2001 Yamaha V4 115 dead cylinder

[captnbigfish]

Have a cylinder that appears to be dead. Has good fire, switched coils, switched out cdi, new fuel pump, rebuilt carbs, checked reeds,
has good compression. After rebuilding carbs runs much better, idles fine now but when I pull the plug wire off that cylinder(#4) no change in engine performance. Is this common or should I notice an engine change like I do on the other cylinders? If so what else could be the problem?

[99yam40]

why play with spark producing parts if it has good spark?(fire as you called it)

Good compression, good spark(at correct time), you are left with needing correct fuel to air ratio.

maybe it is not idling as well as you think, if one cylinder is not changing it's running when unplugged.

did you follow the link and sync procedures in service manual after putting carbs back on?

[captnbigfish]

I did not, I looked in the manual for the procedure and will give it a shot and let you know how it works out.

[TownsendsFJR1300]

Plus 1 on Yams post.

You have two, two barrel carbs (4 separate floats): https://www.boats.net/catalog/yamaha...jrz/carburetor

When you rebuilt the carbs, did you pull out ALL the JETS, inspect /clean? Also, did you blow cleaner thru all the orifices of the carb body (no obstructions)?

Sounds as if cylinder /carb is not providing fuel. Did you inspect the spark plugs? Is #4 coming out "WET" with fuel, obviously a different color than the rest?


Lastly, what was the initial issue(s) you had?

(Can you post the FULL MODEL # as I'm guessing what you have)?