bought my first bike last year, 99 honda cbr 600 f4. ran great for about two months and then while warming up it just died. could not get started again. new battery (that i have killed trying to get this bike running), cleaned carbs 4 times, new intake boots, new plugs. finally got running but now its only firing on cylinders 1&2, 3&4 are cold. swapped coils no change, swapped plugs no change. swapped #2 and #3 ignition coil connection and still no change. so good coil sticks, plugs and getting spark to all 4 cylinders. pulling my hair out trying to figure this out cause i cant get it to the mechanic. just wanna ride.... thanks for any advice. oh i cant see a spark wit the plugs out but know its gettting spark due to them running inside the bike.

 

What do you mean you can't see the spark with the plugs out? You want too make sure you are grounding the threads of the plug on the chassis...

 

Possibly a CDI issue...................
Are all 4 plugs getting fuel ?

 

we had a guy in the 954 section go through the same issue - hell, his shop couldn't even figure it out.


all it was, was the coils were hooked up wrong. best of luck, but be sure to check the wiring diagram

 

Per the manual the cylinders are hooked up corectly. I can open the screw on the bowls and fuel comes out not a lot but its there. And didnt know to ground the threads thought u just touched the prong to the motor will try that and post back.

 

not a lot but its there

Are your needles and seats working in the float bowls ? When you open the drain screws fuel should come out at a high rate.....

Is there maybe a blockage in the fuel tank filter ?

thought u just touched the prong to the motor

Plug won't fire properly if you do that,

 

shadow, when i open the drain it drips out then as i open more it doesnt rush out just runs out just past driping if u know what i mean. not a high rate but a small stream. doesnt look right even to me and i dont have a clue what im doin. lol. it is the same on all four drains about the same stream. gotta charge my battery to do a spark test but i did find the top vac hose that goes to #3&4 was spit so cut it closer and fixed. when it starts and runs on two cylinders prior to this i can hit the throttle and if it doesnt die the #3&4 rubber diaphrams flutter. kinda hard to explain but it sounds like there trying to open but not evough pressure to keep them open so they thump or flutter. thinking thats bc there not firing and cant sustain pressure to keep them open. any thoughts.

 

ok update, pulled plugs out 124 fired yellow blue spark right away. 3 sparked after about 6 tries and right after spark backfired like a 12 guage. garage with doors shut couldnt hear for a bit....lol so after i put spark plugs back in i found a vac hoes that goes to 3 &4 on top of the carbs to be split so cut short and fixed that. charged battery (its a bad battery only 12.54v) jumped to my truck and it ran like **** but 2,3&4 header pipes were hot but 1 was getting hot. after about 1 min it cuts out and dies. heres what im thinkin.... not enough juice from battery to fire all plugs and keep running. not getting a steady supply of gas to keep running after all in float bowl is gone. am i on the right track? but my concern is what only two cylinders then after backfire and vac fix only one clyinder barely fires and others are good. very new to bikes so any input would be greatly app. thanks all.

 

Double check the r/r. If it's failing, you won't get proper current at the coils to fire reliably.

Ern