Poo guys are not going to like this

Here is a video of a Viper with a clutch fix I devised. Seems Viper has a primary clutch issue needs fixed, see bottom of this post for details.

So this guy has a very good running Nytro that beats his Viper. He does the clutch fix and check the diff. 4 lengths plus on the Nytro. I had the same results at 10k (weights adjusted for altitude) as he did in the great lake area. This is not a minor adjustment for us it REALLY woke up the Viper. Please note that he was at low altitude so he used the 8FP weights with no grinding, not the cut down 8FS I used.

https://www.youtube.com/watch?v=JeiNuxIomcE






Its lost in the clutch, the primary actually. After the 8DN debacle (changing from 8jp to 8dn stopped wild rpm hunting) I went to work studying why this sled was so different from the Nytro clutches. I noticed our Viper came with a 2 stroke profile in the weight. That being a bump in the heel to raise take off revs (as 2 stroke have high horsepower not torque) and then a level ramp for about a third of the profile then a steeper ramp to raise rpm. And yes, why? This is a torque motor not a 2 stroke. I put the flat profile Nytro weights in (Matt from MPI suggested this, and this is what I did to our other boosted Yamahas so it wasn't anything new) and cut to desired rpm and that helped but it still seemed like something was missing. I mean this sled is a lot lighter than a Nytro and should be faster. So I came up with a bizarre test that worked.

All tests with flat profile 8FS weights cut down to 50 grams for above 10k altitude running. Weather about 25 degrees 3 inches snow on top of crust at 10k altitude. Race against 2008 Nytro with Can and a few add ons and a 2012 Nytro with 190hp Turbo


1. Stock clutches - Primary spring 35 open, 101 Shift -----------------------------------------------------Viper slightly slower than Nytro, Turbo blows it away

2. Stiffest primary spring made for this clutch (that I could find) Primary 45 open, 135 shift------------Even up with Nytro, turbo blows it away

3. Green-White-Green (aka Primary 45 open, 135 shift)with 2mm spacer -------------------------------------Viper blows away Nytro, and runs about one length slower than Turbo Nytro from stop to 50mph. Viper doesn't taper off at around 50mph and keeps pulling.

My results yours may vary.

OuraySledder said:

The only thing that is going to bother the Poo guys is if their riding buddies are fool enough to buy a new Viper. Fortunately I have equipped my Pro with a shovel large enought to cope with the Vipers wieght.....

Click to expand...

Neil from BOOST-IT says,

Originally Posted by polarcat39
Can you elaborate for a rookie on why it's 9 out 10 times? Is it the power difference for hill climbing? Handling ability? Reliability?

We know the reliability is better and belts are less than half of the price. I can get more power out of less octane, and you can't even compare the torque.
The deep snow handling is actually better on the Viper, and the power band is much more manageable.
The Viper also rides better than my Pro on the trail, not to mention the engine vibration is non existent with a four stroke.
We ride a lot of icy trails in the spring and the Polaris cooling system is not the greatest.
With the Viper I don't have to add oil every couple days, and my clothes don't smell like two stroke smoke.
The Pro turbo is good at a lot of things, and I really enjoy it....I just prefer the Viper so it gets the miles this season.



I can believe him.....or you? :face-icon-small-win