What the he$$ is going on with my throttle?

[dz]

I just did an engine swap on my atc90. When I fire it up, the rpm's go instantly up, not redline but high. I made sure that the throttle is not stuck. When I hit the gas, the rpm's will go up more. If I want to run it at all I have to keep the choke on but it chokes it down. The way it is now, its not rideable. Could the gasket from the carb. tube to the cyliner head be bad? What could be wrong? Any help would be greatly appreciated.

[nitekrawler]

Here is a few things to try.
1. take the "box" apart to the throttle (where the handle bars are) and lube it in there.
2. Clean the carb
3. Check to make sure correct jets are in the carb.
4. Inspect carb. Make sure float is ok. & make sure the needle isn't bent and is seating ok.
5. Check idle screw for proper adjustment
Tighten snug, then unscrew 1-1/2 turns out

[dz]

Before I did the swap, the other engine ran fine. I will try those.

[nitekrawler]

Before I did the swap, the other engine ran fine. I will try those.

Post back with your findings

[smokinp]

Try taking the slide on the throttle apart and make sure the spring isnt tangled up.

[Domingo]

Make sure your throttle cable isnt stretched to tight. My Suzuki did the same thing when I redid mine. Here I wraped the cable around the wrong things, and it was pulling to tight. Just check and make sure.

[dz]

Good suggestions, thank you all. Soon as I get some daylight I am going to go implement some of these suggestions.

[Wickedfinger]

I once put the slide in backwards on my '82 R ........ Boy that was fun. Almost blew the engine apart that day. 30* out, ice cold motor, went from 0 to 8000 rpms in 1 second. Anyway, just a thought.

[dz]

Its weird though I did not touch the carb. at all, only the carb. tube that goes onto the engine.

[J.D.]

Possibly an air leak too.....

[atckowalski]

Your throttle cable may be kinked or damaged in some way.

[TimSr]

Not to sound like a jerk, but did you back the idle screw off? I realize you didnt mess with the carb, but when you attach a completely different motor to it its not unusual to have to alter settings.

[KASEY]

While you were working on it and the carb was hanging by the cable did it get pulled out of the adjuster on the top of the carb and now it is not seated back in good?????
when you work the throttle can you hear the slide bottoming out on the idle screw???