Tuning up a Bing 18mm

DanielMaia

DanielMaia

New Member
Hi Norman,

Im trying to tuning up a bing 18mm on my 60cc.

It has a main jet size #75, and some symptoms:

- I have to accelerate very soft. If i push WOT she hesitates, boggs, she slow down, i close a bit the accelerator, and it revvs good

What you think?
 
sorry I haven't messed with a bing carb but they should work like any other. larger jet to richen it smaller jet to lean.for wide open
drop the needle to lean raise the needle to go rich low to mid range on throttle
plug checks will help.
try to richen it a little if it get worse then you should try a little leaner.
or try a little choke if it will then pick up good through out the rpms with a little choke on then you know it needs more or a richer mixture/bigger size jet and maybe a change in the needle.
I don't know if this carb has adjustable air bleeds or idle circuits. If it does then you will probably want to mess with them.
 
Thanks Norman,

Yes, this carb has 2 screws. One is the idle screw, and in the opposite side has a adjustable screw, i think its the air screw, and i dont know very well if i need to close or open it..

Right now its with a #85 gigleur, and its 4 stroking a lot in high rpms (WOT), and i'll try a leaner jet, like #80, and see how she reacts.
 
Now im near the optimal misture settings, it revs slightly better, but if i push too fast the throttle it boogs...and i need to push throttle back, and it revs like crazy..what i need to do to correct this symptom?

Other thing: as i said, this engine has port matching in the transfers, the exhaust was raised a little notch, and it was all polished. Low end and mid range it has a good power, but in high rpms its very weak, i dont know why...any guess?
 
I think Norms gonna wanna know what color a fresh plug looks like. Meaning after ran for a while the color of the plug tells us a lot. If the color of the plug you have now is black that means too rich. A nice chocolate brown is right.
 
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