air and feul screw adjustments

muffins · Post by **muffins** » Thu Jul 28, 2005 3:15 pm

I'm reading the instructions for adjusting the air and throttle screws, but I need some of the stuff dumbed down a bit.
In steps 2 and 4, I'm supposed to "reset the idle speed with the throttle stop screw." First of all, what am I doing? And second, what results am I supposed to see if I did it right?

If this helps, all I get right now is about 5 seconds of idle where it seems to get stronger, and then dies. But if I let it sit for a while, it will take full throttle for that same amount of time just fine, and then stop.

Thanks, muffins

vette76 · Post by **vette76** » Thu Jul 28, 2005 3:55 pm

adjust the air screw until you get the heighest idle. when you get the highest idle it may be idling too fast. then you would adjust the throttle screw to bring the idle down.

Post by **noiseguy** » Thu Jul 28, 2005 4:16 pm

You need to clean your carb, and probably check your bystarter to see if it's sealed properly. If it won't idle you can't really adjust the idle setting.

To adjust idle, put the scooter on the stand and/or on bricks to get the rear wheel off the ground. Adjust idle so that the rear wheel does not turn by itself (thus engaging the centripetal clutch.) Make sure after you play with the air screw that idle did not change, i.e. move up. Too high of an idle will burn up the rear clutch.

If you have a tach, set idle to 1800 RPM.

ferchja · Post by **ferchja** » Thu Jul 28, 2005 5:54 pm

Yours is doing what mine was doing. Your bystarter is not sealed.

Like noiseguy and others have said. If you set the screws to their initial setting per the manual it will idle fine if all things are working. Underline that ALL THINGS ARE WORKING. When it is idling fine then you can play with the screws to get it set to an ideal setting to maintain 1800 rpms with the correct air/fuel mixture. People think those screws are hit or miss, when in reality at the factory specified starting point it will idle, nothing more nothing less.

In all cases that you set those screws and it will not idle, then it is the bystarter, carb not clean, air filter (not in or too oily or too dirty), muffler clogged, throttle valve set in wrong etc. People think those screws will make or break the idle when the fact is those have the least to do with troubleshooting a non-idling scooter.

Like I posted awhile ago if you can start and get the engine to run at full throttle with starter fluid, then the idle circuit, screws and bystarter are out of the equation. If it runs then you can start to eliminate air filter and muffler and reed valves and main jet in carb and throttle valve. That leaves the bystarter, idle circuit and the screws. But I've posted how to bypass the bystarter to get it to idle, so then if that is not it, then you are left with the idle circuit and screws. If screws are set to the factory specs then that leaves the idle circuit. I should do a visio for noiseguy to post.

Let me know if you can post that noise.

Didn't mean to sound like I was flaming you or others, but trying to get others to see the big picture. In the end, they can search this forum and get their answer without having to waste time waiting for someone to tell them to do what they had posted 3 months earlier to a similar question. It seems people in general post without utilizing the forum to guide them prior to asking a question, ie. search. In reality, within a few months maybe a year this forum should have every answer in the book and would require no more new posts (at least the technical help forum) to be able to help anyone with a question or problem.

Rant over, good night all! Good luck