As mentioned in a earlier post, my mm overrevs. I want to get the rpms down, but I dont want to go higher up on the gearing, steeper on the helix or softer on the secondary. I know that the primary can be tuned by adding rivets to the weights, but if that isn't enough to get the rpms down, I can go with a spring with less end force. But I don't understand, why would I want to go with a softer spring? Won't the weights just slam it easier together? Is my current primary spring too stiff for the weights? Shouldn't it be, the more power, the harder the spring?
yamaholic22
Active member
How much are you overrevving by? At what point is it overrevving? Out of the hole, midrange, or top end? If you tell me what you got I can get you going in the right direction. Adding weight will have the same effect as putting in a lighter primary spring. Chances are if you put in a lighter primary spring you will have to adjust the rivets in the weights anyway.
Lets say that after 100 meters (about 300 feet) it revs to 9000.
What sled do you have & what is your exact clutching set up..& I mean be exact...rivets, spring; helix; everything.
I'll have to look into the rivet thing this weekend.
I know it has 21/40 gearing, green sec spring at 70 degrees, 43 degree helix. YWY spring in primary, stock weights, probably the rivets it came with in the box. Probably box stock rollers too. I don't remember what the stock weights are called, but I recall from the shop book for this sled that the rivets in the weights were for high altitude. It has also been jetted as lean as 141,3 X 2 and 142,5. It has a hauck headgasket, reednotch mod and 47,5 pilots with the fuel screw turned out 1 turn from slightly seated.
0-1000 ft riding altitude. Temps down to -20c, but I'm not going to pin the throttle then.
I'm going to put in the heaviest rivets I can find in both holes, but what do I do if that isn't enough? I cannot gear up or use a steeper helix because the sled is also used for towing sleighs. Thanks.
I know it has 21/40 gearing, green sec spring at 70 degrees, 43 degree helix. YWY spring in primary, stock weights, probably the rivets it came with in the box. Probably box stock rollers too. I don't remember what the stock weights are called, but I recall from the shop book for this sled that the rivets in the weights were for high altitude. It has also been jetted as lean as 141,3 X 2 and 142,5. It has a hauck headgasket, reednotch mod and 47,5 pilots with the fuel screw turned out 1 turn from slightly seated.
0-1000 ft riding altitude. Temps down to -20c, but I'm not going to pin the throttle then.
I'm going to put in the heaviest rivets I can find in both holes, but what do I do if that isn't enough? I cannot gear up or use a steeper helix because the sled is also used for towing sleighs. Thanks.
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