stalls at takeoff and hard starting and up and down idle

[MidwestFlashRT]

It starts good when cold but after that when i start it after that i have to throttle it a little and when it idles it idles high then goes really low, and at takeoff it stalls really bad
What i have done:
Valves adjusted
new carb
cleaned new carb
new coil
Any ideas whats wrong???

[goosestale]

Have you done this adjustment?

By Fox

The Idle Mixture Screw affects the IDLE ONLY! It has no effect on the high speed mixture whatsoever contrary to internet rumors.

To set your idle speed:

1) Turn mixture screw on the side of the carburetor all the way in and then back it out 2 1/2 turns.

2) Warm up the scooter for at least 5 minutes, longer if you are in arctic weather.

3) With the scooter warmed and idling slowly (900-1200 rpm) on the center stand, turn the idle mixture screw SLOWLY to the right until the idle gets rough and slows even more.

4) At that point stop and turn screw back to the left SLOWLY until the idle smooths out and reaches it's maximum speed.

5) After you find the sweet spot, re-adjust the idle speed screw if needed to a speed that is fast enough so the lights aren't too dim but below a speed where the back wheel turns while on the center stand. If the wheel is turning then you will fry the clutch at stop lights.

6) It may require some fiddling until you get it just right. You'll see.

The mixture is affected by seasonal temperature changes so it should be done 2 or 3 times a year as the weather changes, and after every valve adjustment.

Keeping the air filter clean on a regular basis will ensure proper idle mixture as well as high speed mixture.

Mixture screw:



Idle speed screw:

[petersgc16]

As horrible is this is to say, I'm happy to hear that you're having this problem. I have been plagued with this exact same unexplainable issue for a year now. I've also replaced the carb, adjusted the valves, and tried every suggestion anyone has for me. The weirdest part is that i replace the carb and the scooter will run perfect for 6 days and then it will begin to stumble and idle poorly again. I'm convinced that my scooter is a lemon and there is an internal issue, because there are so many of these scooters and the majority of them do not have this problem. My newest solution has been to order an 85cc kit with a new cylinder head, high performance cam, bigger bore carb, high flow fuel valve, high performance cdi and coil. I'm hoping that by replacing everything it will solve this unexplainable nightmare. The parts should arrive next week, after I install everything I will let you know what happens and if continues to run well for more than 6 days!!

[scooter 49]

Try a different electric choke.

[MidwestFlashRT]

As horrible is this is to say, I'm happy to hear that you're having this problem. I have been plagued with this exact same unexplainable issue for a year now. I've also replaced the carb, adjusted the valves, and tried every suggestion anyone has for me. The weirdest part is that i replace the carb and the scooter will run perfect for 6 days and then it will begin to stumble and idle poorly again. I'm convinced that my scooter is a lemon and there is an internal issue, because there are so many of these scooters and the majority of them do not have this problem. My newest solution has been to order an 85cc kit with a new cylinder head, high performance cam, bigger bore carb, high flow fuel valve, high performance cdi and coil. I'm hoping that by replacing everything it will solve this unexplainable nightmare. The parts should arrive next week, after I install everything I will let you know what happens and if continues to run well for more than 6 days!!

Well, before u dump a bunch of money into it, get this: every time i take the carb apart the pilot jet is clogged, and after getting it unclogged it runs perfect, for like 2 minutes til it gets clogged again! I just put another hi performance fuel filter and air filter is clean too, i dont get why it keeps getting clogged like this, but it is the source of it running like this!

[goosestale]

 Have you installed another filter between the fuel pump and the carb? I don't know why you keep getting cloggs like that, but I would clean the gas tank out, and get my gas somewhere else. Also do you run premium or regular? You should have premium in there.

[Fox]

I agree. Drain the tank and flush it out.

[frostyman]

Sounds like it's time to get back to the basics.

Depending on what kind of fuel filter you have, IF you have one, some have glue that breaks down and goes right into the carb----especially the junk OEM ones.

Get rid of the junk fuel/vacuum lines and get new clamps if you haven't or if needed---before/after flushing the fuel system out, but before it's reassembled. Look for pinches/kinks in the fuel/vacuum lines if they are strapped to the frame with a zip-tie or such. Just looking at the lines sometimes isn't enough.

I do recall reading about a certain model of a TANK scooter, having to have all the vacuum fuel pumps replaced with electrical pumps---not too sure why, but I read it.

Is your gas tank higher or lower than the carb? I think that maybe had something to do with it....

[goosestale]

I do recall reading about a certain model of a TANK scooter, having to have all the vacuum fuel pumps replaced with electrical pumps---not too sure why, but I read it.

The Baron Retro150, my scooter, has the electric fuel pump. The tank in my '05 is under the floor boards. I can't remember if it was '04 or '06, but Baron had the fuel tank under the seat for one year, so the fuel flow was down to the carb. If the tank was more than half full it caused flooding. They changed it back to under the floor the next year. I don't know if that relates to why it has the electric pump. My '09 iScooter Classic, has the fuel tank under the floor with a vaccum pump. Either electric, or vaccum, hasn't been a problem as far as fuel flow. The pumps are set slightly higher than the carb.

[MidwestFlashRT]

All new fuel line, brand new (as in 2 days ago) hi performance Briggs and Stratton fuel filter, new carb and that, tank is above carb and i replaced petcock already, has a strainer on that too so i dont see how all this gunk is getting past 2 filters!!!

[petersgc16]

I have also cleaned/flushed out my tank, replaced all of the fuel and vacuum lines, installed a high performance fuel filter. I originally had a tank mounted fuel valve and converted to a non tank mounted valve because a scooter shop said that the tank mounted valves sometimes had problems. Dumb question, but which jet is the pilot jet ... main jet, low speed jet, or choke jet ?? The problem you are having with it being clogged all the time could be the same reason mine runs perfect for 6 days before stumbling and bogging again.

[MidwestFlashRT]

I ride this one when the chinese one breaks down lol

[MidwestFlashRT]

another thing i dont get is its the more expensive Walbro carb, the second one, first was the original,
my freind has a Tank Urban sporty and it has original everything with 1400miles and has never ever given him trouble, with the cheaper carb it has never clogged!!!

[petersgc16]

Well at least you have a good spare scooter. I have two of the exact same chinese scooters and they both bog and stumble. Also, I have tried the walbro carb and that cheaper one, and they both stumble and bog after about a week, i'm cursed.

[frostyman]

Have you guys tried using something like Seafoam?