Reliable but minor glitches. Lots of questions

[scootnewb]

I decided to start working on the Tao Tao again to perfect it. My mods are listed in my signature.

The first problem is a slight stumble at take off or low RPM. I tried adjusting the accelerator pump but no joy.


If I am running WOT for a while and let off, it will sometimes back fire. Other times after going WOT and letting off it seems like the motor stops running and if I hit the gas there is a small delay before I hear the engine run.

The idle is erratic. I always thought this meant an air leak. I have a new manifold and spacer coming but the one on there now seems fine. Both inlets are capped as I use a manual petcock and removed the pair system. I sprayed carb cleaner around the manifold and it doesn't seem to affect the idle as if there was a leak there. 


I have a new 20mm  carb and I put in a 90 main and will adjust the float tomorrow according to this guide. 
I recently put the air box back on and have no idea on what pilot/main combo to use.
Right now, I know the pilot is too big and I'm hoping the unmarked one in this 20mm carb is smaller. I am going to order a 32 and 35.

www.49ccscoot.com/faq/carbtune.html#floatheight

Are there any other tricks to adjusting the float?

Is this a legit 20mm carb? I thought Glixal was legit. 

www.amazon.com/gp/product/B01EWHUHMM/



The float from the original gas sensor fell off into the gas tank. I am not sure if that could be contributing to the problem. I know it causes a problem if it is running low on gas. 

I also have new plugs on the way to do a plug chop. But otherwise it is very reliable. It starts first touch of the start and keeps up with city traffic. 

[ratdog]

Really, I think we should wait until you get the new carb on there, and go from there.

[GrumpyUnk]

That is, I think, the Keihin clone that Glixal sells on aliexpress, but without the letters on the vacuum chamber cover(black plastic part). It is a valid 20mm diameter if it is what I think it is.
I was able to use one to get some machines to start that had been stored, not running for a while. I did nothing with the pilot or main jet, and didn't even fiddle with the idle mix.
I would suggest just trying it as manufactured and shipped, right out of the box. No new pilot or main jets. See what it does. The jets fitted should be in accordance with the increased flow of a 20mm bore, right out of the box.
tom

[scootnewb]

ratdog ,

Yeah, you're right about waiting. I must have had low blood sugar when I posted because I swore off the scoot after deciding to get a Hellcat, or Venom. Last night I ordered a bunch of little parts for it. I am trying to cancel the orders now.

@grumpyunk ,

My scoot would not start with the 20mm on there. After reading the reviews another buyer had the same problem and said he had to raise the float height to get it to start then it ran fine. But I didn't catch that at first and that is why I changed the main to 90. I'm going to put the unlabeled jet that came with it back in and try to adjust the float height and see what happens.

[scootnewb]

I took a closer look at the float on the 20mm carb. When upside down, the seam in the float was not level. It was slightly pointed down. So i adjusted the metal tab and got it level, put back in the original main jet and installed it. No worky. It will not start. I removed it and there was plenty of gas in the float bowl. I put back on the Kei-hin and it started right up. I think I am just going to return it and work with the Kei-hin.

[GrumpyUnk]

Symptoms point to a defective carburetor. Not worth wasting more time trying to fix someone else' muck-ups. If the other carb works, use it.
tom

[scootnewb]

Thanks. I have taken your advice and returned the carb. I am back to the Kei-hin. I just can not get this thing running right. It always had a stumble at low RPM after installing BBK, cam, air filter and, exhaust, but wasn't too bad. I've since put back in the stock air box (so I could ride in the rain without stalling) and down jetted to 35/85.The stumble was still there and I took the main jet up from 85 to 90 cause with the 85 main when letting off WOT the engine would stop running like it wasn't getting any gas.. So i went up to 90 main. That seemed to solve the problem with the engine dying when letting off WOT but the stumble seemed worse. I tried a 95 main jet and it was too rich to rev up. At 35/92 the stumble is still there and it cuts out for a sec when accelerating to WOT. I tried a 38 pilot too and it didn't seem much different than a 35. I tried going down to 32/90 and it was too lean it would back fire. Is it possible valves adjusted too tight could cause a problem like this? I am at my wits end and have tried lots of jet combos.

[ratdog]

Two words... plug chop


Let’s SEE where you are at

[scootnewb]

Ok. For that you put in a new plug, then go WOT for a bit, cut the motor, take the plug out and see? I should have a picture by tomorrow at this time.

[scootnewb]

Dude, I bet it is the Glixal A-9 cam causing the drama.

I'm about to make a run to the store and get a new plug.

[ratdog]

I very much doubt it’s the A9 cam, unless it’s somehow damaged. If you read my post on information on the A9 cam, you will see that the A9 cam is little more then a stock cam that opens slightly later then stock. It is NOT the big high preformance cam that so many post it to be. The duration is less and the lift is the same. The only thing that could make it “the cam” is if it was not timed correctly. And if it were a tooth off. I believe the engine would be about not running. One tooth is like 11 degrees!

[katt]

Float position is the last thing i would adjust or suspect, not even sure its adjustable on Keihn CV, if you want to check float its simple you just run a little (starter works too) to fill carb up with gas while then open drain screw and measure how much gas come then take off the bowl (cover) and put the gas back in and see you should have as much as fits in the bowl simple and universal just invented it especially for you.

To adjust CV carb in the world properly follow my guide 49ccscoot.proboards.com/thread/23542/cv-carburetor-adjustment-progression-ports

Don't ask question in that thread, ask them here!