Engine Overrevving! Tryed changing carb and throttle cable. STILL DIDNT WORK!Help.

[StrontiumEthics]

My engine was working just fine last week. Then I havent rode it in one week. I made sure the petcock was closed, and choke was close before I leave my bike out for long period of time. Now today im riding it and it takes longer to start (Pullstart), and when I give it full throttle, and release it it just keep reving. When I release the throttle I keeps reving REALLY high, then a couple seconds later the RPM's go down. I thought it might be carb so I adjusted the idle screw. Still didnt change anything. Then I replaced the carb, and still didnt change anything. I am at wits end! What do I do now? It just keeps overreving, but it does idle but after a while it RPM's increase. What DO it do!

 

[motorpsycho]

it sounds like the slide inside the carb is sticking when you give it throttle.
Remove the slide and make sure you have it in right. Line the slot in the side of the slide up with the pin in the carb. body.
when the slide is inserted into the carb correctly, it will slide down to the botom of the carb. nice & easy with very little resistance.
if the slide is slightly off, it will bind on the pin and cause the throttle to stick or not work at all.
since you changed the carb,. and it is doing trhe same thing, i would double check the slide.
sometimes a drastic change in temperature can also cause the slide to stick in the carb. due to expansion and/or contraction.

 

[StrontiumEthics]

LoL. Im sure that the Slide does stick I can feel it comming back down every time, and also Feel the pull on the throttle. When I insert it is does indeed have little resistance.

 

[Al.Fisherman]

LoL. Im sure that the Slide does stick I can feel it comming back down every time, and also Feel the pull on the throttle. When I insert it is does indeed have little resistance.

If the piston is sticking, I've had that problem...I took it out and took some sand paper 80-120 and sanded it while rotating the piston, finished up with some 280...nare a problem since.

 

[StrontiumEthics]

When I insert it is does indeed have little resistance.

I made a little type = ). I meant to say that it doesnt have any resistance when I put the barrel in the carby! It goes down quiet smooth. But I will double check again tommorow. I do have another barrel to cross check. However, I did use another throttlecable and it still didnt work the way it should work.

 

[Al.Fisherman]

I made a little type = ). I meant to say that it doesnt have any resistance when I put the barrel in the carby! It goes down quiet smooth. But I will double check again tommorow. I do have another barrel to cross check. However, I did use another throttlecable and it still didnt work the way it should work.

In that case take the throttle handle apart and check to see if the cable is binding in the sleeve, check for kinks in the housing. Check that the throttle handle is free, and easy. When you took it apart did you put the spring back in?

 

[StrontiumEthics]

Yep I put the spring back in. But I think im gonna double check the whole throttle assembly. I know that IT HAS TO BE A FUEL Feeding problem. Either a serious Airleak, or maybe just the throttle. Have anything else in mind?

 

[AussieSteve]

StrontiumEthics, without the engine running, if you open the throttle then snap it shut, you should hear the slide hit bottom.
Also, with the carb off, fit the slide without spring etc, tighten the carb top cap fully and try turning the carb alternately upside-down and right-side up. The slide should move freely.
I had one carb that jammed on full throttle only when the top cap was tight. It must have distorted the carb body slightly. (I think that Ron, (Al.Fisherman), had the same problem.)
I had another carb with a tight slide and had to buy another (third) slide before I got good throttle operation. Finally, mine works well and doesn't stick at all.

Ron, mine are coated slides, so sanding isn't really an option. The coated slides sometimes have small dings, though, and need touching up lightly with very fine wet&dry paper before they'll move freely.

StrontiumEthics, I meant to add - you would have been better off posting this in the appropriate '2-Stroke Engines' or '4-Stroke Engines' section.
I'm assuming that you have a 2-Stroke HT engine, although everyone's advice above could apply to either.

 

[StrontiumEthics]

very interesting I will be checking it out soon. Possibly could happen.

 

[210061741]

The most common cause i found when my engines ever did this were as stated the sticking cabel.

But a air leak will do the same thing.
And it could be anywhere.

Head gasket. you will see a little oil where the gasket is leaking on the bottom of the head. Pretty common.

The base gasket allthough not common.

And the seal underneath the magneto magnet could be blown.

Most likly you would have some oil or nastyness under the mag cover.

Check 4 an air leak.

The carb leaks where it attaches to the intake sometimes too.

If it revs high when you pull the clutch in and settels down after a few it's an air leak.
If it revs and revs and revs the cable or slide is sticking.