Have a problem that has been posted on the CBR 600 Forum but no one seems to have an answer. So here's the problem. My step son has a '99 CBR 600 F4, he laid it down onceand took the time and care to put it all back together again, it looks better than it did before the accident. Now comes the problem, the bike fires right up runs great when it idles and when it opens up the throttle in neutral. When you take the bike out on the road it will run great for a few miles and then it will just shut down completely. If he lets it sit for a about 5 mins or so, it will fire right back up and run for a few miles and then shut down again. He did take it out and when it shut down, sprayed some starter fluid into the front air dams and it fired up again. The fuel pump is working, he had that tested a shop. No one seems to have an answer for this problem and since it fires up when he puts starter fluid into the front air dams, it doesn't seem to be an electrical problem. Anyone have any ideas on why this would be happening? I've seen a few posts on the 600 F4 forums, but no one seems to have an answer. Any ideas out there?

Any help would be greatly appreciated!!!

 

fuel tank vent is clogged.

 

Well, we checked that out too. Actually put some air pressure through the tube on the bottom of the tank, and then listened in the tank (with the gas cap open) to hear the air passing into the tank, and air is coming through. Actually ran the bike and when it shut off, opened up the gas cap to see if that helped, and it didn't help out at all.

Thanks for the input!!

 

does it sputter then die or does it just shut off, BOOM just like that? can you crank it when it dies?

 

Have you drained or cleaned the carburetors? My old 600's carbs proved to have small hardened gasoline deposits that only rested on the bottom of the bowl until throttle open time, then all four of them would get sucked up and clog the intake, completely shutting down the bike. If the carbs are clean, and if a 99 F4 has a vacuum diaphragm in the petcock, this may help.

 

with the described symptoms you are running out of fuel. For some reason or another your running the carbs dry and they are only slowly filling back up after the bike shuts down. check the float settings.

 

To answer some questions, it just dies "boom" like its run out of gas (it doesn't sputter), or like the electrical system shuts down. It still cranks over after it shuts down, the starter spins but doesn't sound like its going to fire up. He had the carbs re-jetted since he put on a full exhaust system, so I can only assume that the mechanic did check the floats on the carbs, but I can't be sure of that. I will have to check to determine if it has vacuum diaphragm in the petcock, I'm not sure if it does or not. He's going to get a new fuel pump just to see if that's the problem, one person stated that it might be pumping enough gas to idle and run for a bit, but when you run it for a long time at 5K RPM's it might not be pumping enough gas.

Thanks for all your input its greatly appreciated!!

 

well, that certainly sounds plausible... i wouldn't throw parts at it until you know it's bad though...

 

I'm gonna go ahead and sayhe either didn't check the float height or he put the floats in wrong and made the height adjusment with the floats in upside down....a little far fetched but still totally within the realm of possibility.

And please stop sprayingstarting fluid into the bike. It's bad.

 

Nonsense. Mechanics NEVER mess up![:@]