90 zx400r-H carb help - running VERY rich
Posted: Mon May 23, 2016 7:34 pm
Hi everybody.. go my project bike going weeks ago - struggling my butt off to get it to run well.. i made some rubbers for the intake manifolds (what a terrible design imo)..
Anyway - bike is running VERY rich no matter what I do.. im having a hard time getting the float height correct (using the clear tube method).. manual says 8mm from mark - but my image quality is so poor i cant really make out where, it looks like the split of the carb - regular measurement is 11mm - however, one or two of me needles seem to have a tiny bit more spring to them - so im trying to get it right via the drain / tube method..
Manual main jet calls for 98 standard, mine has 102 jets in (got it like this).. when I had head off there wasnt too much show of carbon build up - valves had a laer on their faces, thats about it..
pulled carbs a few times now - tried between 1 1/2 - 2 1/2 turns out - is it possible i have some air jet blocked or something? I have cleaned these things out a few times now - when i spray on of the front holes, the 3 at the other end of the carb spray solid carb cleaner.. ive cleaned the pilots, mains and completely removed needles etc.. emulsion tubes still look good (perfectly round)..
I cleaned exhaust and did a 100 mile run at 8-10k rpms.. it was powdery black again when i stopped, meaning this seems more ofa mid-upper rpm issue, that would be the mains yes?
going to drill out some brass m5 bolts to 1mm and see if it improves while i order some 98s from china (if it doesnt!)..
fyi - at sea level..would 2 jet sizes make such a difference? even plugs are dry and sooty - and choke def not stuck.. (i checked)
Anyway - bike is running VERY rich no matter what I do.. im having a hard time getting the float height correct (using the clear tube method).. manual says 8mm from mark - but my image quality is so poor i cant really make out where, it looks like the split of the carb - regular measurement is 11mm - however, one or two of me needles seem to have a tiny bit more spring to them - so im trying to get it right via the drain / tube method..
Manual main jet calls for 98 standard, mine has 102 jets in (got it like this).. when I had head off there wasnt too much show of carbon build up - valves had a laer on their faces, thats about it..
pulled carbs a few times now - tried between 1 1/2 - 2 1/2 turns out - is it possible i have some air jet blocked or something? I have cleaned these things out a few times now - when i spray on of the front holes, the 3 at the other end of the carb spray solid carb cleaner.. ive cleaned the pilots, mains and completely removed needles etc.. emulsion tubes still look good (perfectly round)..
I cleaned exhaust and did a 100 mile run at 8-10k rpms.. it was powdery black again when i stopped, meaning this seems more ofa mid-upper rpm issue, that would be the mains yes?
going to drill out some brass m5 bolts to 1mm and see if it improves while i order some 98s from china (if it doesnt!)..
fyi - at sea level..would 2 jet sizes make such a difference? even plugs are dry and sooty - and choke def not stuck.. (i checked)