DT 90 1994 - no fuel to top left cylinder

[fishojs]

Hi all, I have just purchased a DT90 and notice that the top left cylinder is not firing,
I have checked the spark and it is fine, compression across all cylinders is even at 105
there is no difference when I remove the plug lead when the motor is running
I have removed the jet from the side of the carby and cleaned it (it was not dirty) replaced it and the problem persists.
I am not very familiar with these motors, and I would any assistance you could think of.
regards
John

[Solarman]

Try squirting a little gas & oil mix in throat of carb while running on other three cylinders. If it fires up, you'll probably have to soak that carb in carb cleaner then blow out all the little passages and reset everything back to Suzuki manual specs. Do not mix jets/ parts up between carbs, or sides of double carbs.

Also, make sure the spark plug is good. Have bought new plugs and spent hours tracking down a bad plug.

Good luck, post back when able to let us know how it's going.

[fishojs]

Thank you Solarman, I sprayed fuel in the carby and that saw an increase in revs, so I removed the carby and checked the rest of the internal jets, none appeared blocked, but I soaked the carby and then blew out all jets.
I am not sure what the problem was, but it is fixed now and running on all 4.

I was thinking of trying to tune the carbys with a vacuum gauge, but I am not sure where to connect it to each carby, I guess four gauges would be better, but I only have one, how do you think I would go?

[Solarman]

Don't do that. Using vac gauges is not needed. You set the air-mixture screws (all carbs) identically, at what the manual for your motor says. Then leave them alone. The throttle valve sensor, gear counting coil, and rest of electronics do the rest.
You put oil and gas in (with seafoam -for ethanol- in each tank full, or other additive), keep the impeller wet every time motor is started, do the normal maintenance.
And don't let sit for too long. These motors need to be run often to stay in shape. This keeps the internals lubricated, and moisture problems down as much as possible.
Occasionally, you can look at plugs to see if all are burning clean (this will tell you if carbs are adjusted good).

Good luck, post back if need. Happy motoring.