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Carbs issues low to mid rpm when engine warmed up

Posted: Mon Mar 04, 2024 3:05 am
by Vettehra
Hello everyone,

I'm having an issue, tried to solve it by my self, but second season without any luck...

So, I have Yamaha XJ600 1998 year model, by default it was 25kW, I found, that there was a limiter in carbs, plunges had higher plastic spacer to limit the power, to overcome that I bought new set of them. Originally they are for Yamaha vigaro xv250, but by the looks and dimensions they are the same, that's when my problems started...

When I'm driving on 1800-2000rpm and give some gas, it starts to shutter (only on hot engine), but if I give full gas it sputters a bit, and then goes like crazy, it's really hard to drive like that in city or just cruise.

I've cleaned carbs in ultrasonic bath, made full carb sync, measured valves, measured compression, played with pilot screw, checked ignition circuit, played with needles height, checked inlet rubbers. Long story short, tried everything from internet...

Could you guys helm me with that? What could be the issue? Maybe too stiff springs? Maybe someone already tried that and knows solution?