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Discussion Starter #1
here is the story I have a 1972 bombardier valmont alpine witch I have a 900cc 3 cyl kubota diesel in that I will be machining a adapter for to mount a p85 polaris clutch on becasue they are easy to work on and I have a relatively new one on hand, the chain case is a modified yamaha vk 540 chain case so I have high, low and reverse and I am using a yamaha enticer 2 secondary clutch and jackshaft because its what I had on hand and the enticer 2 jack shaft had the same spline and the vk chain case.

so now that you all know I'm crazy and what I have built I need help with the clutching, for the diesel I need the clutch to engage at ~1000RPM and I would like for it to hold ~3000rpm while driving. max RPM on this engine is 3600. so if anyone can point me towards what weight spring to use and what weights to start off with as a baseline that would be great becasue I am lost in the dark on this one.

here are some pics. dont mind the mess.







still need to shorten the jack shaft.
 

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I am Spartacus
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23,863 Posts
That is going to be next to impossibe since most clutches don't even ENGAGE until about 3000RPM. Not sure if you can modify your existing spring?
 

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An easier way to achieve proper engagement may be to step up the clutch shaft rpm to nearer to stock snowmobile rpm.
Otherwise, use the heaviest weights (68+gr) and the lightest spring you can find.
You might look up the "clean sled challenge" and see what they did with the diesel that was used by the University of Buffalo team.
 

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Discussion Starter #4
the lightest spring I can get on royal distributing is 125# start and 260# finish. and they sell weights up to 82 grams. I have a buddy who is a mechanic at a polaris/yamaha/artic cat dealership so I might go pay him a visit and see what the lighest spring i can get from cat or polaris is, maybe one from a ATV or something?
 

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Leaves in belly pan, BAD!
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317 Posts
That's just cool.

"so now that you all know I'm crazy and what I have built I need help with the clutching"

Step up the RPM's like RJ said. If you can get to around 4~5,000 you should be ballpark.
 
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