First off, jetting these carbs is easy as pie, so don't worry.
I just bought a couple jets at a time from SBP, they sell them singly or in little sets.
I can't give you a numbered jet size to use since that might cause you to melt your top end and come after the old moron that told you to do that.
There are many good jetting discussions with instructions archived that can be searched up on the forum.
I can tell you that you should go smaller than the stock, original jet.
Before beginning the jetting process take off the float bowl, remove the float, its tang (gotta call that doodad something?) and the pivot pin, the float needle will drop out so don't lose it or tear up the bowl's paper gasket.
Now you can grok how it all works.
The fuel inlet is stopped off by the float needle, lifted into closing by the tang when the float floats on the gas in the bowl and rises to the right level to just feed the main jet.
So as the engine sucks the gas out, at whatever rate, the float will lower, lowering the float needle from its seat, letting gas pour in until the level is reached to stop it off. You should check and set the float height before any jetting changes, since this will change your mixture, too.
The first time in, you want to check and set your float height, (specs on the forum somewhere) then change your jet by threading in the new one.
The float will stay adjusted unless the tang forks get bent and it doesn't take much to bend them, which is how you set the float height. So handle the carb gently whenever the bowl is off. The float needle and its seat, the place it closes off, must be clean. Any dirt might keep it from closing right and your engine floods.
The jet is removed with a screwdriver, but they are so tight I just use a pair of mini vise grips to loosen it. TIP: center up the float hinge pin before putting the bowl back on unless you want a nasty gas leak.
I didn't do this once. Gas running out, it made me feel so stupid.
The other aspect of jetting is the slide needle height.
As you open the throttle, the slide rises lifting a needle that obstructs a passageway fed by the main jet. The higher this needle rides on the slide, the richer the mixture at the corresponding throttle position. At full throttle the needle is no longer obstructing the passage and the main jet is flowing its maximum fuel. So the needle sets the mixture from idle to 3/4 throttle, the main jet at WFO.
Lowering the needle (by moving a circlip UP the needle (up a groove) will lean it out at low throttle openings, clearing up the blubbering and slobbering the new engines do quite a bit.
Raising the needle (by moving the clip DOWN the needle toward the point) will enrich the idle and midrange running.
The main jet is the full throttle/top speed mixture adjustment.
So you want to check the float height, drop the needle a notch if it blubbers, then test the main jet. When it is good at full throttle and making good power doink with the needle to get it to idle and pull well up through the midrange.
I like mine jetted so that I need to choke it for a cold start in the morning. Anyone that never uses the choke is running it a little fatter than I would.
If it gives trouble in the morning even with the choke, and you need a lot of tickling to get some gas into it, it probably has a low-set float.
Bend them forks. It's all just fun with gas toys.
This is just an over-view, look up those other discussions on here for particulars and photos.
Good luck with it.
yeehaawwww
I just fished a brake in a 80cc 2stroke .Iam running a 25:1 fuel mix rich i know but figured would be helpfull for breaking in new motor .I removed motor and placed rubber shims to dampen vibration. I still have at least a quarter tank left of 25:1 bike wont start .I removed plug and of course its black.I tighten the headbolts they didn't seem lose cleaned plug bike still dosnt run .Should i get new plug? Need advise.
