Ok,
I'm getting so frustrated with this bike. I really could use some help here. To give you the history of the bike. It's a 98 CBR600F3. It has around 16k miles on it. The bike used to belong to a friend of mine. It was working fine, then one day the fuel pump went out. He never got around to replacing the pump due to him being in the navy and out to sea alot. So by the time I bought the bike, it had sat for about 6 months. I picked up a fuel pump off a F4 from our local junkyard. I replaced the fuel pump and the bike would try to start, but wouldn't. So I figured from sitting for so long then trying to be started, the plugs were fouled. They were. I bought new plugs and put them in. The bike finally started. It was running, but it was't running too healthy. The next day we went to start the bike and it was dead again. I pulled out the plugs and they were kind of fouled, but not too bad. I cleaned them off and reinstalled them. Tried to start it again and still nothign. Pulled the plugs and cleaned them again. Still nothing. When I try and start the bike, it will just turn over and turn over, but not start. When I quit trying to start it, I get a big backfire. Fuel pump is working, the fuel tank is full and the battery has a full charge. Any ideas?

 

have you replaced the gas?if not i would recomend it. Also, i know it might be a pain but your carbs might be gunked up. if you dont wanna clean them do this. Empty your tank, get a gallon of can-2(sp?,racing gas) and pour it in there. if its not to bad gunked that will clean everything up and also clean your top end. being it is running poorly i would try the racing gas thing first after you drain your tank. i did that to a old dirtbike and it works great. hope that helps

 

Didn't you already clean the carbs? Sounds like you're getting too much gas with all the fouling and backfiring. Is the F4 pump putting out too much gas? No starting with backfires can also be a timing issue. Coulda jumped timing but I'm more convinced that you got carb problems.

 

sounds like u aint gettin no spark

ignition module or anything in there??

 

Backfire = spark. But if the spark hits too late then you can get backfire -- too early and you diesel like a ****. It's easy enough to see if you're gettin fire. Just take a plug out and reconnect it then turn over while holding plug close to the frame (no where noticeable) and you'll see fire jumpin off the plug to the frame. Timing is easy to check also. Valve cover and timing cover off and check your marks against the service manual.

Too much or not enough gas is the hardest thing to check without butt loads of expensive equipment. And I'm taking a big leap of faith that you have already cleaned the carbs and put good gas in it (believe you said that in another thread).

Good luck.

 

The tank is full of new gas. However the carbs haven't been cleaned or sync'd in who knows how long. After thinking about it and talking to a few people, it seems thats what I need to do first. From sitting if there was gas in the bowls, it probably gummed up and is causing problems. I'm just dreading doing it. I have heard from a few people that the carbs on the F3 are a pain in the *** to do.

 

Yeah it's not like the good old days. I rebuilt the carbs on my '75 CB 550 because it was having the same problems after I assembled the whole bike (it was in boxes). I would spray the **** out of it with ignition fluid and it would just turn over and then fart. Havent really looked at the carbs on an F3, and I imagine it's a pain. The 550 was easy.

 

Not sure how the newer carbs work on these bikes, but what was happening to my CB was that 2 of the bowls were flooding, and 2 of the others were dry. The two that were flooding was because the floats were stuck, rusted over form sitting so long. The other two had a fuel clog right inside the port. Took a paper clip and cleaner. This allowed the bike to fionally run, and somewhat smoothly. Until i bought a rebuild kit and did it for real.

 

paper clip might be to big, when i cleaned mine out on the ol'dirtbike i used a piece of wire brissel off a brush and stuck it throught the needles and then held it to the light to make sure it was clear. neonspeed do you have a service manual for that bike? if not email me and ill hook you up with a person that will proubly have it in adobe acrobat form (mine was a hugh file,100megs, but it was worth it.) that should also help you with the war of the carbs.

 

It sounds as if you should take the carbs off the bike ( not that hard) and take it to a shop that has the proper equipment/tools for this job. There are drill bits made specifically for this application. If you can not find someone willing to or unable to do it, ship them to me and my mechanic does this all the time in the shop. We do rejetting/ carb rebuilds, synchronizing ( need to be on the bike for that)
Good Luck, but it is MORE than likely the carbs just need cleaned...have you taking a compression reading off each cyclinder yet?? Just curious