carb advice
 

Ok.. so my 88cc fiddy is sputtering and popping when i ease of the gas after nailing it - I'm told I might be running too lean...

next question, which screw to turn, and which way.

a pretty basic question I know, but I really have never done any work whatsoever to gas motors. I am a fast learner and intend to get this right myself.

any help you can offer is much appreciated, specifically,

which of these screws does what?

cheers, rob :)

Re: carb advice
 

Neither of those screws will fix your problem. You need to get a new main jet. Screw A is the idle mixture screw and only affects the mixture at idle to about 1/8th throttle. I'm not sure, but that one looks like it's an air screw so turning it in makes it richer. Screw B is the idle speed screw. Turning that in makes the bike idle faster.

Re: carb advice
 

that carb has an air screw you need one with a fuel screw get a better carb
you also might check the needle to see where it is, raising it a notch could help when letting off the gas
also your air filter might need some oil on it,letting to much air by will cause it to run lean but it looks from the pic it is oiled properly look on the inside of it and make sure its got oil penetration all the way through
and you can screw in the air screw it might help as you said its shuting off the gas is where it is popping , depends on how much it is popping
could be a loose wire also but usually is a lean condition
cant really diagnose it with just popping some pop from being to rich,where you see the flame comming out of the pipe on the petronas bikes at the moto gp
you need to pull the plug out and look at it.spark plug tells all.
if its white its lean,a nice tan it what you are looking for,black is to rich
this is how you dial in your carb by doing plug readings
make an adjustment put in a fresh p[lug and go rip it while it wide open kill
it with the kill switch coast in read again,do this till you have the plug at the right color
heres a page to read on
[url]http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp?nav=31000&country=US[/url]
also heres another one
[url]http://www.strappe.com/plugs.html[/url]
that should keep ya busy for a few minutes