Engine Trouble need advice on 66cc bog at high rpms

jonathan62019

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3:41 PM
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Jul 11, 2015
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Kansas city, Mo
my first post. i might be all over the place sorry in advanced.. ok so i got this bike used. put it all back together, started up great runs great at idle and even WOT until it gets to a certain RPM then it just bogs out, even if i give just a little gas. i thought i was running lean, so i checked for air leaks. found i was leaking air through the intake manifold.(would only run when choked) so fixed that air leak. no need to choke it now to run. idles smooth. has good power until that rpm gets a little high, its not starting at a real high RPM either i dont have a tach but id say 3/4 of what it should be doing. i moved the clip up a few notches each time it didnt fix the problem.. just messed with the lower end of the rpms. cleaned carb and jet all that good stuff. ....

so this is where i am now. thanks for still reading if you are. this is my real question and situation,... i was running around right under the RPM where is starts to bog when all of a sudden i have a lot of power and this thing starts to move. hit about 35 mph i was moving and no BOG! i went to turn down my street and slowed down and it was running really bad now, i looked down and my intake manifold was broken... moved the choke up a little bit to keep it running and babied it home. SO any suggestions? am i starving for air at those high RPMS? or what? i dont know if the intake manifold broke before or during the burst of awesome power haha. the new intake manifold is in the mail so i cant ride it yet, any advice or feedback would be great. thanks for reading :)
 
could be you need a lower float level or smaller main jet
 
Yeah I was thinking of just buying a new carb when i ordered the 40mm intake manifold. They are so cheap. I'm shocked how cool these engines run. I figured I couldn't touch the head after an hour ride. But I can put my hand on it for 4 seconds before I go OUCH!.
 
Put in an NGK 5944 (BPR7HIX) Iridium plug and a better air cleaner on.
 
i had a NGK 5944 in it when i got it. i switched in a bosch platinum 2 and it didnt change anything. when i get the manifold in i will most def check into the air cleaner. it looked pretty bad. most likely going to just fab up a better set up. from what i have been reading. i think i might have been 4 stroking at the point of the bog down. so now i know where to start looking for answers. ( new to 2 stroke engines.)
 
new manifold is out for delivery from local post office.. wow bikeberry outlet on ebay has some super fast delivery. i just ordered it Saturday. pretty excited.
 
Put in an NGK 5944 (BPR7HIX) Iridium plug and a better air cleaner on.
BPR 6 HIX

If you live anywhere where its hotter than 80 degrees and less than 1000 ft above sea level.

The 7 Was running too rich for me. Then it looks like its running to lean. Idkwtf.

I Have my fuel mix at roughly 32:1
 
BPR 6 HIX

If you live anywhere where its hotter than 80 degrees and less than 1000 ft above sea level.

The 7 Was running too rich for me. Then it looks like its running to lean. Idkwtf.

I Have my fuel mix at roughly 32:1
The higher the number, the cooler your engine runs.
Too cold and you foul plugs.
Too hot and well, anything can happen.

The coldest (highest number) you can run without fouling is best but your carb plays a big part in this too.
 
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