Ok guys, I could use some input cause this issue is driving me insane. It all started while at freeways speeds the bike had no power, even with the throttle pinned wide open it was stuck around 80mph. Around town it pulled strong and behaved normally. So figuring it was a fuel issue I cleaned the carbs, replaced the fuel filter, cleaned the k&n and put everything back together. Now the bike fires right up, runs fine for about 10 - 30 seconds and dies like its out of fuel. At that point it wont start until sitting for awhile, then fires right back up and dies again in the same manner. When I pulled the plugs after it was running they are damp with fuel not oil. I originally suspected the fuel pump, but, it feels like it is pumping. Though I'm beginning to think that is not the issue. Any ideas?

1999 CBR600F4

 

Ok I'll throw this one out there...............

Could the vent to the fuel tank be blocked? If the vent is blocked fuel won't flow properly to the carbs. If it happens again, open the fuel cap and see how it runs then. If it runs well, fuel vent is blocked.

Hope you solve the problem.

Cheers, SB

 

I've tried starting it with the gascap off to the same effect, and checked all the hoses.

 

OK, what model and year bike is this ? How many miles on it ? Service history ?

 

I was having a similar problem for a while, still do if I forget about it lol. I have a 99 f4 too and it was slowly dieing whenever I rode at high speeds for over 20 minutes, it wasnt a fun problem, worked perfectly on the streets though. But after dieing it would start up, run rich for a 30ish seconds then die again. repeat.

Turned out it was the fuel line folding over whenever the tank was lifted and put down without the fuel line being pushed into an out of the way spot. Not sure if thats your problem, sounds like it could be and its simple enough to check. Drove me crazy for months!