Viper ltx turbo clutch slipping baddly

[johan]

I'm working on a friend's viper with 270hk. We are getting a lot of slipping when doin takeoff. What do we need to do. More spring in secondary or less helix?

The machine has heavy hitter, 911, stock primary rollers, orange primary spring and a 8dn belt. secondary we have tested big venom spring twisted to 60 to 80degree, stock spring twisted to 60-80 degree Dalton red twisted to 60-80 degree. 45 helix.

The clutches don't run hot but hammering gas from beginning the belt is snapping.

Rpm whit stock pink spring is in takeoff 9600 then it falls to 7800 after 1.5second then it climbs to 9000rpm and stays there. If we go wot from 30km/h it goes to 9000 and stays there.

What do we need to do for change? More weight in the middle hole, 14.5rollers? More spring in secondary

 

[Studroes144]

Does it do the same thing with the shorter 8jp belt? That high rpm on launch and then lugging way down could be from too long of a belt and the clutches are shifting hard before the belt is stretched enough to actually move the sled..then once the clutches have enough tension on the belt to keep the sled moving they're shifted out too far and sled don't have the power to pull it. On the sleds I've owned I've found that almost all of the weird quirks in clutching can be eliminated buy using a belt with more grip and also the proper length. I've ran gates 8jp length carbon belt for 3 season without a single issue..I switched to that belt because mine would do exactly what yours is doing..since then the sled has ran faster and quicker in all types of riding along with much more consistent. Improper belt on the sled will make it nearly impossible to get the sled clutched right, you can change a bunch of stuff and get it to work good, but that doesn't make it efficient.

 

[yammitrip1]

It sounds like your sucking the belt, N/a guys can do this with to soft s secondary spring. I did it last weekend. Going 5 mph on fresh snow (10 inches of powder). Hammered the throttle and track quickly dug to the dirt and hit rock hard grass and grabbed. Belt was still in bottom of secondary but track came to a halt. Pure belt slippage for 50 ft or so until it worked it's way back up.

Peak rpms are correct right? It sounds it. But the sled is upshifting to fast too fat that it's getting ahead of the engine, I'd try a different helix, and if you have a set of 14.5 rollers I'd throw them in too.

 

[johan]

Yeah my own machine with 270++ never do this but I have roller converted it. I was thinking the same. I am going to try stiffer spring first

 

[Kenzie]

Not sure if I missed it or not but I was advised the original blue secondary spring in big venom kit doesn’t keep up enough for boosted applications over 8 psi. Not totally sure where I read that maybe someone could chim in on that.