turbo viper clutching

[tar]

So I have the first ride under my belt. Sled runs awesome and is butter smooth.
I usually hate the ride in and out because the trail gets wooped out but the viper just eats up the bumps.
I have the MPI stage 1 turbo kit. My viper would over rev instantly to 9100 and hit the rev limiter. So I could only get about half throttle all day but even at half throttle it is fast.
My question is how many grams is required to keep revs down?
I was sent some rivots for the cam arms couple springs and a new helix. If I remember the cam arms only weighed 50 grams? I was thinking they where to light for the sled but I'm new to Yamaha clutches so I put them in.
Any suggestions would be appreciated.

Thanks Tar

 

[Matt@MPI]

What set up do you have now? Springs? helix? What Rivets?

 

[BOOSTD]

What elevation are you riding?

Stock weights and rollers work great with the correct rivets installed. No need for new cam arms.

 

[turbo800]

I'm running the factory 180 kit. Dealer is dragging their feet with clutching. I ride 6000-10K'. Running factory G-W-G spring and weights. What rivets do I need? Part #'s?

 

[motojunkie101]

180 kit clutching I'm running:

Stock weights with13.3 steel in the heel and 13.3 aluminum with the hole in the tips.
42/46 mpi helix
blue white blue primary spring.
White white secondary with a good twist.

Hits the rev limiter on the trail but pulls great in the powder. I didn't get a chance to see the gauge for exact rpm yesterday because the snow was deep and I was dodging trees.

 

[tar]

Thanks guys,
My current set up
Blue- wht- blue primary spring
Stock viper cam arms 8BU 10 with a17.2 rivet and a 13.3 rivet
8BV-17604-71-00 47* set to 6-1
Wht-Wht secondary spring.



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[tar]

Elevation is 3000 7000


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[turbo800]

180 kit clutching I'm running:

Stock weights with 13.3 steel in the heel #90261-06019-00
and 13.3 aluminum with the hole in the tips. #90266-06001-00
42/46 mpi helix
blue white blue primary spring. #90501-583L0-00
White white secondary with a good twist. #90508-60016-00

Hits the rev limiter on the trail but pulls great in the powder. I didn't get a chance to see the gauge for exact rpm yesterday because the snow was deep and I was dodging trees.

I added some part #'s to help people out with your setup.

When you say "good twist" what exactly does that mean? I think I read Ulmer recommended going from 3-1 (40*) to 6-1 (70*)

 

[Matt@MPI]

Thanks guys,
My current set up
Blue- wht- blue primary spring
Stock viper cam arms 8BU 10 with a17.2 rivet and a 13.3 rivet
8BV-17604-71-00 47* set to 6-1
Wht-Wht secondary spring.



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How much boost? If your running high boost then change out the 13.3 to 17.2.

 

[tar]

The boost level is preset,5 to 6 lbs?


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[tar]

I think I need to add more weight than a different rivet.
This is your kit Matt, I need some good info how to clutch it.
I need to know what you run in your stage 1 kit.
Pm me if you don't want people to know.
Tar

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[turbo800]

I think I need to add more weight than a different rivet.
This is your kit Matt, I need some good info how to clutch it.
I need to know what you run in your stage 1 kit.
Pm me if you don't want people to know.
Tar

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Some guys are running the 8FS (65.5g) or 8FP (67.8g) weights instead of the 8BU (45.4g) weights. They also have a more aggressive curve instead of the flatter stock curve.

 

[tar]

Some guys are running the 8FS (65.5g) or 8FP (67.8g) weights instead of the 8BU (45.4g) weights. They also have a more aggressive curve instead of the flatter stock curve.

Bingo that's what I'm after thank you.
What I have now is only 53 grams changing one rivot will not add the weight I need.

Tar

 

[turbo800]

The 8FS weight is $72/ea. Part #8FS-17605-00-00

The 8FP weight is $36/ea. Part # 8FP-17605-00-00


I'm gonna try the second one for half the price...

 

[Matt@MPI]

Bingo that's what I'm after thank you.
What I have now is only 53 grams changing one rivot will not add the weight I need.

Tar

I don't think I would run out and buy Yamaha's most expensive weight's they make without working with what you have first. Just changing the weight to a different profile will also require possible changes to springs, helix, etc. The total weight is just a reference, profile has a lot of effect on how everything else works. Do you know how much boost your making or are you assuming it came from MPI set at 5-6? What I'm getting at is what did the dealer change it to? The set up you have should handle 5-6 psi at you elevation just fine. We're missing some info here.

 

[Matt@MPI]

Some guys are running the 8FS (65.5g) or 8FP (67.8g) weights instead of the 8BU (45.4g) weights. They also have a more aggressive curve instead of the flatter stock curve.

I would disagree on the 8FS being more aggressive. I think its just the opposite. We've been big fans of the 8FS for years but the 8BU-10 is a very responsive weight and works very good on the Viper.

 

[Matt@MPI]

Bingo that's what I'm after thank you.
What I have now is only 53 grams changing one rivot will not add the weight I need.

Tar

One more point. Last year we ran the Viper kit with 8FS with 2 17.2/4.5 grams ea. and 1 of our custom 7.0 gram rivets. So that's a total of 81.5 grams. Yes the profile makes a huge difference not just total weight.

 

[tar]

Do you know how much boost your making or are you assuming it came from MPI set at 5-6? What I'm getting at is what did the dealer change it to? The set up you have should handle 5-6 psi at you elevation just fine. We're missing some info here.[/QUOTE]

I opened the box, the dealer didn't touch the kit. I installed the kit myself.I didn't change any thing.I did check at what PSI the waste gate would move. It would start to move about 5.5 psi.

I would be willing to change the rivets but as fast as it over revs I don't think rivots are enough.

Tar

 

[motojunkie101]

I added some part #'s to help people out with your setup.

When you say "good twist" what exactly does that mean? I think I read Ulmer recommended going from 3-1 (40*) to 6-1 (70*)

I'll have to check what holes I've got the spring in. I tried 6 and 1 and couldn't get it twisted far enough so I went with what I could get twisted by myself. It worked fine yesterday, but I'll have to ride a little more to see how I like it.

 

[Matt@MPI]

I'll have to check what holes I've got the spring in. I tried 6 and 1 and couldn't get it twisted far enough so I went with what I could get twisted by myself. It worked fine yesterday, but I'll have to ride a little more to see how I like it.

6

6 and 1 is a tough twist that's for sure.