No top end unless its going up hill.

[Denis Zen]

I recently changed carbs on my 80cc anbull bike motor and cant seem to get the motor to run smoothly at full throttle UNLESS i am going up a slight incline then it runs smoothly until the load is gone then back to rrrrraaaaattttttt.

The bike idles fine and runs smoothly until I get to the last 4th of the throttle and it just blahhhh. I live 58 feet above sea levels

Ive taped up where the carb and manifold connect so Its not an air leak. Ive played with the sparkplug gap, no help. My bikes getting plenty of gas. (Checked fuel filter and gas line.) I use Husqvarna oil mixed at 30- 40% and fires right up first kick.

Should I try swapping the jet from the old carb or what? This is driving me crazy!

 

[Nightster]

Sounds like it could be a jet issue, maybe some others will know more. But since you’ve checked everything else I would focus on the jet at this point

 

[Denis Zen]

Thank you brother, I found an old carb with the same thread jet that I can solder closed and redrill. What size should I make the hole I wonder. Time to google it. Thanks for responding!

 

[Oldbiscuit]

What size jet was in the carb you replaced ? Measure it and start there.

 

[Oldbiscuit]

What size jet was in the carb you replaced ? Measure it and start there.

Bigger question is why did you replace the carb in the first place ?

 

[Denis Zen]

It was the standard size in the anbull stock carb. Size unkown as it wasn't marked and the standard size in the "h.p." carb. I dont know enough about them to be more specific.

 

[Denis Zen]

I replaced the carb because it was supposed to be good to go with out any
adjustments and an auto choke.

I havent replaced or changed any jets so far. I am still messing with the spark gap. I have 5 sparkplugs and I am systematically going from 23 to 28 and so on. So far it doesnt seem to make any difference at top end.

This is what leads me to believe its a jet problem. I even changed magnetos in case it wasnt producing enough spark. And same thing.

 

[Denis Zen]

Oh I am running a niome flex tailpipe also, could that have something to do with it? I could swap to the stock one but I dont like my tailpipe riding 8 inches off the ground .

I am going to try the tailpipe swap just for sh*ts and giggles.