High RPM low speed

[Tanner Logan]

Backed out to where the throttle isnt touching it. Throttle cable is not even attached when I am trying this. Air mixture screw is at 2 1/4 turns as suggested. I also tried it fully closed, 3 and 3 1/2 with no change. Fresh cleaned carb, new oil, new gas.

 

[crassius]

did you take off the air filter & look at the slide? is it sliding all the way down?

 

[Tanner Logan]

Forgive me still new to this. What exactly do you mean by "slide" ?

 

[MotorBicycleRacing]

Update :

So I took apart the carb and cleaned everything thoroughly. Not a single bit of dirt or blockage in ANY way.

I have learned that I in fact had the choke on as opposed to off. Yes yes I know believe me I am making fun of myself RIGHT now.

You had the carb off so look at how it works.

Choke on is when the plate blocks the carb throat.

Choke off is when the plate is sideways and not blocking the
carb throat.

 

[MotorBicycleRacing]

did you take off the air filter & look at the slide? is it sliding all the way down?

It's a 50 cc 4 stroke and uses a butterfly carb.

There is no slide.

 

[MotorBicycleRacing]

Update :

So I took apart the carb and cleaned everything thoroughly. Not a single bit of dirt or blockage in ANY way. I have learned that I in fact had the choke on as opposed to off. Yes yes I know believe me I am making fun of myself RIGHT now.

However this brings on a new question. Why is it that when I attempt to turn the choke off the engine revs like crazy and begins to take off. I cannot even turn it 25% without the RPM's shooting through the roof and the bike taking off. I have tried the air mixture screw in all positions but cannot understand why this is happening. It's as if I was running full throttle and I even have the throttle cable out at the moment. ANY further help would be greatly appreciated.

So there was nothing wrong with your carb except you were trying to
run it with the choke on?

When you put the carb back on you must have made an air leak so the
air mixture screw doesn't have any effect.

Putting the choke on when you have a large air leak will compensate
for the leak.

Did you mess the carb intake gasket up or put it in the wrong place?

 

[MotorBicycleRacing]

Forgive me still new to this. What exactly do you mean by "slide" ?

If you have a question about 4 strokes put it in the 4 Stroke Forum
or you will get answers from people who think you have a 2 stroke
bicycle engine.

 

[Tanner Logan]

I assure you I looked at it thoroughly and just did not understand what he meant by slide.

And yes it seems the only thing is the choke was on. But what would make the engine rev as I am attempting turning it off? Not just rev a slight bit but enough to where I am uncomfortable turning it all the way due to the high RPM. Something as simple as an air leak could cause such a problem?

When I reattach the carb should I tighten it down obnoxiously tight or just a good fair amount? Oh so many questions that only trial and error/success could fix..

 

[MotorBicycleRacing]

I assure you I looked at it thoroughly and just did not understand what he meant by slide.

And yes it seems the only thing is the choke was on.

But what would make the engine rev as I am attempting turning it off? Not just rev a slight bit but enough to where I am uncomfortable turning it all the way due to the high RPM. Something as simple as an air leak could cause such a problem?

Yes, large air leaks in the manifold will make the engine scream to redline
like they are going to blow up.

Find the air leak.

 

[Tanner Logan]

Thanks for the patience and help. Hopefully you wont hear from me anymore unless it's about the finished product.