150 Lowboy idles but dies when throttle is opened. By paulio (Read 1,006 times)

[paulio]

Hullo! I'm new to scooters, but not to bikes. I'm getting out of motorcycles and into scoots so I bought this 2006 TNG Lowboy 150. It was not running (wouldn't you know), but I was able to diagnose a bad CDI using another thread on this forum. It currently will start and idle just fine. I am able to get it to go on the main jet by partly blocking the carb venturi with my thumb, and then it will run at full throttle on its own just fine.

This is what I have done so far-1) replaced CDI 2) Removed carb and cleaned all jets and all passages that I could find 3) drained old gas out of tank and put in fresh 4) checked for vacuum leaks by spraying carb cleaner while engine runs. 

Questions--could a weak spark plug cause this? Did I miss cleaning a passage? What's the little solenoid gizmo on the carb, and could this problem be related?

Thanks all!

[twowheeler]

Check the rubber diaphram under the cap. Look for tears or it might be pinched and not in its groove. It could also be jetted rich.

[Alleyoop]

Blocking part of the air intake cuts down on the air coming in. Do you have a AIR FILTER ON IT?
If not you need a AIR FILTER because no air filter to much air is being sucked in and not enough fuel.
So First put an Air Filter on it and it should run much better if still a little bit of problems we can adjust the carbs fuel mixture.
Alleyoop

[paulio]

Thanks twowheeler and alleyoop! Yes, there is an air filter on, and I checked the diaphragm on reassembly. I think I missed cleaning the mixture screw passage, so I'll try cleaning the carb again, and then check back in.

[Alleyoop]

If you have the AIR FILTER ON how in the hell can you do this?

I am able to get it to go on the main jet by partly blocking the carb venturi with my thumb, and then it will run at full throttle on its own just fine.

Alleyoop

[paulio]

Alleyoop It has the same symptom with air filter on or off. I got it to run on the main jet by pulling off the air box and fiddling around in the venturi. I found this out by accident while I was feeling to see if the slide would raise by itself. i must have a clogged passage for the transition between idle and main jet.

[Alleyoop]

Ok, get a video going on how it acts up with the air filter on it and you trying to give it some throttle and Video the carb area as well.
Alleyoop

[Bashan]

My thought is essentially what Alley said....you hit the throttle and you get more air and no fuel. Could you see the slide and needle pull up? There are little passages through the carb that transfer vacuum to the dome and pull the slide up. If they're clogged it's toast. I'd get a new carb...they're not that much.

[paulio]

She's running!!! I was not quite thorough enough with the carb cleaning, I guess.I pulled it back off, took EVERYTHING apart, cleaned every passage, and inspected all diaphragms. I think the slide bore is worn too much, so I will be buying a new carb most likely.

[jvino]

I wouldn't think you have much money in the scooter if it wasn't running so the new carb might get you out of the jam your in. Good luck keep us posted.

[paulio]

Just ran 50 mph up a steep hill. But, yeah, I think a new carb will make it better. Thank you guys!

[johnvino]

Wow 50 up a steep hill? Are you sure you spedo is wright? I do not believe that?