Stuck throttle!

[hammerforge]

So my carberator seems to be stuck at full throttle. Problem is that I am buggered if I know why. Took the assembly apart, and made sure that the pin was on the far side of the bushing and spring assembly.

Reassembled, and made sure that the adjuster on the top was as tight to the carberator as possible. theoretically, this should give the spring the most room to expand and limit gas imput, yes?

Yet, irregardless of where the twist throttle is (all the way forward or back), as soon as I engage the clutch the engine races to full RPM.

Any thoughts?

 

[stude13]

it indicates a lean condition, spray some wd 40 or carb clean at the attatchment points of the carb. i am taking into concideration your carb is assembled properly.

 

[Mountainman]

we could eliminate a few points of interest -- fast -- by

disconnecting cable at carb -- start engine -- should normal idle

if not -- carb problem

if so -- cable or twist throttle problem

I hate that full blast of raw power when I ride that thing

 

[MotorMac]

carb

Take the carb right off at the intake, take off the air filter , holding the carb in your hand look into the air intake of the carb and twist the throttle the brass slider should be moving full open and close if not then thats the problem and cable needs to be adjusted or the brass slider is sticking. hope this helps, not sure if you did this already.
P.S. sometimes the brass slider is turned the wrong way around and will not close completly becuase its sitting on top of the idle screw,if you had the slider out you will see a little bevel on th bottom of the slider, thats how the adjusting screw adjusts engine speed. Mac

 

[QuadManiac]

There is a slot in the slide that engages a tiny pin down in the bore. IF the slide is rotationally misaligned, it sits on top of that pin (throttle open) instead of sliding over it (throttle closed).

 

[hammerforge]

Thanks guys!

In fact misalignment was the issue. ON my way up to college wednesday, of all things, the throttle cap on top of the carboretor came unscrewwed.

When I put it bakc in, I had the notch lined up with the pin, and the slot lined up with the screw Needless to say, this limited my range of throttle options.

At any rate, problem is now solved and I can now focus on adjusting the idle screw to my liking.

 

[Lorcher]

I was having a similar problem. Turns out my intake manifold gasket was blown--causing a very lean condition for me. Once I replaced the gasket,I was off and running again. I have found that when something goes wrong, it's best to look at the entire area of the motor with the problem. I was goofing around with my float and cables and everything only to accidentally notice the gasket was gone. Look at the whole system when trouble shooting. Most of the problems I have had have been blown gaskets.

 

[BirthNight]

This just happened to me tonight. I don't understand how it "happened" though. One minute everything was fine. Put the bike in my Dad's truck - drove across town - unloaded, and fired it up and BAM!!!!! full speed and no throttle control. Pretty scary when you don't know what is happening. I think we got it figured out although - now I think I will always be a little scared that at any moment it could happen again.....

 

[John-Forrest]

I was having exactly the same problem as above. The info you guys gave above was very helpful for troubleshooting what it was. I replaced a 49cc engine with a 70cc engine and had to rebuild whole system from scratch. The first time I got engine going, it just took off and there was that loud screaming noise when I pulled in clutch. I kept thinking throttle was stuck. It turns out I had brass slider on BACKWARDS! The slot part should face AWAY from idler. I assumed since it went all the way in, it was on right, but that was causing the whole thing. Anyway, I finally have this thing up and running normally.

 

[Middle Path]

This helped me out. I too had the slot on the wrong side after unscrewing the throttle and putting it back in. Thanks!