Mt cat zr HELP

[pstock800]

I have a mt cat 500 it has a 162 track with 7 tooth wahl driver. I am having a hard time getting any top end out of it revs up 8400rpm and only goes 50 60 mph i know that the 7 tooth isnt helping. it has a 20 t 39 bottom gear, it rides like a 440 sno pro good power on the bottom but no speed .

Any ideas, please dont say get a bigger motor the one i have goes good.

not sure if i put more weight in the clutch to load the motor if that will help
i am going to change the secondary helix and spring today back to stock.

 

[XR-tech]

It seems like a LOT of track for a 500. My 500 has a 136x2. It does pretty well, but doesn't have nearly the top end that a 121 does.
I'm running stock ZR500 weights and a 53degree helix with yellow secondary spring

 

[pstock800]

500

well tonight i figured it out i reworked the clutchs. 53 helix back to the red/white spring 52 gram weights. it rips now i can stay with my buddys rev 800 , it really goes like hell for a 500, 100mph down the lake no problem and pulls hard. and its only a 500 go figure. turning 8400 rpms