So I brought in my Thundercat to the local dealer to get the clutches checked, cleaned, alined, and the primary spring was changed. The original problem was the maximum rpm at full whack was 7700-7900 rpm and the top end was not at 100 mph. The new spring got the machine to go 115-120 mph(as shown on the speedo), but the rpm is still at 7900-8100. The manual says to run it at 8300 rpm and when it was -25 C, it would run at 8200 rpm with noticabile power gain. Now I know the cold would make it run leaner with more power output, my concern here is should I change the spring again to a green one therefore uping the rpm to around 8300-8500 rpm and benefiting from more power output. The cat mechanic said to try it like that and suggested using a green spring to solve the problem if I was not happy at the performance.

Try tightening up the secondary spring one notch.

Rick.

I did that all ready and lost top end.

you should gain approx 200rpm by tightening your driven spring one notch,,,,that would bring you up to your 8300 rpm,,,,,,

Are you talking about the green spring in the secondary? What spring is in there now?

What manual says to run the 1000 at 8300? I have an 01 and it says to run it at 8500.

Is your tach calibrated?

To get the RPM back you could lighten the weights or buy a primary spring with more final load. What primary is in there now? About 20lbs in pressure is about 100 rpm.

dont run a heaver spring unless you want to go slower you need a helix with a less angle on fullshift stocks a 57/50 i think go to a 62-46 or 44 thatll fix it if the jets are to rich youll have a hard time gettin the revs also, best is like 8200 at the start and 8500 end of pull even with stock pipes