Rpm drop from 8500 to 7500

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ViperBite20

New member
Joined
Dec 9, 2012
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18
Location
Stevens Point, WI
02 sx viper non er model.
New oem stator and coil pack.
Cleaned clutches and tried different belts
Cleaned carbs idles good runs good but at wot it will sometimes pull 8500rpm to 100+mph. Other times it runs 8500 then drops to 7000-7500 or maxes out at 7500 from the start.
Any ideas?
 

powervalve clean and adjust and see what the belt width is, a worn belt will lower rpm as well. new the belts are 34.5mm wide, check yours.
 
ViperBite20 said:
02 sx viper non er model.
New oem stator and coil pack.
Cleaned clutches and tried different belts
Cleaned carbs idles good runs good but at wot it will sometimes pull 8500rpm to 100+mph. Other times it runs 8500 then drops to 7000-7500 or maxes out at 7500 from the start.
Any ideas?
Click to expand...

I have seen sleds with broken motor mounts having an erratic full throttle RPM like you are experiencing.

A weak or broken secondary spring or a polished or wet secondary sheave surface can cause the belt to be puled down too deep in the secondary putting the clutches in to high of ratio as well.
 
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I pulled power valves and cleaned them and the ports very well. Still same thing even readjusted them again to make sure they where right. I'm thinking it's clutch related
 
It's got a hauck helix and green and orange spring in hole 6 I believe. Buddy's sled that he bought like this ran great till this year. Could it be shifting out too soon and need the spring wrapped tighter?
 
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I had this happen on my viper a couple years ago. I could barely get it up to speed and once in a while it would rip like it was supposed to. All I had on hand was a new green dot secondary spring and a new 51/43 helix so I swapped to see what would happen. It was good to go. Not sure if it was the spring wore out or the bushing in the helix but it was definitely one of the two. Not sure how old or used the parts you have but it could be the same issue. I would try a new secondary spring.
 
Would you have a part number for the green spring?
Idk what kind of spring is in there now the whole thing is green and has a patch of orange that looks like someone did with a spray can
 
Finally heard back from hauck apparently it's a straight 49 helix and recommend stock spring or their silver spring.

Stock spring would be a red one correct?
 
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ViperBite20 said:
Finally heard back from hauck apparently it's a straight 49 helix and recommend stock spring or their silver spring.

Stock spring would be a red one correct?
Click to expand...
Yes. Stock is red.
Its actually black with a red stripe. part # 90508-536A9
 
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