having trouble tuning gx340 clone with 32mm mikuni carb.

[jetasen74]

i have a gx340 clone with bigger exhuast and it seemed under powered for an 11 hp.(the stock jet was an 88) so i bought a 32mm mikuni that i was told it would go right on and run great. it had a 35 pilot and a 160 main and it ran fast mid to top range but cut out when i try to floor it.and it is way to rich and keeps fouling plugs. i droped it down to a 100 main but it run like crud and it was still rich. please help!

[jetasen74]

i got a reply from were i bought the carb and he said others run it strait outa the box or end up with a 35 pilot and 200 main. i did and it ran fast but cut out when ya floor it. and the plug read rich. could my exhuast be to big or a bad coil?

[jetasen74]

i had a good size pilot and 200 main and it ran really good and strong for a good hour and all of the sudden it died and would not start. got it home put a plug in and it started right up. whats the dealio?

[jetasen74]

what happens when alot of oil comes out the valve cover vent?

[BuggyMaster]

What did the plug look like when you pulled it out? Was it fouled black?

[jetasen74]

ya it was pretty black. i did however clean the heck out of the carb put back in the recomended 35 pilot and 200 main, it runs pretty good but still cuts out when ya try to floor it. havnt done a plug check cause i ran out. i got some more and will do a plug reading today. i think my valve cover vent was plugged. also when plugs are fouled like that can they be cleaned and use again?
also i had to adjust float level yesterday cause it was overflowin could that have been the culprit?

[speedshopmike]

jet, check the oil level - and smell it.
if the carb was flooding it probly added quite a bit of gas to your crankcase, raising oil level, causing it to puke up.
the float level setting really shouldnt change while driving.
that high float level will make it run very rich and could be the problem for day one.

[jetasen74]

thanks i will check da oil. drove it a little to day after adjusting float and putting in da 35 pilot 200 main. it started right up and run great,still cuts out on hard accel from a stop but i will deal with it until i get a little bigger pilot.

[jetasen74]

i checked da oil and low and beholed lots of gas in the oil. i also had to move the air filter cause it was getting realy muddy. and added a tool box. pics of filter on other thread

[ckau]

IMO, that carb is too big for your application. a 32mm needs a intake/ exhaust tract of very large perportions to handle the flow. A 30mm or larger intake, head with 24 to 28mm valves and an exhaust of 1" min. inside dims and a lsrge volume air filter. This carbs flows a bunch of volume. if the tract can't handle it. you have the problems experienced.
The excessive blow by at the head vent and fuel in the oil indicates raw fuel dumpimg into the cylinder.
Don't assume this carb is a "plug an play" thing. Do the research, plenty of stuff around about this carb. check float settings, Slide needle position air and idle position screws.The jetting seems way too much. If anything, go down on main jet size until you get a lean condition then adjust from there

[jetasen74]

my problem was the float level, it was way off.i do have the big inthake and 1-1/4 exhaust, its running great now except the hard accel. it cuts out, just need a bigger pilot. i did research and i was told these carbs work great on my motor. i dont have a lot of mula so i research all my purcheses. i put a big pilot like a 60 in it and it ran like a bat out of hell,this was before i adjusted the float level. it has the recomended 35 pilot and 200 main in it now.
if i ran good with that big pilot, i may try it again now that i adjusted the float, cause man it was fast and had some balls to go with it.

[jetasen74]

where can i get a big bore kit for a gx340?