Originally Posted by
PTP Racing
Have you tried everything and completely eliminated anything but the engine itself from being the problem? ie. replace fuel line, tank, exhaust couplers, glow plug. Have you thoroughly inspected it for air leaks? Does it have a zip tie on the carb boot?
Also does the engine run or does it stall constantly? You said its constantly rich or lean. Does it do it randomly? Are you tuning it and it goes right from one extreme to the other.
My first V-Spec I bought used. I got it in the winter and was running indoors on a small track and it ran perfectly. Then when I went outdoors to bigger tracks it seemed to be too lean but as soon as I richened the high speed even a hair it would fall right on its face. The problem turned out to be the midrange needle being set wrong. It was flush but about 4 oclock moving it to 2 oclock totally changed the engine. I was then able to lean the top end considerably and the engine powerband was much more linear.
I have to agree with isolating the problem if you haven't done so already. I'd even go as far as find someone you trust with the same vehicle if possible and ask them to hook up your motor to their vehicle and run it. I'd also return the carb settings back to stock and try and run it. I've seen a couple of people have issues with the fuel tanks and try to tune around only to really mess up the carb settings. If there is something wrong in the fuel delivery system, it can really throw you off base as far as trying to find the right tune. Also, check your exhaust pressure line too. Sometimes the pressure nipple on the exhaust pipe can get clogged with oil/dirt and that will affect the level of pressure the tank gets. Good luck and let us know if you were able to figure it out. It takes time, but once you do it once you'll be able to solve it again more easily next time something like this happens.