OK here is the situation. The bike is a 1993 CBR 600. While warming the bike up one day at half choke it just died out. It was restarted but ran very rough. After some investigation I found that the 1 and 2 cylinders were firing but the 3 and 4 were not. I know the coils control the 1 and 4 and the 2 and 3. There is gas in the float for the 3 and 4 but I am unsure if it getting to the cylinders. It appears to have a very light spark on the 3 and 4 spark plugs but it is very hard to tell. Does the 3 and 4 carbs connect in any way regarding fuel delivery? Can anyone diagnose this problem or suggest a specific solution if you have had the same problem. Thanks for the help.

 

Anyone with an idea?

 

Just maybe an opinion or a general idea of the problem will be a big help.

 

how do you know its not running on those 2? spark plugs?? check the engine wiring. could be somthing there. seems like if it was a carb issue it wouldnt just happen all of a sudden and on only 2 of them.

 

change the sparkplugs

 

Could your floats maybe be stuck?

 

Ok its back to basics . First I presume its still not firing correctly???? Get the tank off and rig a fuel tank to it ( Lawn mower tank is Fine ) its what I have used. Start the thing up and gently pull the plug caps off with insulated pliers Free them off first, see which cylinders are weak . If any cylinders are not doing anything ,then listen for the spark cracking as you move the lead away from the plug. If you cant here anything ,stick a spare plug in the cap and restart the engine watch fotr the spark If you have a spark then put the leads back on and fire up again and watch to see if carb dash pots rise up ( Diaphragm are known to split ) if they all go up , Drizzle a little fuel from a syringe into the cylinders doing the least and see what happens . if the engine races up I am affraid its carbs off and see what not happening . Off the top of my head If the bike is left on the side stand then debris will collect in the lowest carb Bike should be stored vertically .In the UK my bike actualy got carb icing whilst being left to warm up at a fast tickover . but given a few seconds the ice clears If Its an older bike then stick a multimeter in the plug leads and measure the resistance -- anything over 10K and they are on there way to being Buggered . I think they measure about 5 or6 when they are new . My mate's Yamaha R1 blew its carb off the rubber manifold when it started once That was a funny fault and a bit unexpected . Oh by the way CBR fire one coil but two cylinders together ( Lost Spark) technique . Hope this helps I dont think I have missed anything