Overrev first 20'

SX600abuser

SX600abuser

Member
Joined
Jan 22, 2010
Messages
193
Location
Holland, MI
I am in the process of dialing in my clutching for my new motor. It is currently launching at 8400rpm then dropping to about 7700rpm within the first 20-30ft. I am planning to lighten my weights that are currently at about 48.7grams. I believe the overrev is being caused by too much preload on the secondary. I am running a 43/51 helix with a green spring at 70* wrap. I think if I take it down to 60* wrap it will much reduce my overrev, then I can deal with getting the weights right for the shifting RPM. These are my assumptions, I am looking for thoughts on this, just to help me know I am on the right track, or if I am thinking incorrectly.
 
make sure its not slipping the belt.is it a yamaha 51-43.i had an aftermarket helix that was drilled wrong and at 60 wrap it would slip the belt .did the over rev at first than pulled tach back/
 
tedgoesfast said:
make sure its not slipping the belt.is it a yamaha 51-43.i had an aftermarket helix that was drilled wrong and at 60 wrap it would slip the belt .did the over rev at first than pulled tach back/
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Yeah, its a yamaha helix. The belt is clean and almost brand new. The clutches are clean. It is not slipping. Yes, it would over rev then once it felt like it was starting to shift it would drop quickly to 7700RPM and stay steady there.
 
bluemonster1 said:
overshifting??? Like going from 1st gear into 3rd..drops rpms quick.
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Thats a good question, but I don't think it is it because once it settles down to 7700rpm it stays there the rest of the time. I guess maybe it could still be overshifting too much. Maybe I will try to add more wrap if it doesn't go away at 60*.
 
also could be binding clutch's also.Had that happen to me and had to replace the bushings..Main thing is to make sure the setup is totally stock setup for that year and run it and see what happens.If it still acts up with stock setup..then you have some clutching issues for sure.Also what are the gears in it now and what size track does it have on it..
 
bluemonster1 said:
also could be binding clutch's also.Had that happen to me and had to replace the bushings..Main thing is to make sure the setup is totally stock setup for that year and run it and see what happens.If it still acts up with stock setup..then you have some clutching issues for sure.Also what are the gears in it now and what size track does it have on it..
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It has 21/40 gearing in it. Clutch bushings are all in good shape. This sled has been changed too much to run a stock setting...lol It has a 121" track for now, 9 tooth drivers.
 
i had 2 similar overrev issues on my sled,first time,seperated motor mount
backside closest to the secondary,pulling away from a stop the motor would rock forward and the belt would pull the secondary apart way too soon.
second time put on a new yamaha belt,same symptom,did some research on here and found out about the three little shims under the bolts on the back of the secondary,that i now call the "new belt shims"
the wider belt was pulling the secondary open too soon,removed the shims and it went away.
 
SX600abuser said:
I am in the process of dialing in my clutching for my new motor. It is currently launching at 8400rpm then dropping to about 7700rpm within the first 20-30ft. I am planning to lighten my weights that are currently at about 48.7grams. I believe the overrev is being caused by too much preload on the secondary. I am running a 43/51 helix with a green spring at 70* wrap. I think if I take it down to 60* wrap it will much reduce my overrev, then I can deal with getting the weights right for the shifting RPM. These are my assumptions, I am looking for thoughts on this, just to help me know I am on the right track, or if I am thinking incorrectly.
Click to expand...
if this sled is your 600 triple then you should be reving 8500 rpm . i would try less weight in the tip of your weights first . what weights and rivits do you have in it now?
 
9801srx said:
if this sled is your 600 triple then you should be reving 8500 rpm . i would try less weight in the tip of your weights first . what weights and rivits do you have in it now?
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Dude, this thing is a frankenstein sled at this point...lol I put 700 cylinders on it that are trail ported. It currently has 8AB weights in it, they weigh currently 47.3 grams. I have ground the weights down quite a bit so I am unsure what they weigh individually anymore.

I decided to just try the red spring in the secondary today. Problem solved. So it must have been holding out too long before it started to shift. Lightened the weights to the number above and it is sitting at 8200-8300rpm. Ready for snow. Thanks for all your input to help me figure this bad boy out.
 
SX600abuser said:
Dude, this thing is a frankenstein sled at this point...lol I put 700 cylinders on it that are trail ported. It currently has 8AB weights in it, they weigh currently 47.3 grams. I have ground the weights down quite a bit so I am unsure what they weigh individually anymore.

I decided to just try the red spring in the secondary today. Problem solved. So it must have been holding out too long before it started to shift. Lightened the weights to the number above and it is sitting at 8200-8300rpm. Ready for snow. Thanks for all your input to help me figure this bad boy out.
Click to expand...
nothing wrong with a frankensled .lol my srx is one to, somthing like a yamapolcat lol. good to here ya got it figured out.
 
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