Adjusting Idle Speed

[>ScCruisin<]

Im newto engine in general, which screw on the carb is the one the adjust idle? My bike is new and probably has a bout 40 miles on it, and recently ive noticed that the idle is much higher than it was before, to the point where it almost stalls the engine when i release the clutch because i cant pedal fast enough to ease it in. And I read some of the other threads and its not my cable because i tried twisting the throttle back after accelerating and it doesnt help.


Thanks for the help guys.

 

[Bikeguy Joe]

There are three possible things going on here....your idle screw has moved (it's the only screw on the carb, left side) the cable adjuster on top has unscrewed, or you are running lean due to the common air leak. Does it run hotter now? (air leak) Start harder? (air leak)

 

[Bikeguy Joe]

Oh yeah, can you kill the engine with the choke? (If not, or it take a long time to kill it, air leak)

 

[>ScCruisin<]

Ok so after a long ride yesterday, about 20 miles, all of a sudden the idle was back down to where it should be, maybe a little low, because it was right to the point where any lower it would stall. So i assumed that after this long ride, the idle screw had maybe vibrated back to where it should be. Then when I was riding to work, the idle shot up again, way higher than ti should be. It almost sounded like the engine was revved up as high as it could go. Then at top speeds, it would bog down and max out @ around 20 mph, when usually it goes around 28. When I arrived at work, i looked to see if anything was wrong, and the carburetor was completely loose, to the point where air must have been coming where the gasket is. I tightened it back up but something still seems off. Is this what my idle problem was? What can I do to fix it? Thanks...

 

[Bikeguy Joe]

What still seems off?
That would definitely give you a lean condition and the symptoms you described.

 

[>ScCruisin<]

The idle speed is still a bit off and it doesnt seem to have the pick up that it did before when i went hard on the throttle...

 

[matt167]

air leak.. probably the carb connection

 

[Norman]

the gasket that comes with these engines are not the best if your carb came loose once withthat gasket it might be time to make a replacement gasket buy a good gasket material at the auto parts store. you can make gasket dies out of water pipe find a pipe with the right ID and grind the pipe to a sharp edge to cut the holes you will need for the gasket, to cut the holes if you don't have a gasket punch/cutting set.
Maybe I should do a poor boy gasket cutter post for you guys let me know?!
Norman

 

[2door]

Sccruisin,
I have to assume when you said the carb was loose and you tightened it, you were talking about the intake manifold where it attaches to the cylinder. As Norm said, replace that gasket and use a good grade of high temp silicone gasket sealer. Also. while you're doing that check the carb where it slides onto the manifold. You do not want air leaks at that point either so smear some of that silicone on the manifold before slipping the carb on. Don't overdo it. You don't want silicone in the carb or manifold, just on the surface where it seals. Also don't overtighten the clamp on the carb or you'll break the tabs off then you will have an air leak. Get back to us if these suggestions don't help.
Tom

 

[fat80ccdb]

3 1/2 turns runs sweet oh yea keep carb level........ iam 350 lbs and i go about 20 mph after 200miles

 

[ShakenBake]

I also have the same issue. I have a brand new gasket on the intake manifold. I have a very good and tight connection complete with lube where the carb connects to the intake manifold. I would like to get some feedback on the TWO adjustement screws on the carb. Yes there are two screws there not one. I have a SKYHAWK Gruber 66cc engine. The One screw you were probably referring to is the idle screw and is accessible from the factory. Turning it counter clockwise slows the idle down. I had a problem with my engine racing at stops and clutched in prior to launching. I ride with a small flathead in my pocket and have to adjust this some when I ride. HOWEVER , can anyone tell me what the other screw is. If you didn't know it was there I bet you'll see just a brass cap covering it. Well you know what that cap doesn't do anything but keep you from getting to the to other adjustment screw. You can remove this little "plug". I took mine off by drilling a hole in it with a small drill bit and then a larger one and larger one incrementally making it larger until I had drill the whole cap off. It is a shallow brass plug and it is located to the left of the idles screw when you are facing your engine on the right side of your bicycle. Once you get this cap off there is a screw inside identical in appearance to the idle screw. by default mine was set all the way closed tight clockwise when I got to it. I have been experimenting with adjusting it but I honestly don't know what it's purpose is. My question is since it is there for a reason and can be adjusted, can someone tell me what this screw does and how it effects my motor. Now assuming someone can answer that question how do you set it in combination with the idle screw. I'm looking for a good response to tell me how to dial these screws in to get the best running performance out of my little engine. What is the method for setting these properly, what do I listen for, what do these screws actually do etc.. Please help! I forgot to mention that my throttle needle DOES NOT have the notches on it to set the gas mixture. Mine only has one setting on it. I would like to keep the discussion on the carb setting screws if possible but I will consider replacing the throttle needle as well.