opsled
Active member
SRXfromHELL said:
102 is 7.5 in, 108 is 8".
The original Yamaha/Comet 102-C that came with those sleds in 83 had a Red/blue (Yamaha) spring, A-3 weights and no shims. In 84 they updated to a white/yellow spring with everything else staying the same. A pink spring in C-2 at 40* twist was standard. With that setup engagement should be at 4000 to 4200 shifting should be at 8200 to 8400.
The 108 Comet replacement clutch had A-3 weights and a silver (Comet) spring. A lot of people (most) have had major problems getting the 108 to work as well as the 102 it came with. There are many theories as to why but I think the biggest is the difference in diameter. I have had about 8 different Vmax 540's through here in the last 5 years or so and everyone of the that was running a 108 had a belt "burn" mark at the top 1/2" of the primary. The sleds that I actually rode would not acheve the RPM they should run at. My theory is that the stock secondary that was designed to run with a 102 won't open far enough to allow the belt to reach the top in the 108 when it is fully closed. At that point the belt is being streached which is robbing serious HP and leaving the burn mark at the top (1/2") of the 108. We fixed that problem on a 78 SRX with a 540 install by removing some material from the back side of the secondary helix (where the snap ring goes) which allowed it to open far enough so the belt could get to the top of the primary without binding or streatching. That sled would yank your arms off until about 70mph at 7500 then just lay down and slowly gain rpms and had the burn mark at the top of the primary. After the secondary fix it was a completely different animal. It runs right to 9000 (it has mods) and flat hauls the mail. No more belt burn and it doesn't quit pulling. That 1 issue turned a turd into a rocket.
Tyler, if you are running a 102 you won't have those issues. I don't know what a purple spring will do for you but you need to post what weights you are running for anyone to be able to give much advice on your setup. I will say that your engine should run without any low end bog with the stock pilots and slides if you have everything set right and are running an air box. When you did the swap into your 81 did you use the Vmax throttle block? If not your carbs might not be opening all the way. The 81 butterfly carbs had a throttle pull of about 3/4" from idle to WOT and the 38mm slides from the Vmax have a throttle pull of about 1 3/8". It you are running the 81 throttle block on 38mm slide carbs it won't pull them all the way open.
Check all this stuff out and post your weights.
Good Luck, opsled
tyler440
Member
yes phil i already ran into that problem with the throttle block and i switched it to vmax... the slides are going up all the way... checked that lastnight.... i have the airbox there still.... ill have to take the clutch apart and see what weights are in i guess.... i cant imagine they would be anything but stock but who know what the last guy did