Hi guys,



I am helping a friend get his bike back on the road after it has sat for about 4 years. It's a 2000 Honda CBR 600 F4. The deal is if I can get his bike going I can use it for my road test. Hence my eagerness to see it running again!



The bike was parked with no storage prep more than 4 years ago. We emptied the gas, new battery and with a bit of gas poured into the carbs it started right away. Everything seemed good until he took it for a ride.
When in neutral the bike idles fine and revs well over 10k. On the road it is fine in 1st and 2nd (will red line if required). Shift up to 3rd and the revs drop and stay at ~5000 rpm for a little and then either;
The revs keep dropping until it stalls out or a sudden but intermittent burst of speed and revs up to 10-11 thousand
3rd seems to be hit and miss, shifting up to 4th usually causes it to stall out. Can't get it any higher than 4th.


Downshifting From 4th or 3rd or 3rd to 2nd A throttle blip on the downshift usually results in a very delayed response


So far we have tried - New gas, new plugs, check the breather hose, removed the carbs and cleaned the jets and fuel bowls, (we could not get the pilot screw out as it has that stupid D head on it) ran it without the air filter, checked the fuel filter in the tank and the petcock valve and changed the fuel filter.


Could it be the pilot screw? I'm not sure what that does but thats the only part of the carbs that we didn't clean.



I don't think it will come into play but it needs an oil change and there is a coolant leak. These are next on the list but from what I can read online there would be no link to above problem because of these issues?
Any idea what the problem could be?

 

That's exactly what mine was doing, I know you said you changed the plugs but do it again it might help, you might have fouled them out playing with the carbs.

 

I would inspect your carbs again. I missed cleaning an idle jet. After I put it back together and sync'd them, bike runs like new! I would advise you flush both the brake lines as you need to stop also

 

Thanks guys.

When we pulled the old plugs out they were in great shape. Not fouled, no sings of overheating or any of the bad stuff the manual warns you of.

We were very careful when doing the carbs and when we had them out ran compressed air through them as well. Thinking it might be the pilot jet as thats the only part we didn't take out?

 

So it was the fuel filter in the end! Running nicely now.