Lolorides Posted October 25, 2023 Share Posted October 25, 2023 Hi Everyone Hoping someone can suggest ideas to help solve a problem that's driving me mad. THE PROBLEM: The bike starts and idles (initially needs choke). After a few minutes, she's warming to the touch and is happy to idle without choke but her revs drop away if throttle is applied, sometimes to the point where she actually dies. By feathering and twitching the throttle I can raise her revs past this baulking point but she repeats the baulk on throttling until I've done this a few times, sometimes with a bit of a backfire. It can take a good 5-10 minutes of idling and fiddling before she's rideable and it's not clear whether it's simply the warming up that makes the difference. WHAT I'VE TRIED: I've followed the Haynes manual to set the idle screw and air/fuel mixture screw then tweaked them (1mm at a time) to find an even idle, then tweaked some more to find a spot where she doesn't baulk (right term?) at the merest bit of throttle. It seems to require hair-breadth adjustment which doesn't seem right. I'VE ALSO: Cleaned the carb and replaced the needle valve with brand new Yamaha part, checked and adjusted the valve clearances, checked her fuel line, cleaned her air filter, checked and cleaned her spark plug, replaced her battery with a stronger model. The issue is that I adjust her idle and air/fuel screws, get everything feeling good, take her out and she rides fine, but she's right back to square one next time I start her. It's like something has reset itself. I've been through this process over and over and over again. I clearly shouldn't have to touch the screws once they've been set. NB - This bike had been fiddled with in various unwise ways, so I;m not 100% sure if her carburettor is the original spec but it looks about right, and it doesn't seem to have visible model number so I can't check. If anyone can suggest anything at all that might help, I'd be immensely grateful. If any clarification needed , please ask. Lolo Quote Link to comment Share on other sites More sharing options...
Moderator drewpy Posted October 27, 2023 Moderator Share Posted October 27, 2023 checked float level? Quote Link to comment Share on other sites More sharing options...
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