Changing Engagement

GP396

GP396

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Dec 22, 2006
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Will Comet clutch springs fit a stock Yamaha clutch on a 78 EX440?

Is there a Comet Chart somewhere showing the pre-load engagement and rates on the various color springs?

From what I can figure with limited data I have on this stock Yamaha spring (pink/white) is that it is 3.09" long and has a rate of about 98.5lb per inch. I don't have any pre-load engagement info other than 3000-3200rpm's seems low.

If there is a chart available I could figure out a couple Comet springs to give a try, providing they will fit.

Or in the alternative if there is a chart for the Yamaha springs giving the same information. Not looking for a race set-up, just something around 3700rpm

Any help appreciated.
 

I DON,T THINK COMET SPRINGS WILL WORK IN YAMAHA PRIMARY. IF I AM WRONG, SOMEBODY POST. I WOULD TRY ADDING AFEW SHIMS TO YOUR YAMAHA PRIMARY. THIS WILL RAISE ENGAGEMENT SLIGHTLY. 3:16 (yammie tony)
 
Where abouts?

YAMMIEGOD

Sorry for my ignorance, but what am I trying to shim out? Am I adding more of an existing part or will I need to find something to work? How much thickness is a good starting point.

Thanks for the help

ClutchDiagram.gif


I did find some dimensions and rates on the Comet Springs so I can do some measureing on the fit question.
 
YOU WOULD BE ADDING THE SHIM WHERE # 9 PRINARY SPRING SEATS IN SPIDER. THICKNESS DEPENDS ON HOW HIGH YOU WANT TO INCRESE ENGAGEMENT. YOU ALSO CAN ADD SLIGHT NOTCH TO WEIGHTS #18 TO INCRESE RPM. I THINK THE ISSUE YOUR GONNA HAVE WITH COMET SPRINGS IS LENTGH. ONE MORE SUGGESTION IS TRY A SRX 440 SPRING. I MIGHT HAVE ONE FROM A 1980 SRX THAT MAY GET YA RIGHT ON. !! 3:16 (yammie tony)
 
Ok, that makes sense.

The info for the Comet springs shows about 6 springs that are within 1/32 to 1/16" of the stock spring length

Learning as I go here, and now knowing that length(as modified by shims) will impact pre-load and thus engagement, I can see where length would be an issue. Did I get that right? Would 1/32" have that much of an impact.

Sure would be nice if Yam had a chart showing the data on their springs that would just let me pick the next up pre-load and stick with a similiar compression rate.

I'm interested in the SRX spring. Also intersted in the mechanics behind why you think that would be a good fit if you're in a teaching mood.

E-mail me a price and address and I'll have my agent send you a check for $25K and ask that you send the difference back along with the spring :mrgreen:

markinsaginaw@sbcglobal.net

Thanks for the help.
 
I think you can shim to a certain point, then you get what they call coil bind, someone told me that once. We used to shim the arctic cat hex clutches, but only put one washer under the spring. If anyone has a primary spring for a ex440, let me know, or yammiegod, if gp396 does'nt take yours I may be interested. Or even interested in a very good shape 102, with or with out gear.
 
GP396 said:
Ok, that makes sense.

The info for the Comet springs shows about 6 springs that are within 1/32 to 1/16" of the stock spring length

Learning as I go here, and now knowing that length(as modified by shims) will impact pre-load and thus engagement, I can see where length would be an issue. Did I get that right? Would 1/32" have that much of an impact.

Sure would be nice if Yam had a chart showing the data on their springs that would just let me pick the next up pre-load and stick with a similiar compression rate.

I'm interested in the SRX spring. Also intersted in the mechanics behind why you think that would be a good fit if you're in a teaching mood.

E-mail me a price and address and I'll have my agent send you a check for $25K and ask that you send the difference back along with the spring :mrgreen:

markinsaginaw@sbcglobal.net

Thanks for the help.
Click to expand...
I don't think 1/32, or 1/16 would make a big diff, we went to the hardware stores and got washers for that. If I remember correctly, we only used one washer at a time. maybe someone has done it recently, and can tell us what one washer will raise the engagement.
 
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YOU WANT YAMAHA SPRING SPEC,s. I GOT THAT !!!!! TAKE ME AWHILE TO FIND IT. THIS IS ALL VERY SIMPLE. THE SPRING FROM THE SRX WILL GIVE YA HIGHER ENGAGEMENT BECAUSE ITS STIFFER IN LAYMEN TERMS. ANOTHER WORDS HIGHER PRE-LOAD. ONE PROBLEM IS YOUR GONNA PULL YOUR HAIR OUT TRYING TO FIND A DEFFERENT SPRING TO USE IN THAT EXCITER, ESPECIALLY YAMAHA SPRINGS. WLS IS CORRECT, SHIMS WORK, BUT YA MUST BE CAREFUL BECAUSE THEY WILL CAUSE BINDING. LET ME DO SOME DIGGING FOR YA. 3:16 (yammie tony)
 
on my 78 ex440, we use a 102, with purple spring, and A-23 weights, the 23's are notched weight, also they will give a higher engagement. this is a race sled though. engages abot, the paper says about 4200, but I think ours engages about 4800, according to our factory tach, which is probably off.
 
Thanks

Appreciate all the help here.

WLS, I bought an OEM primary spring for my EX from these guys this fall. I may have even bought a second one from the local dealer while waiting on delivery. I'll take a look.

http://www.yamahaaccy.com/

Look under Yamaha OEM parts. Problem is that it's coming in around 2800-3000 vs the spec of 3300-3700 for this sled and I'd think I'd like to be at least the lower end of that. Clutch is fresh rebuild with all new OEM weights bushings, pins, etc as well.

Thanks for the comet link. I'll have to weigh one of my weights for comparison to the Comet to get one step closer on this quest..

YAMMIEGOD, certainly interested in the Yamaha spring data and SRX spring.

Let me know
 
Spring charts from '81 sales seminar

A friend at work gave these to me from the '81 sales seminar featuring the '81 SRX and Vmax.. He knew I had SRX's and he worked at the local dealer "during the day". He also gave me a '78 SRX manual and EX340/440B supplement.

Time to "pay it forward" with the info.

Good luck,

Tim
 

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DUDE, THANK YOU FOR POSTING THAT. I JUST TORE MY GARAGE APART LOOKING FOR THOSE SPEC,s. anyways i have 1980 srx yamaha clutch spring if ya want to try it. be glad to send it to ya. 3:16 (yammie tony)
 
Yammie,

Sent my address via PM

Timo,

Great info, just the kind of stuff I'm looking for. Yammigod, thanks for the effort and tearing the garage up. I know how that goes.
 
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