red devil
New member
Just found out that I put a bender 53/35 helix on my slp piped viper everything stock weights are the same as factory setup. The sled did underrev when hitting the throttle 8400 rpm and would climb to 8700rpm forgot tomention wrapped secondary to 80# with stock spring. The sled did wake up after 60' or so and would pull like a son of a gun to the top speed which it seemed to add 6 mph. I was thinking of dropping some weight in primary but was wondering since I had the same springs in it for 5,000miles if I went new will I see rpm's jump up to where I want them? Just wondering what everyone else was running at 1500" elevation or maybe try some different spring combo's THANX IN ADVANCE 
A couple of things to try, to straighten out the shift would be a helix with less spread, say a 51-43. You can also move weight from the inner hole to the outer hole.
It would be a good idea to replace the primary spring, since it's been in there for 5000 miles. A soft spring will bring the rpm's down. Also it's best to tune the rpm's up or down using the primary.
It would be a good idea to replace the primary spring, since it's been in there for 5000 miles. A soft spring will bring the rpm's down. Also it's best to tune the rpm's up or down using the primary.
red devil
New member
Mtnviper are you the same guy that told me about a bender yelow red spring a little while back? If you are was thinking about that the other day with this helix, Like this helix alot and if I can do something with it out of hole might have something. I'm pipeped and peak rpm's are 8750 that I'm shooting for(slp's) Thanx for your help.Don't have my notes in front of me but that secondary spring was what I am thinking about with the fresh primary spring, THANX FOR YOUR HELP MTNVIPER!
red devil, it must have been some one else. I have never tried the Bender yellow red spring. 8750 should be right in there, depending on jetting. Mine (SLP also) runs strong at 8800. If I lean it out for drag racing (too lean for normal riding) then the power peak moves up 100-200 rpms.
On my sled with the SLP's, it seems to run stronger, with a shift spread of 100-200 rpms. Example start at 8700 and finish at 8800-8900.
The 8EK's can over-rev on the top end. I was able to straighten the shift by about 100 rpm. By moving rivit weight from the heel to the toe, with the same total amount of weight combined.
But the shift spread was still wider then I wanted. I ended up going with a different weight, with a flatter force curve (8CR's for mountain use) to straighten the shift.
For lower elevations 8DN-10's (used in Mountain Vipers and some SRX's) may work better. They have a flatter force curve then the 8EK's, which would allow you to load more weight in the heel if desired, and still maintain a desirable shift curve.
8CR 38.09 grams
8EK 39.00 grams
8DN-10 39.76 grams
On my sled with the SLP's, it seems to run stronger, with a shift spread of 100-200 rpms. Example start at 8700 and finish at 8800-8900.
The 8EK's can over-rev on the top end. I was able to straighten the shift by about 100 rpm. By moving rivit weight from the heel to the toe, with the same total amount of weight combined.
But the shift spread was still wider then I wanted. I ended up going with a different weight, with a flatter force curve (8CR's for mountain use) to straighten the shift.
For lower elevations 8DN-10's (used in Mountain Vipers and some SRX's) may work better. They have a flatter force curve then the 8EK's, which would allow you to load more weight in the heel if desired, and still maintain a desirable shift curve.
8CR 38.09 grams
8EK 39.00 grams
8DN-10 39.76 grams
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