Update:
So I checked the spark plugs; they were all black except for number 2, which was clean enough. The number 2 ignition coil seems to have been chewed on by something, but it seems to be only cosmetic. Spark plugs numbers 2 and 4 gave decent spark (blue and straight), number 1 barely gave any spark, and the spark on number 3 was jumping all over the place. My question is: could this be the reason why the bike doesn't start, or is there likely to be a bigger problem?

As always, thankful for any sort of input!


Original post:
Hi, Im Kristoffer from Sweden. Recently picked up a quite rough cbr600f3 (1998) from facebook marketplace and have been trying to get it running, the previous owner had it as a stunt project but had only gotten as far as taking the bike apart installing a keyless ignition and a steel cage. The DAI system seems to be missing the split hose in the front, I only have the big hose going into the carbs.

I started by replacing the battery and cleaned the carbs, the third float bowl was full of old dried fuel so I figured that was why it didnt run, reassembled and put the mixture screws 2.5 turns out. Now when I hold the ignition and let the starter crank the engine doesnt idle, all I get is pops from the exhaust, (Im bad at explaining, see attached videos). Ive checked hose diagrams in a service manual but I have a hard time interpreting which type I have, there seems to be 3: 49-states+Canada, California and Europe(?). I have not checked actual fuel pressure or spark. I know fuel gets to the floats since I opened the drain screw and fuel came out.

Videos: IMG_1809.mov, IMG_8169.mov, IMG_8168.mov

Its my first time trying to diagnose something mechanical at this level, I have only done small things like changing fuel lines on a pitbike and spark plugs on a boat: What Im trying to say is ive probably missed something obvious. Is there a standard protocol to follow for situations like mine?

 

Did you clean out and inspect the jets?

 

Hey there.
I would say your carbs need to be throughly gone through. I would bet good money on it.
In the video it should you giving it more throttle to try to get it to start. That isn’t necessary on a proper bike.

While you are trying to start it, spray some ether or starter fluid i to the carbs and see if it tries to run then.

 

Thanks for the answer, yes, 3 float bowls looked great but i sprayed through the jets with brake cleaner and compressed air anyway. One of the bowls looked like an abandoned fish tank, full of green stuff, and no light shone through. Those jets received a thorough clean. I also swapped the float needle between two of the carbs since the dirty one didnt seem as springy as the rest, that way I could see if the needle itself is the problem if it comes to take off the carbs again.

Long text but the important part is, float bowls are clean and light now shines through all jets! Im currently trying to elliminate spark as the culprit, havent gotten the time yet though...

 

Thanks for the reply! Float bowls have been cleaned and jets sprayed through.

So you are saying I shouldnt need to give it any throttle?

Before I cleaned the carbs, I tried with starter spray and got some coughing, not as much as in the videos here but some and also a backfire from the exhaust. Back then it didnt even cough with fuel but a little with spray so I figured the carbs were the problem. Now Im trying to find time to check the spark plugs.

 

That is correct, when the bike is cold give it a little choke but no throttle. After it starts the choke isn’t needed.
Tjat is of the bike is running properly.