How old is the engine. Is it the classic Vacu-Jet diaphram carb, (carb on top of the gas tank). Or is it a recent float type carb, (tank on top of the engine).
Old style: First adjust your idle speed till the engine stays running. Warm up engine. Now start adjusting the mixture jet. It only has one mixture screw. Start at 1-1/4 turns out from seated. Turn out till it runs crappy, then turn in at 1/8th turn increments. Wait a few seconds between adjustments to let the engine settle down. You may have to readjust the idle as you find it's sweet spot. Keep going in till it starts to stumble again. Now go back out till it smooths out, (usually only 1/8 turn).
Now nail the throttle a couple of times. If it stumbles badly or stalls, back the screw out a little at a time till you can hit the throttle with no stumble.
Be aware the these carbs are a compromise at best. Adjusted as above, for good idle and throttle response, is a little rich for full throttle, max RPM, power.
New style: Same as above, or you may only be able to adjust idle speed. If you have a mixture screw it's only for the Idle circuit. Adjust it as above. If it runs crappy at open throttle, it's most likely dirt in the main, (fixed) jet. If it's clean and still runs crappy, all you can do is try adjusting the float, not alot you can do here.
Good Luck
Old style: First adjust your idle speed till the engine stays running. Warm up engine. Now start adjusting the mixture jet. It only has one mixture screw. Start at 1-1/4 turns out from seated. Turn out till it runs crappy, then turn in at 1/8th turn increments. Wait a few seconds between adjustments to let the engine settle down. You may have to readjust the idle as you find it's sweet spot. Keep going in till it starts to stumble again. Now go back out till it smooths out, (usually only 1/8 turn).
Now nail the throttle a couple of times. If it stumbles badly or stalls, back the screw out a little at a time till you can hit the throttle with no stumble.
Be aware the these carbs are a compromise at best. Adjusted as above, for good idle and throttle response, is a little rich for full throttle, max RPM, power.
New style: Same as above, or you may only be able to adjust idle speed. If you have a mixture screw it's only for the Idle circuit. Adjust it as above. If it runs crappy at open throttle, it's most likely dirt in the main, (fixed) jet. If it's clean and still runs crappy, all you can do is try adjusting the float, not alot you can do here.
Good Luck
thanks 4 the info it looks newer the tank is on the mini bike no tanks on motor the carb like hangs off the intake with 2 screws and the breather kinda sits next 2 the carb its weard it idles but boggs if i leave the chock on 1/2 way no bogg it has a ajusting screw on 1 side of carb and an ajustment under the bowl
Adjustable float carb?
That's and oldie, (but goodie!). Predates the classic Vacu-Jet mentiond before. Much more flexible than the two carbs I previously discussed.
The side adjustment is your Idle mixture, (seems ok, so leave it alone for now). The bottom is the main (high speed) jet. If it bogs when opening the throttle, (but does ok with 1/2 choke), it's too lean. Turn the main jet out a 1/4 turn at a time until it runs good. Then play around with it, (1/8 turns in or out) till you get it to run good when hot.
If this engine's been sitting for a while, you'll most likely have to readjust as the carb gets cleaned out after a few tanks og gas.
That's and oldie, (but goodie!). Predates the classic Vacu-Jet mentiond before. Much more flexible than the two carbs I previously discussed.
The side adjustment is your Idle mixture, (seems ok, so leave it alone for now). The bottom is the main (high speed) jet. If it bogs when opening the throttle, (but does ok with 1/2 choke), it's too lean. Turn the main jet out a 1/4 turn at a time until it runs good. Then play around with it, (1/8 turns in or out) till you get it to run good when hot.
If this engine's been sitting for a while, you'll most likely have to readjust as the carb gets cleaned out after a few tanks og gas.
Last edited:
The carb you have is known as an "up-draft" carb. To properly set these carbs is different from setting the types listed above. These ones are adjusted while the engine is running, at idle and at high-speed. The jet on the side behind the air-cleaner is the idle, to set this start the engine and turn the jet clockwise until it sounds like it is going to stall out (remember the position of the screw slot) then turn it counter-clockwise until it does the same (remember the position of the screw slot and how many turns you made from the other stalling position). You want to be in the middle of those two spots.
Now to adjust the high-speed jet. The engine has to be at high-speed to do this so put the mini on a milkcrate or something sturdy as not to let it fall off. The setting for this jet is the same as the idle jet. Rev it up and keep it there, turn the jet in until it wants to stall and out until it wants to stall then your spot is in the center.
good luck
Now to adjust the high-speed jet. The engine has to be at high-speed to do this so put the mini on a milkcrate or something sturdy as not to let it fall off. The setting for this jet is the same as the idle jet. Rev it up and keep it there, turn the jet in until it wants to stall and out until it wants to stall then your spot is in the center.
good luck
If you use this technique, (bike stationary, wheel off the ground). Make sure you can put some load against the engine. A governed engine will run @ rated 3600rpm quite easily with no load. The gov will nearly close the throttle to maintain rpm. This, in turn will introduce the idle curcuit making tuning difficult. So, have someone apply pressure to the brake as you rev the engine.
Good Luck
PS. All the carbs listed are tuned with the engine running.
Good Luck
PS. All the carbs listed are tuned with the engine running.
Last edited:
I ask the help
Hello. My name is Vick. I wish to become Striptease. I constantly train. I have removed video and I wish you to ask to look it and to tell to me about my errors, or to prompt, as I can improve the technics.
movie free
Hello. My name is Vick. I wish to become Striptease. I constantly train. I have removed video and I wish you to ask to look it and to tell to me about my errors, or to prompt, as I can improve the technics.
movie free