Clinician
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Post by tjmaupin520 on Jul 20, 2017 15:29:22 GMT -6
Just bought my son a 2017 taotao CY50 and after breakin we started doing some mods. This thing was so lean stock that removing the air box snorkel made it bog out and die under any load whatsoever. So new carb was first thing. 19mm carb came with a 78 main jet. Ran ok. Got much better rpm and low end power. Took off the air box and lost top end.. So figured it was rich, sparkplug confirmed. We are down to a 72 main jet now with no air box (cone filter) to achieve any power whatsoever... Any advice appreciated.
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Clinician
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Post by tjmaupin520 on Jul 21, 2017 14:25:15 GMT -6
Update I pulled stock carb apart and found it has a 75 main jet. What confused me most is no matter what we do it still seems to run best (top end anyway) at stock settings with the air box. Cone air filter seems to rob power no matter jet size. No restriction in exhaust manifold. Only two places I can figure it's getting held up. Stock exhaust outlet is much smaller than inlet. And the inner diameter of the intake manifold is 1mm smaller than the current carb. Any thoughts.
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Clinician
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Post by greginisn on Jul 23, 2017 0:45:34 GMT -6
The 49cc people seem to think the QMBs run better with std intake & exhaust. Unless you have made major engine mods, bbk, stroker crank hot cam kinds of things. Many people run an 82 to 85 main jet and alls well.
Good Luck.
Greg
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Clinician
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Post by tjmaupin520 on Jul 23, 2017 18:43:29 GMT -6
Thank you so much. Rejetting to 85 for now and seems to offer the best acceleration which is the primary need around town. BBK next step. Have 47mm ready to go however was told it would be best to leave stock until he gets a little more confident and the bike is broken in a little. Scoots are new to me, my ride is a bored out vl1500 but my son doesn't want to get a license so the 50 is his limit for now.
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Post by lostforawhile on Jul 23, 2017 21:10:13 GMT -6
it's awful trying to tune one of these carbs with an open filter, it's supposed to be only 2 cycles that are so critical about the air cleaner, but the 4 cycles seem to be as well, it's probably got something to do with air velocity, and the valve. with the long intake tube, valve opening and closing could be setting up tuned pulses to help with airflow
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