Hi guys, I'm new to the forum (first post) and this issue is entirely why I'm here! I've lurked and cannot find an answer, and I've also scoured Google. So, to the issue in question. I bought a 96 Smokin' Joe's CBR600F3, maybe 4 months ago. I bought it non-running but mostly complete. I'm not a noob when it comes to mechanical things, I just work primarily on cars. Now, the issue I'm having, in the simplest of terms is: the bike will not run properly. I'll describe the issue, then what I've done to fix it.

The bike will fire cold with a new set of plugs, idle screw all the way up, and sound decent. It doesn't like the choke, the choke lowers the RPMs. It will flare to 3-4k and then settle to 1500 in about 15 seconds. At this point, it doesn't sound great, but it's firing on all cylinders. Then, about a minute or so in, the idle speed will slow, and the bike looses cylinders until it shuts off. The bike will not start and run properly after this. It sounds like it's running on 1-2 cylinders.

Now, the work I've done.
The spark plugs have been replaced at least 5 times (it fouls them out).
The carbs have been hand cleaned, then chemically, then ultrasonically. They were rebuilt and set to factory specs in the process. All the rubber components are good, including the diaphragms. When the chem dip didn't cure my issue, I had them ultrasonically cleaned professionally. This also did not cure the issue. (The carbs were factory takeoffs, the sync was checked).
I replaced the regultor rectifier with a new mosfet unit from an R1. The wires were nasty from someone messing with it prior. I cut the wires back and soldered on fresh ends. I made sure the harness was connected to the correct connectors on the new r/r.
I visually checked for spark, then ohmed the coils and made sure they were within spec. I checked the coil wires.
I installed a new battery.
I started playing with the idle air adjustment, no change improvements, so I set it back to factory specs.
-I attempted to run it without the air filter
-I ran it gravity fed, then with a new fuel pump, I also jumped the pump to see if that helped.


So that's the deal so far, and where I'm at currently is trying to make sense of what could be the problem. Any help is appreciated. The only modification is a slip on. Thank you for your time.

 

Hi and welcome to the forum. Do you know any history regarding why it was not running or why it was apart? It's firing on all cylinders, what makes you say that? All header pipes getting hot at the same time? Checked float height ? Do you have good compression?

What part of the world are you in?

 

I'm down in South Florida. I don't have any idea what the original cause was. And I can tell audibly, as you can hear it drop cylinders. I honestly haven't had it running long enough to check think about checking the headers. Every time I try to start it, it sounds okay, I let it idle a bit, then it drops cylinders and dies. After that, it won't run again. It will fire on a couple cylinders while cranking, then start backfiring out of the exhaust. The plugs all look consistently carbon fouled. Compression isn't something I've checked yet.

 

Sounds like your carbs are way out of tune. If you’re starting the bike with no choke, than they are dumping too much fuel. I’m also gathering this being how the problem gets worse as the bike warms up. This would also be why you’re fouling plugs so frequently.
Take the carbs off and break them down into they’re own individual carb and give them a good cleaning. You can get a carb bath from Auto zone. Don’t let them sit in there too long or it’ll remove the zinc finish on things like screw and the throttle levers. Rinse and blow them out thoroughly. Clean the jets really well and make sure you can see light coming out of them. You don’t have to worry about the brass bits being damaged from the cleaner. For parts, I HIGHLY recommend new o-rings and the carb insulators (parts between the head and carbs). This will make sure there are now air leaks and you can tune the carbs. Once everything is assembled, the carbs will need to be tuned. If you don’t have access to one, there are vacuum gauges that can be used or the Motion Pro carb sync tool.

 

marc0011, I've cleaned tons of carbs before. These carbs were taken off, given a soft clean. Then taken off again, broken down, and chem dipped. After that didn't work, I ordered a kit to replace the o-rings, and purchased an ultrasonic cleaner from Harbor Freight. I then broke them down individually again and cleaned them. This also didn't cure it, so I had a friend of mine stick them in his industrial grade ultrasonic cleaner (it's about the size of a dishwasher). After this was all done, I had no change from the first time I cleaned them. I have a sync tool, four individual vacuum gauges, and I checked all of them. The air mixture screws were set at 1.5 turns, then 2.25, 2.5, 3.5 and everything in between. The vacuum gauges were hooked up the entire time while messing with the idle air adjustment. The bike also won't rev out past 5k or so with a load on it. It will rev freely in neutral, but when you're riding it, it won't. (The one time it ran long enough to take it down the street and back).

 

I'm curious what jets are in it and also what air filter you're using. Does it still have the D.A.I. system installed and is the Air Vent operational?

 

I wouldn’t go with jets yet. If it were jets, then this issue would be while in higher RPMs. Sounds like have to get back to the basics. What is the compression of your cylinders? Do you have good spark? Will the bike run if you spray in starter fluid down the carbs?