spitting fuel

[7m-iata]

So I used the SEARCH function and found a bunch of instances of peoples scoots spitting fuel at idle when a reed is bad. I've noticed my scoot does this but not at idle instead at high rpms and it does it REALLY BAD, the idea that my reeds are closing to slowly pops into my head, and I've been having ALOT of trouble getting it tuned, it runs RICH down low at wot (4 stroking) ok at 1/2 to 3/4 but up top high rpms it goes REALLY lean. I'd imagine this is because half the fuel is just being spit out of the carb rather than entering the cyl. I get a great crisp idle no starting problems or anything like that that would be the normal sign of bad reeds. Good seal on them filled the reed cage with some 2T oil and got very little to no leaks. Would a set of CF reeds close faster, or can I get a high tension set? I'm alright with losing some low end but I NEED the top speed around town where ALL the speed limits are 40+.

1e40qmb 72cc big bore with off brand pipe. stock 17mm mikuni carb autolite 275 plug stock gears/rollers/springs. 32:1 premium (93) and castor 927

[bakaracer]

For one the autolite is the wrong plug to use. Yes even though the cross reference shows that's the same, its not. Either a nippon denso or ngk plug is what you should be using in a 8 or 9 heat range. Get the right plug first then mess with the jetting. A different heat range plug will change the jetting.

[7m-iata]

I was running the ngk bp8hs and the local scooter shop told me the autolite is better hes been in business a while and they had a ton of scoots with bbk and stuff there so I trusted him /: runs the same I'll throw the ngk back in it I guess lol. still doesn't help with my issue either way, I'm not jetted lean I'm just losing so much fuel out of the front of the carb that it goes lean. I CAN NOT go any richer I'm already 4 stroking from 1-15mph anywhere above 1/2 throttle with my fuel pin at its lowest setting.

[bakaracer]

There is going to be some fuel spitting going on out the carb. At wot the reed doesn't shut because the piston becomes the reed after a certain point. What kind of reed is in there now? As for your jetting goes, if after 3/4 throttle id lean then up the main. You will have to lean the pilot or needle

[7m-iata]

I know SOME is normal, but theres a VERY large quantity coming from it you can see full size almost rain drop size drips shooting from the carb and dripping down my freshly painted frame and I STILL get a LEAN plug chop on both the NGK and autolite plug):< I have the stock metal reeds they only have about 20 miles on them.

[bakaracer]

Change those reeds out. They are notorious for breaking when a bbk is used and causing engine damage. I wouldn't be surprised if they are already cracked. Switch to a carbon fiber one or fiber glass one.

[7m-iata]

I looked at the fiber glass reeds and they seemed really weak and flimsy /: probably order a set of cf ones soon. No cracks in the stockers though I had the reed cage out earlier today checkig them when I noticed how much fuel was shooting out. If I were actually using the amount of fuel being shot from my carb I would probably be fouling plugs up top... Is there anything else that could cause excessive crankcase pressure besides bad rings? I have good compression and only about 150 miles on my rings very little piston slop or is my most likely problem just he reeds not operating to the right extent?

Thanks for the help and sorry for so many questions, making the transition from 4 stroke full size engines efi and turbos and my 4T 4 wheeler to the world of 2T performance is not going the smoothest for me lol

[bakaracer]

Check the float level and make sure its within spec. If its a stock csrb from another bike, you need to find out what the carb specs are

[Wheelman-111]

Greetings:

Metal reeds are heavier. Momentum prevents them from closing quick enough at higher midrange RPM. CARBONs are light, snappy but can be brittle and fail quickly. CT manis use glass, last forever and may solve this.

[7m-iata]

Its the stock Carb from the 1e40qmb and the float is right at spec. Thanks for the info