hey guys, im brand new here, literally just signed up! I have a 99 cbr900 that ive been struggling with for quite some time. im hoping the collaborated knowledge here can result in a non motorcycle shop fix. ive owned the bike for a few years now and never had trouble with it till recently. I was driving along and suddenly it acted like it was running out of gas, pulled over and noticed some crap in the tank, added more gas and still ran crap, and had stinky smoke out the tail pipe. ended up parking it for a while after not being able to start it even with starting fluid. so i pulled it out last week and got it to run, but not full power. ive got a lazer thermometer that ive used to determine which cylinder is firing. It changes randomly, sometimes culinder 1 and 2 will read 600 degrees and 3 and 4 only 2 or 300, then it changes. I figured it was crap in the tank and carbs so i put fresh fuel, in line filter, and cleaned the carbs. now what im getting is no heat on cylinder 1, at full temp the exhaust is only 190 ish and the rest 400-700. i can choke out the #1 cylinder with no change and shoot it with starter fluid with no change, if i do the same with the other 3 i get results, either increased or decreased rpm. i did a compression check and theyre equal at around 150psi. i checked the coil for spark and i have spark, i have all new plugs and still no fire on #1 i pulled the valve cover and can see the lifters moving properly. the only thing i can find that doesnt seem right is when i test the spark, if i hold the plug with channel locks against the frame it wont spark, but if i pull it away a tad and leave a gap between the plug and the frame it sparks there and at the tip of the spark plug. it really seems like its spark related, its got even compression and all the carbs mist a lil bit of fuel evenly, including cylinder 1, and ive tried starter fluid and it does nothing on cylinder 1. im not sure what to do next, ive taken the carbs off and will go through them again, but they seem to be flowing fuel. if i choke out the carbs with a wrag, it gets wet with fuel, on all of them. is there any way to check the voltage of the coil? im thinking it may not be enough spark to ignite it. is it common to replace the coils? any help would be greatly appreciated.

 

i had my 95 run rough for a while . fill up with gas, started it it back fired and died . restarted ran rough. turns out the back fire through the carbs blew off the rubber vacuum hose on the carb boot and was suckin air making it run lean. try spraying some started fluid around the carbs and see if the rpms increase. if so you have a vacuum leak.

 

You say you have cleaned the carbs, but did you get them ultrasonically cleaned? Sometimes you get them jammed up so much that that's the only way to sort them out.

Dave