akvector
TY 4 Stroke Junkie
I am starting a new thread in hopes to get more opinions. I am certainly not a guru and am learning as I go. I am not set up to do grinding etc... I am only using what is published for weights.
I am running 89A10's which are 47.5 grams it had short alluminum rivet in heal which .8 grams and the 2.7 gram steel rivet in the tip after my new header and air box lid I am over reving by how much I am unsure as the rev limiter kept me from getting there. I also had the 15.6 rollers.
I changed the heal to a 3.1 gram rivet and changed rollers to 14.5. Still over reving although the shift on the bottom is much smoother but still hitting 9200 plus. I am correct to assume the overall weight does not matter as much as the weight in tip itself?
I think I could still benefit from a heavier rivet in the heal of the 3.6 and where should I go on the tip? 3.1 will it bring the final rpms down enough. I thought a different helix was in order but after adding more weight to heal I think they are shifting together much better.
Any suggestions would be greatly appreciated.
Thank you
I am running 89A10's which are 47.5 grams it had short alluminum rivet in heal which .8 grams and the 2.7 gram steel rivet in the tip after my new header and air box lid I am over reving by how much I am unsure as the rev limiter kept me from getting there. I also had the 15.6 rollers.
I changed the heal to a 3.1 gram rivet and changed rollers to 14.5. Still over reving although the shift on the bottom is much smoother but still hitting 9200 plus. I am correct to assume the overall weight does not matter as much as the weight in tip itself?
I think I could still benefit from a heavier rivet in the heal of the 3.6 and where should I go on the tip? 3.1 will it bring the final rpms down enough. I thought a different helix was in order but after adding more weight to heal I think they are shifting together much better.
Any suggestions would be greatly appreciated.
Thank you
Mtnviper
TY 4 Stroke Master
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I think your on the right track. Generally speaking the heel weight controls the shift rpm at lower speeds while the tip weight have more effect at higher (shift out) speeds.
For example my XTX was over-reving (9200-rev limiter) at slower speeds while it would under-rev (8500) at 50mph and up.
The clutching chart shows to install light rivits in the heel and heavy rivits in the tip. What I did was swap the rivits from heel to tip with the same total mass as before. Now the rpm is 8900-9000 (sled has a header) through out the shift or what I like to refer to as a straight shift out.
If your still hitting 9200 on the bottom end, I would try 4.5 in the heel then see where your at on the upper end rpm wise. Depending on the weight profile, total weight mass will usually effect the shift rpm through out the shift.
You can also change primary springs to straighten a shift also, although I've had the best luck moving rivits. When I've reach the tuning limit with the rivits, then I'll move on to springs. But it's much easier/cheaper to stock rivits, then have a tool box full of springs!
The secondary will effect rpm as well, however you always want to tune shift rpm in the primary clutch. Then tune your desired upshift/backshift characteristics with the secondary. If you try to tune the shift rpm with the secondary clutch overall clutch efficiency may be reduced.
For example my XTX was over-reving (9200-rev limiter) at slower speeds while it would under-rev (8500) at 50mph and up.
The clutching chart shows to install light rivits in the heel and heavy rivits in the tip. What I did was swap the rivits from heel to tip with the same total mass as before. Now the rpm is 8900-9000 (sled has a header) through out the shift or what I like to refer to as a straight shift out.
If your still hitting 9200 on the bottom end, I would try 4.5 in the heel then see where your at on the upper end rpm wise. Depending on the weight profile, total weight mass will usually effect the shift rpm through out the shift.
You can also change primary springs to straighten a shift also, although I've had the best luck moving rivits. When I've reach the tuning limit with the rivits, then I'll move on to springs. But it's much easier/cheaper to stock rivits, then have a tool box full of springs!
The secondary will effect rpm as well, however you always want to tune shift rpm in the primary clutch. Then tune your desired upshift/backshift characteristics with the secondary. If you try to tune the shift rpm with the secondary clutch overall clutch efficiency may be reduced.
akvector
TY 4 Stroke Junkie
Thank you for the reply I will try loading another weight. And see what that brings. Any idea how much more weight to get the rpms down? Or am i at a try and see point?
Mtnviper
TY 4 Stroke Master
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Normally 1 gram will change the rpm by 100-200 rpm depending on the profile and if the change is added to the heel or tip.
Usually the rpm change will be greater when mass is added or subtracted from the tip. Because of the increased distance from the pivot point of the weight and increased parasitic horsepower loss that occurs at higher speeds.
Bill
Usually the rpm change will be greater when mass is added or subtracted from the tip. Because of the increased distance from the pivot point of the weight and increased parasitic horsepower loss that occurs at higher speeds.
Bill
hugger70mtnmax
Expert
Where you don't know exactly how high you are I would go on the big side. It may pull the rpm down a little bit low but at least you know where you are at then. I like to make a big change then you get a better idea on the effect of what you did.
akvector
TY 4 Stroke Junkie
Thank you for the replies I actually dropped a bit of weight in heel and added to the tip. If i stay with the same helix I will need to add a bit to the heel but I think a more aggressive helix would make it right.
