Not getting full shiftout

[Studroes144]

Complete clutch kits, especially on the new sleds, are really gonna be hard to gain much. Top speed for the viper more than likely isn't going to change with a clutch kit. Proper setup will gain more low-mid range power generally however certain kits are geared more towards low end and others more towards top end. The thing with using just adjustable weights you are only focusing on engine rpm. Aftermarket weights will be slightly more aggressive than stock in some cases but the main purpose is to get the rpm where they need to be. A complete clutch kit is designed to get the sled to shift out as fast as possible while still maintaining peak rpm. When you start messing with that aspect of clutching it can be very hard to gain. As far as just swapping out weights it's very straight forward. The magnaforce weights that I use from D&D have 4 holes in the weights and they come with small magnets. If the engine is over revving at lower speeds than add weight and vice versa for under revving. Same thing with mid range and top end. Very easy to tune and very effective once u get the rpm where it needs to be

 

[TurboJamie]

The thing that kills a sled the most is when it revs high at first and then falls off a few hundred rpm. That takes a long distance to really make that up for the rpm to come back around. Seems to me like these posts all say the same thing. Rpm isn't getting quite high enough and then it falls off. There are aftermarket weights out there that will take care of that problem and are very easy to install and tune. Any aftermarket clutch kit maker I'm sure can send you a set of weights to throw in and be pretty darn close if not spot on for rpm and you won't have to pay the $350-$400 price of a complete clutch kit

I have to be honest with you Studroes, last year I bought a clutch kit, air box and pcv from a very popular company for my 2011 apex, I had a lot of problems with hitting rpm and slipping the belt, needless to say the "customer service" wasn't the best and after weeks of trying I finally took the parts off and returned the sled to stock, it was faster stock. I don't have a lot of faith in some of the aftermarket performance companys after I spent $900 and got slower.

Good story and I follow the same rule. Unless its a turbo usually I just don't have the time to build kits. But clutching and tuning I still do to ensure its the way I want.

You by the sounds of it weight wise could benefit from just lightening the tip weight in your sled or simply upping the spring pressure in the high end. What model of Viper do you have or do you know the primary spring color in yours?

For example say you have a 25/130 spring in it you could go say 25/150 and probably be pretty close.

 

[snowbeast]

Not sure what the op was expecting. Yamaha clutches do not shift the belt to the top of the sheve. Were also dealing with a 130 hp sled, with big tall suspension and a big track. Imo on a stock viper 90/100 conditions dependent is pretty good. Guys need to pay zero attention to the " my sled does 105 something is wrong with yours" type comments. Conditions conditions conditions! The only thing that makes mph day in and out on soft trails is turbo power.

Thats right,when you turn up the wick on a turbo,dont really matter what conditions you are on,it will always turn better than 100 mpg gps,i see 112-114 most all the time on our small rr bed in crappy conditions gps,but have not had good bare ice yet,so dont know what its top end is,and that will also depend on what map i run.

 

[cannondale27]

These sleds stock must run about 9000 rpm or they just can't pull in poor conditions. Why some stock won't I don't know. Here's a kicker. I did nothing but pull limiter straps 1 hole tighter from stock setting of all the way out. Found a nice section of grade and I got 101 and climbing! Surprised me. Did limiters help? Never did it before with 1000 mi on believe me I tried.

 

[NOS-PRO]

Steve - I told you up 1 hole on the limiter strap works

Hopefully I can find that section of rail road grade you were on and bring the radar. My GPS will work also.

Almond1000 - I kept everything stock in the primary and played around with a helix and spring percentage on the secondary. Result was I gained 8mph on top end and my rpms are 9,030 max. Just over 500 miles on the sled. I have a ton of helix's from my racing years and ones that I purchased.

Radar run this weekend in Manitowoc - will post pics and results.

 

[almond1000]

The thing that kills a sled the most is when it revs high at first and then falls off a few hundred rpm. That takes a long distance to really make that up for the rpm to come back around. Seems to me like these posts all say the same thing. Rpm isn't getting quite high enough and then it falls off. There are aftermarket weights out there that will take care of that problem and are very easy to install and tune. Any aftermarket clutch kit maker I'm sure can send you a set of weights to throw in and be pretty darn close if not spot on for rpm and you won't have to pay the $350-$400 price of a complete clutch kit

I have to be honest with you Studroes, last year I bought a clutch kit, air box and pcv from a very popular company for my 2011 apex, I had a lot of problems with hitting rpm and slipping the belt, needless to say the "customer service" wasn't the best and after weeks of trying I finally took the parts off and returned the sled to stock, it was faster stock. I don't have a lot of faith in some of the aftermarket performance companys after I spent $900 and got slower.

Good story and I follow the same rule. Unless its a turbo usually I just don't have the time to build kits. But clutching and tuning I still do to ensure its the way I want.

You by the sounds of it weight wise could benefit from just lightening the tip weight in your sled or simply upping the spring pressure in the high end. What model of Viper do you have or do you know the primary spring color in yours?

For example say you have a 25/130 spring in it you could go say 25/150 and probably be pretty close.

I will look after work and see what springs are in it, I never paid any attention when I had panels off before, it is a rtx se and all I did to it so far was add 135 studs and pulled the limiter straps up 1 hole from all the way out

 

[cannondale27]

NosPro the river has come around. Not perfect but safe enough for some high speed runs again!

 

[almond1000]

Steve - I told you up 1 hole on the limiter strap works

Hopefully I can find that section of rail road grade you were on and bring the radar. My GPS will work also.

Almond1000 - I kept everything stock in the primary and played around with a helix and spring percentage on the secondary. Result was I gained 8mph on top end and my rpms are 9,030 max. Just over 500 miles on the sled. I have a ton of helix's from my racing years and ones that I purchased.

Radar run this weekend in Manitowoc - will post pics and results.

what model viper are you on?

 

[NOS-PRO]

Which river Steve? Just called park hotline, everything is open except section 1 yet, might hit the railroad grade tomorrow afternoon.

Almond1000 - XTX Viper

 

[journeyman]

Whenever I see a post like this the first thing I think of is marking the primary clutch sheave and seeing if I am getting a full shift out.

I had to scroll this thread a bit and hats off to skidooslayer for pointing it out and Turbojamie for pointing out that the YAMAHA clutches do not use 100% of the face. If you wipe off all the ink except for the top 1/4" you are attaining full shift.

As for clutch kits.....be very leery of these supposed kits. Been there and done that too many times. Each sled is different, each rider is different in physical aspects so there is no one do all kit for everyone and every sled. Allot of variables go into play. If these outfits didn't spend hours and hours testing in real world conditions you may be throwing your hard earned cash away. I do know the Ulmer kits are pretty solid though. Those guys do their homework.

With my own experiences I like to use a sparring partner in a test field or runway of open space . Mark the clutches as said, if they are not shifting out or not reaching my desired shift rpm then it's time to go to work using your sparring partner as a benchmark. Yamaha likes to engage their clutches a bit low sometimes around 3500 rpm. I usually find a spring with stronger preload but the same shift rate. This way I can bump up my engagement to say 4000-4200 rpm's. Personally I like Heavy Hitter clutch arms. So easy to change/load the weights instead of pounding rivets. I have no stock in that company but have literally thousands of trouble free miles with them in Yamaha clutches.

As for hyfax wear, dragging etc....that needs to be remedied first before any clutching stuff goes on. You need a free rolling chassis first and foremost.

 

[Studroes144]

I agree 100% with the free rolling chassis! I'm just getting to wear mine is really rolling nicely again. My slides are worn bad so waiting for the duponts to come in. So far mine has responded well to the extra wheels on the skid. I'm going to add atleast one more set. The suspension on these sleds is very stiff and people don't realize the drag that puts on a sled. Was testing today with a friend who has a base ltx with very similar clutching. He has duponts, I have 1 set of extra wheels with worn hyfax. He is setup on softest settings, I'm setup in middle settings on torsion blocks. Ran 10 times in 1000' and he could pull me by 2 sled lengths. He was running 94-95 mph I was running 90-91. We both weigh sighing 20 pounds so no big weight difference. I then switched my torsion springs to softest setting and that is it. I went from getting beat by 2 sled lengths to beating him by 2 sled lengths. Fastest speed I seen then was 97mph. Simply by loosening up the rear torsion blocks I gained 4 sled lengths and 6 mph in the same exact field doing back to back runs. Simple things make an amazing difference. All that to me goes to show that the stiff suspension on these sleds and not being able to roll freely affects them tremendously! Do what journeyman said and get the sled rolling freely and it will perform. I can say already that extra wheels or worth the money and the duponts I'm sure will be an improvement. No doubt with new slides I'll be hitting 100+ mph in the same distance with a totally stock sled with clutching and it is a rocket getting there. Address the chassis issues first, then worry about clutching if it's not suitable.

 

[almond1000]

The thing that kills a sled the most is when it revs high at first and then falls off a few hundred rpm. That takes a long distance to really make that up for the rpm to come back around. Seems to me like these posts all say the same thing. Rpm isn't getting quite high enough and then it falls off. There are aftermarket weights out there that will take care of that problem and are very easy to install and tune. Any aftermarket clutch kit maker I'm sure can send you a set of weights to throw in and be pretty darn close if not spot on for rpm and you won't have to pay the $350-$400 price of a complete clutch kit

I have to be honest with you Studroes, last year I bought a clutch kit, air box and pcv from a very popular company for my 2011 apex, I had a lot of problems with hitting rpm and slipping the belt, needless to say the "customer service" wasn't the best and after weeks of trying I finally took the parts off and returned the sled to stock, it was faster stock. I don't have a lot of faith in some of the aftermarket performance companys after I spent $900 and got slower.

Good story and I follow the same rule. Unless its a turbo usually I just don't have the time to build kits. But clutching and tuning I still do to ensure its the way I want.

You by the sounds of it weight wise could benefit from just lightening the tip weight in your sled or simply upping the spring pressure in the high end. What model of Viper do you have or do you know the primary spring color in yours?

For example say you have a 25/130 spring in it you could go say 25/150 and probably be pretty close.

I will look after work and see what springs are in it, I never paid any attention when I had panels off before, it is a rtx se and all I did to it so far was add 135 studs and pulled the limiter straps up 1 hole from all the way out

I pulled the side cover and looked at the clutches and springs tonight, I never drew a line on the faces but you can tell by the slightly different color that the belt is getting within a 1/4" of the top of the primary and running down as far as I can see in the secondary, spring colors in the clutches are a blue-silver-blue in the primary and a pink in the secondary. RTX SE

 

[1049triple]

Ryan466, I would check if your throttle bodies open at their maximum, mine was not and the sled was turning low rpm's like your. It is possible now for the cable to be too lose and the throttle does net open completely.

 

[ryan466]

Thanks I will check that also when I pull it into the heated shop this weekend and look the sled over again try and also find out where my chaincase oil is disappearing too

 

[cannondale27]

Wish I could do one thing at a time but Duponts,lighter rear spring,Shock tune and couplers on 1 tested tomorrow.