Clutching help/info

[Martens199]

Ok as you most know I have been having problems with my srviper that are driving me nuts!
But this one I am hitting the rev limiter at 9150rpm of the hop then it sometimes will settle down.
MCX wieghts 96grams which I can't add rivots to unless I make some.
14.5 rollers, ggg primary spring, stock secondary 41 helix, pink spring.
Now I have been suggested to try a epi cat purple spring, does cat springs fit Yamaha? There is 2 options on epi website which I can't figure out which one I would need.
Also been suggested to try a blue pink blue primary. So I got one and the Yamaha package had right part number on it but it was a yellow pink yellow in the bag....

I'm new to clutching and trying my best to learn but don't got much seat time for tests and trials.

 

[stingray719]

I have on my EVO 210/275 horsepower the following,

Dalton QAY 70 weights with the bump on the base of the ramp ground down flat (I do not like overev on takeoff). Total weight 68 grams after removing some material from the underside of the weights. I ride above 10k altitude so adjust weight for your altitude
40/46 helix
Barn Of Parts soft start primary spring
6mm worth of primary spring shims
secondary stock except helix

9200+ on 210 setting
9700+ on 275 setting (I have EVO flash that allows 9750 rev limit)
2700rpm engagement speed, smooth pull all the way up.

 

[Martens199]

I would love to get a Evo flash, but at this time just cannot afford to. Although Raising the limiter would make sense in my problem. Here is the weight I'm running it also has a slight bump at the heel. Would a slight sanding help that over rev of the hop?

 

[stingray719]

I would love to get a Evo flash, but at this time just cannot afford to. Although Raising the limiter would make sense in my problem. Here is the weight I'm running it also has a slight bump at the heel. Would a slight sanding help that over rev of the hop?
View attachment 114073

Takes more than a light sanding, but yes that bump is designed to create a higher rev at take off. You might ask why would anybody design a weight like that for a torque engine and the only answer I might guess is that they are used to 2 stroke engines. Yamaha designed a weight especially for 4 stroke engines called 8FS that the entire ramp is flat. So 4 stroke weight profiles are not new. The heart of the COTC is a flat profile 8FP (similar to 8FS but half the price)

That being said I ground the bump off my Dalton QAY 70 and now it does what I want. As with any mod there are risks - do not do - ETC for disclaimer. The pic below shows the 8GL that I ground the bump off the heel and tested, stopped the take off over rev but I wanted a flatter profile and went with OSP Viper weights for our red viper. Not telling you too (see disclaimer) but if it was me I would grind that bump off the heel to make a matching ramp all the way up, and set side by side to get angle same on all 3 and weight to get same weight. Or buy OSP viper weights that the weight is set with magnets

 

[alpineviper]

I run dalton dtya 1 weights loaded up to about 77g, blue/brown/blue primary spring with no shims. Secondary settings are as follows epi purple spring and straight 47deg helix with 0 and 3 wrap. Revs around 8500rpm at 7500ft at 8psi boost with alpine motorsports turbo kit.

 

[JustBoostIt]

I would love to get a Evo flash, but at this time just cannot afford to. Although Raising the limiter would make sense in my problem. Here is the weight I'm running it also has a slight bump at the heel. Would a slight sanding help that over rev of the hop?
View attachment 114073

When you do fall into that little windfall of cash I'm right next door for that Evo flash. The raised rev limit definately makes the tuning easier.

 

[Martens199]

I did get a purple cat spring so I will do some testing with that as well. But I only have a 43 helix to try it with. Got a blue brown blue spring to try too. But I'm gonna start with the ground wieghts. Too bad these mcx weights are none adjustable....

 

[Martens199]

Takes more than a light sanding, but yes that bump is designed to create a higher rev at take off. You might ask why would anybody design a weight like that for a torque engine and the only answer I might guess is that they are used to 2 stroke engines. Yamaha designed a weight especially for 4 stroke engines called 8FS that the entire ramp is flat. So 4 stroke weight profiles are not new. The heart of the COTC is a flat profile 8FP (similar to 8FS but half the price)

That being said I ground the bump off my Dalton QAY 70 and now it does what I want. As with any mod there are risks - do not do - ETC for disclaimer. The pic below shows the 8GL that I ground the bump off the heel and tested, stopped the take off over rev but I wanted a flatter profile and went with OSP Viper weights for our red viper. Not telling you too (see disclaimer) but if it was me I would grind that bump off the heel to make a matching ramp all the way up, and set side by side to get angle same on all 3 and weight to get same weight. Or buy OSP viper weights that the weight is set with magnets

View attachment 114079

Do you know how much weight can be loaded into the OSP weights? Doesn't say on their site just stresses that it's a low boost turbo weight.

 

[alpineviper]

I have on my EVO 210/275 horsepower the following,

Dalton QAY 70 weights with the bump on the base of the ramp ground down flat (I do not like overev on takeoff). Total weight 68 grams after removing some material from the underside of the weights. I ride above 10k altitude so adjust weight for your altitude
40/46 helix
Barn Of Parts soft start primary spring
6mm worth of primary spring shims
secondary stock except helix

9200+ on 210 setting
9700+ on 275 setting (I have EVO flash that allows 9750 rev limit)
2700rpm engagement speed, smooth pull all the way up.

so you pick up 65hp extra and only pick up 500rpm? or do you swap weights?

 

[stingray719]

Do you know how much weight can be loaded into the OSP weights? Doesn't say on their site just stresses that it's a low boost turbo weight.

Came with alot of magnets, give OSP a call.

 

[stingray719]

so you pick up 65hp extra and only pick up 500rpm? or do you swap weights?

Nope.

 

[alpineviper]

nope what? do you have to change anything? i dont get how you can make 65hp more and leave the clutching the same.

 

[stingray719]

nope what? do you have to change anything? i dont get how you can make 65hp more and leave the clutching the same.

The huge RPM spread with the EVO flash it works for me. 9200+ rpm on low and 9700+ on high. Works for me your mileage may vary

 

[silver rocket]

if your engine rpm is to high from take off to top speed you need more weight. If you over rev on take off only you can try less pretension on your driven clutch spring. Try your 43 degrees, it will drop your rpm by about 300 to 400 rpm if the belt is not slipping with the same spring you have on now.

 

[Martens199]

Yeah I went to a yellow pink yellow spring. I was going to try a b-p-b which was advised by our supplier. The spring did help a lot. I tried a purple cat spring with seemed to work well. But the secondary started to get really hot, then I blew a belt so I went back to a stock pink spring at 60 twist. Doesn't seem as responsive with the stock spring when compared to the purple.