I need some help with a low-end hesitation or bog when I crack the throttle. The clutches are over heating when I hill climbing. The sled is a 2002 Viper. This is list of mods that have been done to this sled. 2000 MM skid frame w/141” 2” track, 8 tooth drivers, 3-1” holes drilled in every pitch of the track and 22-38 gearing. Engine spec’s. 2 layers of head gasket removed, reed spacers, Wolfe Pack reeds, SLP triple pipe, Holtzman ATACC, 162.5 mains, 47.5 pilots, needles 3 ½ and air screw 1 7/8 turns. Clutch setup for 8000’. Yamaha primary 8DN10 w/10.3 rivet in outer hole, Green white Green spring, 2 shims and 14.5 rollers. Secondary, 43 degree helix. I have tried Maxx Roller Secondary w/green spring, 80 degrees and a 48/40 helix. The stock Yamaha Secondary with the above spec’s works better. I have also tried SLP clutch setup for the roller secondary 13.3 rivets in the inner. The engine is spinning around 9100 RPM’s, it drops below 9000 when I put the Yamaha secondary on it. I am also running a Yamaha 8DN belt. A couple of other items I would like to get an answer on. I can’t keep the motor aligned is there a torque rod for this sled? I also ride in the 1600’-2000’ level so I would like to get a setup for that elevation also. The sled pulls well once I get rolling and then peters out I think from belts slippage. I forgot to mention 120-125 PSI across all cyl’s nice tan plugs and great piston wash. How can get rid of the bog and clutch heating?
Viper Clutch Heating (Turk)
- Thread starter MM700
- Start date
The bog is probably from running too small pilots at elevation. Your mains are way too rich for 6000' too. Try running a 47 helix with a silver spring or maybe even a silver with the other helix,s. The SLP pipes here seem to work better at around 8800 rpm.
Bogging
I would also change the gearing if you want to cool off the clutches. I would go to the stock MTN Viper gearing, 21-40. Belt life will also increase, heat kills a belt. I would also try turning out your gas screws half a turn if you don't want to buy new pilot jets. Half a turn makes a lot of difference. A roller clutch also helps with belt life and running cooler clutches. However, I have found that a 48/40 helix does not work very well in the mountains. I would think that you need a helix along the lines of 41/35 with the green spring.
I would also change the gearing if you want to cool off the clutches. I would go to the stock MTN Viper gearing, 21-40. Belt life will also increase, heat kills a belt. I would also try turning out your gas screws half a turn if you don't want to buy new pilot jets. Half a turn makes a lot of difference. A roller clutch also helps with belt life and running cooler clutches. However, I have found that a 48/40 helix does not work very well in the mountains. I would think that you need a helix along the lines of 41/35 with the green spring.
LoneViper
New member
I'm even a little lower yet in gearing, 20/40 . I swear by Ultra Max 3 belts, not much slip with them and no belt dust.
..SNAKEBIT..
VIP Member
GEARING?
are you running 8 tooth drivers?
I'm running 9 tooth 136 x 1-1/2 and need to gear down!
running 21 - 38 now. what can I run with stock chain? 20 40?
are you running 8 tooth drivers?
I'm running 9 tooth 136 x 1-1/2 and need to gear down!
running 21 - 38 now. what can I run with stock chain? 20 40?
clutch heat
I am also running nine tooth divers, I have not had any problems with the 21/40 gearing with a 151x2 track. Sled ran about 1900 miles on the stock belt in the mountains. If you have the 68 link chain you can change to gearing.
I am also running nine tooth divers, I have not had any problems with the 21/40 gearing with a 151x2 track. Sled ran about 1900 miles on the stock belt in the mountains. If you have the 68 link chain you can change to gearing.