Delbert posted a topic in Moped, Scooter, & Mini/PocketHello folks. Brand new to this forum so please bare with me.....I picked up this little bike (1974 Panther SS 2 stroke single cylinder, Yamaha clone) partly disassembled and managed to get it running but...as I open the throttle it will rev up to about 1500- 2000 rpm then abruptly stall and it usually takes quite a bit to get it started again. I've had the carb apart at least 6 times to clean and look for a plugged circuit and nothing !!! I've checked for leaks between the carb and cylinder and installed new O ring....hooked up a timing light to check if spark was disappearing as the revs went up but spark was continuous and strong. If I try enriching mixture with the "choke" it stalls too. The carb is a very simple Mikuni slide/needle type. From what I find it looks like float should set at 25 mm which is where it is now but I've tried higher and lower with the same symptom every time. I've oiled the air filter to try to enrich the mixture but nothing changed. The bike rides around running real nice as long as I don't throttle past about 1500-2000 rpm (no tack) The bike is in near perfect condition with only 134 actual miles and I suspect it's low mileage may be due to its perhaps having this problem from the very beginning of it's life...though I have no knowledge of it's history. It seems like the high speed circuit in the carb isn't pulled into action. Also....If I slowly bring the revs up to a sweet spot right where it begins die and hold steady it will steadily oscillate, revs slightly dropping and then recovering, over and over until you let off on the throttle where it will drop to a nice steady healthy idle. Also....with the slide adjustment screw all the way in it idles quickly at about 800- 900 rpm....seems slow to me, like it's not getting enough fuel. Sorry for all the words but it is what it is....Any suggestions would be very much appreciated. UPDATE::::FOUND THE PROBLEM !!!!!!!! It's a RICH problem not a lean like I had thought. I found the problem accidentally when I spun the top off the carb for the last time and flipped the top upside down and the needle fell out !!!! Whoever had put the new throttle cable in didn't put the needle in properly, they had just wiggled it through the slide spring dropping it in through the top....I couldn't work because this would leave the needle WAY too high causing the VERY RICH condition when revs came up to where high speed circuit was activated. I hope this can be helpful to someone. Very satisfying to FINALLY solve this one. Now it starts with one kick and runs like a brand new bike !!!
My son has been trying to get his 1962 (yes that's right 1962 personally imported) Honda 90 to run but to no avail. He has replaced points, plug, condenser, coil. He has checked all the wires for breaks. The bike ran last year but quit after tooling around a few times, maybe a total run time of a couple of hours. He was running it without a battery, could that cause component failure? Maybe be rectifier failure? Some forums say these older models ran fine without a battery but I'm beginning to wonder if this thinking is correct.