you rivets the same length? Does one have a hole in it. I am only going off this chart below. I know you said you have a bender helix. Anything else look like its not stock??

in tech pages here is what stock set-up would be for a 98 sx700
primary
weights 8ch with 13.9 (3.6g) rivets both holes. 14.5mm rollers, spring wsw

Secondary
45 degree straight helix 60 degrees green spring, belt 8dn, gearing 23/40

View attachment 56355
 
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Both of my belts are 8DN. Next I'll measure the length of my rivets and verify my gearing. Rollers are 14.5mm in diameter.
 
Might be a good idea to give the clutch a thorough cleaning in the dishwasher or solvent tank, yours isn't the dirtiest clutch out there but not the cleanest either. Spend some extra time to get the tower channels cleaned out where the plastic sliders ride. Also inspect of all bushings and plastic sliders, making sure everything is free to move/spin/rotate, but not too loose or sloppy. After doing this along with verifying all of the tuning components that are in the clutch, you may want to reinstall and run it for another baseline, especially if you had to replace any wear parts.

Another way to help with tuning and to ID the rivets is to pick up an accurate gram scale if you don't already have one, then remove one or all of the weights and compare what you get on the scale with Yamaha's specs for the weight itself plus the installed rivet weights. If you're going to make modifications to the sled over time, it's a good idea to log all this information for an ongoing and future reference.
 
I don't have a clutch removal tool, though I had considered hot tanking it to get all the gunk off. I'm thinking of getting a new high engagement primary spring, cleaning the clutch faces, and going from there. If that works, then Turk's setup would probably work good too. 4.5 inner, 3.1 outer, 22 tooth top gear.
 
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