Running to LEAN

I have two GRC bikes that have a big problem with them. Went racing looked at the plug and it was lean. Kept changing the jet until I was out of big numbers and the plug was white as hell. I ran a jet ten sizes bigger than what my friend had which was the exact same motor done by scott finlay. His was fine but mine was not. can someone help me figure out why my bike is so lean. I was running a 18 in my 40 and 17.5 in the 50

wel whats your fuel/oil ratio and what octane and oil are u using?

I am using ams oil mixed 50:1 and its 91 octane

it might be a air leak but im not sure how does it idel? ect

yeah, u can try running 32:1 instead of 50:1. that might help

32 will make it leaner as the oil replaces the fuel.. Pocket Racing Bikes email danny he knows alot about these bikes

definitely sounds like an air leak all things considered if the bikes are the same

BUT also remove the flywheel and observe the key. make sure its not been pushed out the back or the thing has sheared off. i had a situation in my bzm motor where it would backfire on throttle and another on the polini where it would just overheat way too fast and kill plugs (id pull them out perfectly clean as well)

so id check the flywheel key and if not that, go hunting for air leaks. idle stability like barnsey said should be a key indicator for that.

first of all - what carb jetting do you have and what is the actual motor setup? if you have the atomizer with the holes in it 266AN then you need a MASSIVE main jet. i have a 120 in one of my bikes to get it running right.

Your Chris from Edmonton right? If so shoot me a pm and you and I will get together and get the Grc up and running right. It's Joe with the DM. How long have you tried running? It does take a little bit for the plug color to change. You might try a new plug to find the right jetting.

hey Chris I left my number on your PM's. I'm leaving for Vancouver on holidays for 2 weeks starting Aug22 so call me before then and we can see if we can get her running right. I am literaly a 11/2 minute ride from Griesbach. I think your on the South Side right?? Anyways maybe your dad can drop you off...I work on the South Side too so let me know whats most convienant for you. Top fuel toys team rider

i figured it out. just put a new carb on.