fcr39 carb poppin at high speed

[vwman69]

I have an 03 suzuki with full alba exhaust k&n with lid removed hot cams and a fcr39 carb. The quad ran great for ever. I do almost all of my rideing at the coast (500 feet or less) I took it up in the mountains and when i started getting up pretty high it started to sputter on me which is no big deal since i didn't re-jet it. The problem is now it still sputters on me at full throttle and it gets worse as i get higher in the gears. I put a new plug in it pulled the carb and cleaned it but everything looked good and it is still sputtering even though I didn't change the jet do I need to re-jet it again? I just don't understand if it was good before why is it sputtering now or could it be a different problem. Oh yea I also checked the valves and they are all good any help would be appreiciated

[cataway]

Originally posted by vwman69
I have an 03 suzuki with full alba exhaust k&n with lid removed hot cams and a fcr39 carb. The quad ran great for ever. I do almost all of my rideing at the coast (500 feet or less) I took it up in the mountains and when i started getting up pretty high it started to sputter on me which is no big deal since i didn't re-jet it. The problem is now it still sputters on me at full throttle and it gets worse as i get higher in the gears. I put a new plug in it pulled the carb and cleaned it but everything looked good and it is still sputtering even though I didn't change the jet do I need to re-jet it again? I just don't understand if it was good before why is it sputtering now or could it be a different problem. Oh yea I also checked the valves and they are all good any help would be appreiciated do you mind saying what your jetting is ? when you say high up ,how high up ? 6000-7000ft ??

[vwman69]

I'm not sure about the jet size I can't remember I will try and check this weekend the altitude was prob. about 5000-6000 ft.

[vwman69]

The jet thats in there right now is a 175 and like I said it ran great before i took it up to the mountains.

[cataway]

you say you cleand the carb ,did you clean the vent hoses ?

[vwman69]

I checked the vent hoses and they are clean

[jonboy]

At higher altitudes, cold weather can really effect your jetting. If your are at Eugene, OR its only 571ft. But when you go up to the mountains you should try to find out the elevation. Google Noaa.gov and enter the city or town you'll be riding at and at the top left it will have your elevation. That should be what your jetting for. Thats a pretty drastic change from 571ft to 6000ft. So rejetting is in order.

[cataway]

a 175 is definitely to big, to big for sea level to ,165 should be better