Need Help! One Cylinder not firing.

I put on new coil wires and cleaned the carbs and checked the fuel/float hieghts. I put it all back on and got it running. All cylinders are firing but the far right side. It is getting spark, and will fire if sprayed with carb. cleaner/starting fluid.

What could be the culprit? The carbs appeared to be clean.

took the carbs off and re-cleaned the pilot and main jets on the side not firing. We'll see tomorrow if that did it.

still not getting fuel to fire the number four cylinder. What could be wrong. I have had them apart twice and cleaned them. I see fuel shooting through the orifices.

You say you see fuel shooting through the orifices, is this just when the carbs are off the bike?

Is the fuel level correct in the float bowl? Have you done a clear-tube test to see what level they are set at?

badrhino wrote: I put on new coil wires and cleaned the carbs and checked the fuel/float hieghts. I put it all back on and got it running. All cylinders are firing but the far right side. It is getting spark, and will fire if sprayed with carb. cleaner/starting fluid....

Is #4 compression okay?

Is fat blue spark visible on plug tips with plugs removed from the cylinder head and viewed as the engine is being spun over?

If problem persists, even with good plug spark when viewed outside the combustion chamber, would install a brand new NGKB8ES spark plug (or whatever plug the FSM suggests).

It's remotely possible that #4 plug wire is shorting without interrupting the secondary loop.



Good Fortune!

kz750saskatoon wrote: You say you see fuel shooting through the orifices, is this just when the carbs are off the bike?
Is the fuel level correct in the float bowl? Have you done a clear-tube test to see what level they are set at?

If needed, here's some info about clear tube testing on Mikuni 29 smoothbores.

To determine fuel level inside smoothbore float bowls, without a side located drain screw, may collect fuel from hole at bottom of bowl.

Some folks adapt a spare 17mm bolt plug by drilling and fitting a nipple to attach the clear tube.

Click > Going First Class

May use a cone shape rubber plug pressed into the drain, with a hole through the rubber plug, and the clear tube fitted snugly inside the rubber plug hole. Then hold the rubber plug in position during the measurement.

Some minimal leakage won't affect the results, as fuel volume entering the bowl exceeds any leakage.

May cut an inch of 3/8 reinforced fuel line. The O.D. fits snug in the bowl drain threads and the clear 1/4 slides inside.



Good Fortune!

Yes, I have done the clear tube float bowl test and they all seemed to be in check. I took the carbs apart again and cleaned both the pilot jet and main jet in that carb and I am finally getting it to run on all cylinders.

Here is what I made to test the float levels and this way I could do all 4 at once. It only cost about $8 to make them.

Still might not be outa the woods yet. I gotta get the idle set and see if the carbs need synched.

Hey, that is slick! Nice!

Those fittings being plastic are just big enough that they screw into the threads with a little work, just gotta get them snug. Kind of big tubing and uses a bit of gas, but this whole process is messy. Definitely better than doing one carb at a time and trying to catch all of the gas from each individual carb. and losing it out of the one you have to do next.