KymcoForum.com

Thanks for the suggestions. I put in a new plug ... one of the first things I did. I set up the idle mixture and speed screw. These actions made it idle fairly well, but I still noticed surging. Started it a week later, and it was back to idling at 4K again. I have ordered a new bistarter. These things only cost 20 bucks. Actually, I could get a whole new carb for about 60 bucks. If the scoot continues to exhibit this wierdness, I may just replace the carb and get one with a manual choke (Huzzah!). I will try the Seafoam, as per your suggestion. Funny thing is, the scooter runs better now than it did brand new ... when traveling at regular traffic speeds, up to about 60 mph. I would think that, if there were some blockage in the carb, the scoot would not run so well down the road. The issue is only the idle. If it goes any higher than 4K, it is going to engage the centrifugal clutch and start burning that, if it is not already making some contact. I am going to replace that bistarter ... or to be truthful, I will bribe a friend to help me with that. I am very limited when it comes to wrenching skills.

Checked the resistance across the bistarter ... measures less than the 10 ohm spec, but I am using a cheap meter. I would think that, if it measures about 7 ohms, the switch might still be closing OK. Very hard to tell. I should probably replace the stupid thing. I got over four years on the original, so I have probably seen my money's worth out of it. Why, oh why did they have to put those in instead of simple, manual chokes!

You mentioned that you changed vacuum hoses. I took one look through the inspection door under the seat, and Oh Crap! Looks like spaghetti down there. It has hoses all over the engine .. some with T connections ... some look like vacuum hoses but appear to lead into wiring harnesses. There is one up top on the vacuum chamber that loops over and terminates in the air (nothing-goes nowhere). There is a smaller, short hose that does a quick loop to the ACV (air cutoff valve). I know some of these have to be fuel delivery hoses and some are probably pollution control junk. Long story short: I have no idea which of these hoses is/are actually vacuum hoses that might need replacing. Which did you replace?

Hmmmmm I have the reverse problem with my Kymco BW 150. It is idling about 4K. I reset the mixture to factory specs and set the speed screw on the linkage so that it would idle at around 2K ... a little fast, but OK. I noticed it was surging. Started it a week later. It started almost instantly and went directly to 4K, where the idle stayed, even when the engine got warm. I am suspecting maybe a vacuum problem or something else afoul with that steeenking bistarter (hate those ... much prefer a manual choke). Anybody have a similar problem and hopefully a solution?