Clutch tuning/which weights? Need a master's help!

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Figgy

New member
Joined
Apr 29, 2009
Messages
42
Age
53
Location
Chicago
Ok all...dunno if I posted this before...but I'm trying to begin the process of clutch tuning. And...I've never done it before, and have little base of knowledge. Here's what I have done to give a clue as to my mechanical prowess:

1) Many car engine full rebuilts, push rod motors, but mostly jap stuff, SOHC, and DOHC stuff.
2) Did my first four cylinder street bike engine R+R and complete disassembly/reseal this summer.
3) PWC motors, R+R, rebuilt, etc.
4) Lots of sled motors, r+r, rebuilt
5) Two stroke dirt bike motors-
6) Boats too

To keep it short, I've repaired just about anything that burns gasoline, so I'm far from mechanically inexperienced. But clutch stuff on a sled...I"m lost.

Here's what I'm attempting to tune:

http://www.totallyamaha.net/forums/showthread.php?t=62488

Got almost no action on this post:

http://www.totallyamaha.net/forums/showthread.php?t=65647

I know the stock weight on the primary is the 8DN-10 for a mountain Viper, which this is/was. The machine has a different torque cam in the secondary (don't know which one, maybe a different spring too) and if that matters much. Also, I'm sorry I don't know this either, which weight is in it now. I'm pretty sure it's clutched for elevation of somewhere around 8k feet.

Clearly I'm trying to find the correct weight so I can either put a pin or two in it and have weights for sea-level riding and weights for in the mountains. And I'd really like to find the right one the first time.

I have two Vipers (one with a 121 and triple pipes too) and a '99 SRX 700 that I could steal the clutch from and see how it worked on the Mountain sled. However, that would require snow...which I don't have.

Lastly, and I hope someone can help me here, how do you know when it's clutched right? I mean I'm sure I'd know if I'm in the power-band and it feels like she's running properly, but is there anything else to look for? Or is it all seat-of-the-pants stuff?

Thanks in advance-
 
the whole idea is to shift it as fast as you can and hold shift rpm but alot comes into play some motors you can lug harder on the bottom and let it catch itself a old clutch guy told me torque throws the sled out and hp holds it
 
Cool...thanks for the reply...

Does anyone know the difference between the stock Viper weights, the 8EKs I think they are and the "Deep Snow Special" which has the 8DN-10s for stockers I do believe?
 
There is sooooooo much clutching info on here that it is not even funny...Best thing I can tell you to do is read tell your eyes bleed :twisted: Its all about testing and making sure your sled is running the right rpm out of the hole in the middle range and on top!!! Research what others are riding with and punt!!! Its what we all do....oh and your going to need snow!! There's a ton of info in the tech section of the forum about the shift out ramps on different weights, spring rates and roller info. Oh and I recommend OLAV AAEN'S clutch tuning hand book(It was recommended to me)!!! It has great info on clutching and how it works. Good Luck!!!!
 
Last edited:
Figgy said:
Cool...thanks for the reply...

Does anyone know the difference between the stock Viper weights, the 8EKs I think they are and the "Deep Snow Special" which has the 8DN-10s for stockers I do believe?
Click to expand...


8DN-10 are 39.76 grams unloaded and the 8EK are 39 grams unloaded, with a slightly different ramp. Either weight can work well, just need the other components, What is the colors on the Springs? what does the Helix say on it for numbers? What is the twist at? look at hole in helix and clutch sleeve , Add numbers together for secondary tension... Let us know.
 
Thanks a ton guys...I dunno a darn thing about any of this. I will check on the Helix, and the spring, I got the stocker too.

So if I'm reading this right, I can go ahead and get the 8EKs that a forum member will sell me and they will work fine? I mean from the standpoint of physically fitting, I know they are lighter.

Also, couldn't I make up the difference in weight with those little plugs that you drive into the weight? Or are they collectively less than .76 grams/are you only supposed to be one in at a time? I presume the weights all have two holes?? I know the 8DN-10s do...got a picture of it in the ole manual!

Does anyone know if the Clymer (think that's the manual I have) has any good clutch knowledge to impart to me? Unfortunately it's with my sleds, at my mom's some 30 miles away...

Olav's book sounds good too!

And yeah, some snow would be really nice to help with all this...I don't want to tune on the trail or mountain... :-(
 
Do a search for clutching tips!!!!!!! Then go to the Snowmobile Tech page!!!!!! Listen to Riverrunner read, read, read, and then read some more cause the clutching issue has been covered so many times on here that nobody should really need to ask any questions about it.
 
i get that the newer guys don't realize how much clutching, cans, reeds, and so on have been covered, then they don't get many replies and don't know why. search first then ask questions to clear up specifics. of course if everyone got their answers from searches i'd have nothing to read
 
No I kinda figured there had to be some info out there, but I was being lazy and hoping some forum member might post a "good" like to a thread. But I can as they say, feed myself. I'll do a search and see what comes up.

Anyone have any thoughts on the end of post #7? Can I go ahead and use the 8KE weights or would this likely not be a good idea?
 
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