I have a 99 Scrambler 400 4X4 with a lot of mods, almost all from RCR, including head work, porting,
flywheel reduction, carb bore, clutch work, etc.
I seized a piston while riding in Utah over the summer (before Ritter work) and have been gun shy regarding running lean ever since. I have been running a 320 main with much success but I think I am running my oil too rich. I left the oil injection hooked up and still pre-mix 40:1. I notice when I punch the throttle I cannot get the front end up as I did before. However once the engine builds revs the midrange is incredible and top end better than stock. I have been focusing on the low end and midrange. Now to the question...Can running the oil at too rich a ratio cause a decrease in power.

 

I have a 95 400 Scrambler with RCR mods. Rick suggested 32:1 mix of Klotz (R50) with a 310 main. I can't keep the front end down. My mods include bored carb, reed spacer, shaved head, wiseco .040 over, RCR trail port, HPD pipe and silencer, HPD aggressive helix and springs(brown and violet), reed spacer, oil injection eliminator from Hot Seat. My previous experience with a Tri-Z indicated that a richer oil mixture has more lubricating qualities, but also leans out the motor when using pre-mix. The addtitional oil volume displaces what would have been gas. RCR knows what they're doing. I'm VERY hard on my quad and have no engine probs since the conversion to premix.