I HAVE A 99' SCRAMBLER 400. THE BIKE WILL SPIN THE TIRES IN REVERSE ON PAVEMENT BUT IN FORWARD THE BIKE HESITATES WHEN THE THROTTLE IS PEGGED AND AFTER IT REACHED 5 mph OR SO IT TAKES OFF LIKE IT ALWAYS HAS. DOES ANYONE HAVE ANY IDEA WHAT WOULD CAUSE THIS? IT SEEMS LIKE AN INTERNAL GEARING PROBLEM OR POSSIBLY A BAD CLUTCH SPRING BUT I REPLACED BOTH OF THE CLUTCH SPRINGS AS WELL AND HAVE NOT HAD ANY IMPROVEMENT. I HAVE BEEN TROUBLE SHOOTING THE BIKE FOR OVER A WEEK. OVER THE WEEKEND I DRAINED THE FUEL, REPLACED THE FUEL FILTER AND CHECKED THE VENT LINES. I HAVE ALSO CHECKED THE CARBURETOR, REEDS, AIR FILTER, COMPRESSION AND SPARK PLUGS. EVERYTHING IS CHECKING OUT OK.

 

WOLP, where is your belt sitting in the secondary clutch at rest. Above the sheave, flush, or below the sheave. It whould be at least flush, or a sixteenth of an inch over. If it is below you are losing a little bit of low gear ratio. I had this problem on an 800 Storm snowmobile. It would really bog if you didn't keep the belt up in the secondary.

 

I BELIEVE THE BELT IS RESTING SLIGHTLY ABOVE THE SECONDARY CLUTCH SHEEVE. I HAVE A NEW TOP COG PRO BELT THAT I PUT ON ABOUT 2 MONTHS AGO. IT DOESN'T SHOW ANY SIGNS OF WEAR. IF THE BELT IS RIDING BELOW THE TOP OF THE SHEEVES IS THERE ANY WAY TO DECREASE THE GAP BETWEEN THE SHEEVES SO THAT IT WILL RIDE HIGHER. I ONLY HAVE ONE SHIM SEPERATING THE SHEEVES NOW. ALSO, BELT DEFLECTION DOES SEEM A LITTLE EXCESSIVE, HOW CAN I INCREASE THE DISTANCE BETWEEN THE TWO PULLEYS?

 

Isn't this how an unmodified clutch works? My TB before the spring never took of hard. It would just putt off then it would kick in..

 

I had a similar problem after I installed my roller clutch and a new belt. I thought I had plenty of breakin time on the belt. I called Aaen and he suggested that I sand(rough up) the sheaves. I did and it made a world of difference.

 

My 98 scrambler ran the same way. I put a polaris purple spring in the primary and tightened the secondary to 17lbs preload. Realy helped on the bottom.

 

Thanks for the advice. Do you remember what grit sandpaper you used and about how far down the sheeves you sanded?