Brand new owner of a 99 CBR F4 with 45km (not miles) that has been sitting for the last 3 years. Gas had all but evaporated.

Changed the oil, spark plugs, and cleaned out the carbs (excluding pilot screw). I was very careful with the carbs and did only one bowl at a time, the float pin & seat were in excellent shape.

Now when I try and start it, the engine completely floods, gas in spark plug wells, gas in cylinder head, won't fire at all.

I dried the gas out and tried starting it without the vaccum hoses that connect the carbs and the valve cover and I did get a few puffs of smoke out the back but still no start.

I believe the petcock is not a vacuum style petcock on the F4. Should it flow constantly in the reserve and on position?

Any help would be greatly appreciated.

 

Ok so the bike will run with the gas tank disconnected but dies out out once the gas runs out. Can someone please confirm if the petcock should flow a steady stream when ON?

If the gas tank is connected, it runs for a bit then sputters and fuel starts flowing out of the carbs. Do all air intake connections have to be connected when starting to prevent flooding?

Really starting to think it may be the float bowls as the carb has been cleaned out 3 times now and the float needle and seat are spotless.


Any other possible problem areas that would cause it to flood?

 

The float height should be 13.7mm +or- 0.5mm. To check remove float chamber, hold carburettor so that the float hangs down, then tilt it back until the needle valve is just seated, but not so far that the needle's spring-loaded tip is compressed. Measure the distance between the gasket face (remove gasket first) and the bottom of the float with a ruler and check that the measurement is as above. You used to be able to bend the float tang to obtain the correct measurement, but it is recommended to replace the float and needle valve as the float height is not adjustable on these carbs. Hope this is the problem. I had a similar problem on my 1980 BMW R100RS that dumped fuel all over my boots and bending the float tangs on the carbs cured the problem. Sounds like your problem too.

 

Sorry for the ultra bump, but this is my exact problem. What solved this for this guy?

 

Back from the dead lol just got an e-mail notification about your problem.


For me the problem was the routing of one or two of the air hoses. I double checked the haynes and voila! Bike ran perfectly. Good luck!