I've been racing with the Colorado hill climbing assn, for the last two months. Heres my problem I'm running a 670 13to1 stage 3 cams 45mm mikuni 40mm intake and 35 exhaust ported polished rwr ign etc!
I'm using 114 trick racing fuel with the clip 2 to bottom and 150 main with half pumper at 8000feet+. I will cut out when I hold it at one rpm but it runs great up to the top end where it seems I haven't got any power to hit 80mph I can only get 73 out of it. but when i go and read the plugs there clean as a whisle so I jetted up to 155 and it ran like crap! I dont want to burn a hole in the piston. With this racing fuel it seems I cant read the plugs is that true??
I'm thinking of running VP mr8 or mr9 oxygened fuel will this help me much at this high alt? Just to point out both these fuels have lead in them too. I have thought of when the season is done I would go and get a another pami piston to run it up to 14to1.

I'm not getting bet too bad by the other racers just about 10-20sec in a 4min race. which are all banshees that are 500 strokers. I just need more top end I have step up one tooth in the front and I'm running 20.5 hoosiers.I've got them in the corners but they out run me in the straights there running 80 and I'm running 73-74. the course is dirt roads switch backs. One thing is that I'm over 100lb's more than them but I think it helps me in the corners mantaining my speed just need to go faster!!!!

Help me out guys There are only two Fourstrokes out there so there is no help from the two strokers.. ooo and by the way the other fourstroke is a polaris predator and I have smoked him every time!!

www.chcaracing.com
just for those that want to see what I do!!!

 

where do you have your air fuel mixture, i recomend 1-1/2 turns out.. it works better for me at high altitudes, and yes the 114 is very hard to read plugs with, i would keep an eye on temp and jet a tad leaner.

 

I think it's difficult to get correct jetting from plug color alone when running quality fuel, I think you end up being rich, if jetting up was not good time to go the other way, this seems to match with your lack of top end power, try leaner and watch the temp