I have a Comet 103hpq on my 2000 Prairie 400 and trying to decide what ramp weights I should use at 10,000’ elevation. Anyone using a Comet at altitude and can tell me the weight of their primary clutch cam arms?

In years past I have just jetted carb down from 145 main to a 135 main and it runs fine. Just wondering how much performance I might gain by installing lighter clutch weights and what weight I should use.

My service manual shows weight number for altitude for kawaski arms but doesnt state how many grams the weights are. If someone knows the actual grams of these kawasaki weights, I could reduce my Comet weights by the same and be close.

Does anyone know the weight of these:
Kawasaki #39152-1053 for up to 1700’.
Kawasaki #39152-1060 for 7700-10,700’.

Comet 103 hpq stock weight is A-18 215400A1 52.7grams. This is what came with clutch years ago and work perfect at 1100’.
Available replacement options I have been given by Comet. They couldnt tell me which would be best for 10,000’:
A-15 214255a1 50gram
A-1 207889a1. 48.5gram
AB-2 208457a1 47.7gram

 

Can't help, but I am baffled as to why altitude would make any difference to the variator. Jetting yes, as the air fuel ratio depends on air density but surely centrifugal force exerted by the weights at sea level is the same as that at 10,000 feet. Can anyone enlighten me?

 

As you increase altitude the engine produces less power.

Carb needs to be jetted leaner to prevent the engine from running too rich, but power loss is still happening. Approx 3% power loss for every 1000’ elevation gain.

Now, imagine the primary clutch spinning and the cam arm weights start to press the clutch sheaves together, but now you are at 10,000’ and the engine is operating at roughly 70% of the power it had at sea level.

The engine doesnt have enough power to engage the primary clutch and maintain rpm, so if you have lighter weights for the primary cam arms, it will allow the engine to spin faster and maintain engine rpm. It is a thing, thats why Kawasaki offers clutch weights for altitude.

I have ridden snowmobiles since 1992 and the manufacturers all provide recommended weights for various altitudes, as well as spring rates and the aftermarket has countless alternative ways to adjust weights, some of which have calibrated cam arms with holes tapped in them so you can add or remove weight by replacing allen screws, etc. Most sleds are fuel injected these days so clutching is the only thing to dial in.

 

Interesting, though as revs drop the front pulleys open and ratio drops until revs and ratio are correct for the speed the bike will climb a hill. Weights would have to be a long way out before a condition similar to "loosing your revs" on a manual bike, could occur. I personally find most variator bikes are way too low geared, though don't travel over rough terrain or tow trailers, so may not experience the problems a high geared bike might encounter when doing these things. Drove a 400 King Quad yesterday, seemed woefully slow for revs it was doing. Whereas a 500KQ that I drove last week always seemed to be in the right gear.

 

You do not gain any performance buy increasing or decreasing the weights.
All it does is change the engagement rpm’s around in the primary clutch.
It is a response change not a performance change.
Performance comes from engine displacement and air /fuel mixture.

 

Clutch weight has a direct effect on engine rpm and if the engine isnt revving as high as it should, performance will decrease. Here is a good video which explains