Just picked up a 600RR today with only 6500km, hasn’t been run much for a few years. Was going great on my way home, then after about 45 minutes at 120kmph the bike would not accelerate. If throttle was very very light the bike would maintain speed but would seem to bog if more throttle was applied. Pulled over, turned the bike off to talk to a friend. Turned it back on and it ran great, accelerated great. After a minute or two the same problem came back. Rode the bike around for a while, problem always came back a minute or two after the bike was started. Not dependent on coolant temp. The fact that it runs great for a minute or two after starting makes me think electrical. Ideas?

 

Thinking more fuel issue than electrical, has it been stood long before you bought it, check your breather pipe to the tank first and then pump ,if the breather pipe is clear

 

Thanks for the reply and suggestion, I’ll make sure to check that breather hose.

I ended up tearing into the bike tonight. Got the tank off and took the pump out. Tank is full of what seems like rust. Sloshed some fuel around in the tank and poured it into a clear container, there is a lot of garbage in there. Took the outer “fuel filter” off the pump and cleaned it out. I’d rather fix this tank than buy a new one, will probably try vinegar to dissolve the rust.
Would make sense that this is the problem, it ran good while the filter was filling up with garbage, and then off and on since then when sufficient fuel couldn’t be delivered.

 

That could be your problem, I know in the US there are a lot of Preparatory Fuel tank Fluids but just look at You Tube and decide the best for you, You might even just get away with a good flush now you have cleaned the tank out