Engine running FAST or quitting---no in between

[mustanger]

Dear Dreamers:

My 305 came out of winter hibernation with an annoying problem. When it starts, it runs like a rocket. I can bring down the rpms with the throttle or opening the choke, but it's like walking a tight rope in either case. The engine just won't run at a normal speed. Bringing down the rpms causes it to stop. You can sometimes prevent this stopping by turning the throttle up again or closing the choke, but then it's back to running like a rocket. Sooner or later you'll turn it down too much and lose it. So if you're following this, it will only run with lots of gas and at high rpm.

The carburetor you say? Well I've got two bikes and I swapped carbs and the problem stayed with the original bike. The other bike ran fine on the problem bike's carb. I checked the timing and point gap too and they seem alright. Now I'm out of ideas.


Can any of you help?

[Jim Stuart]

Sounds like its leaning out. Check low speed jets for blockage. Also for sticking slides.

Jim

[mustanger]

Thanks for you reply


It sounds like you don't believe it's not the carburetor. I'm having trouble believing it too, but like I said, the bike runs the same way with either of two carburetors and another bike runs fine on either carb. That makes it hard to blame the carburetion

Is there anything else it could be? and BTW I didn't understand what you said about sticking slides.

[LOUD MOUSE]

Is the slide going to the bottom of the carb?. ...............lm

Thanks for you reply


It sounds like you don't believe it's not the carburetor. I'm having trouble believing it too, but like I said, the bike runs the same way with either of two carburetors and another bike runs fine on either carb. That makes it hard to blame the carburetion

Is there anything else it could be? and BTW I didn't understand what you said about sticking slides.

[305]

could be a vacuum leak

[mustanger]

That's a good point!!!!!!!! Now, where's the best place to look for a vacuum leak on a little motorcycle engine?

[LOUD MOUSE]

Did you look down the throat of the carb and make sure the cable or something else is holding the slide off bottom?. .............lm

That's a good point!!!!!!!! Now, where's the best place to look for a vacuum leak on a little motorcycle engine?