87 nissan 40hp 2 stroke one cylinder not firing

[Deebo863]

I have a 87 Nissan 40hp 2 stroke that has good compression 120 in both cylinders, has good spark, but the bottom cylinder isn't firing. It is electric start and it fires up on the first push of the button. I will take any suggestions you have on what could be the problem and the fix.

 

[pvanv]

If earlier model than 40C, I have no info, and few if any parts are available. Need actual model, not year.

 

[Deebo863]

If earlier model than 40C, I have no info, and few if any parts are available. Need actual model, not year.

NS40C
361A-1 69775
This is what's on the plate

 

[pvanv]

I take it you have the siamese coil, where there is 1 coil for both cylinders. So the issue must be fuel or a plug.

 

[Deebo863]

I take it you have the siamese coil, where there is 1 coil for both cylinders. So the issue must be fuel or a plug.

I put a new fuel pump on it and I cleaned the carb. It starts right up. Gas is going into the cylinder.

 

[Deebo863]

I put a new fuel pump on it and I cleaned the carb. It starts right up. Gas is going into the cylinder.

I've also switched the spark plugs and wires from top cylinder to bottom cylinder and the bottom still doesn't fire up

 

[pvanv]

What method did you use to clean the carb?

 

[Deebo863]

What method did you use to clean the carb?

Carb cleaner

 

[pvanv]

Probably not aggressive enough. Use real carb dip overnight, preferable in a heated ultrasonic tank. Then carb cleaner liberally to dislodge what was softened overnight.

 

[Deebo863]

Ok, thanks I'll try that.

 

[Deebo863]

So I have both cylinders running, but when I pull off either cylinder spark plug wire the motor doesn't shut off. It keeps running on one cylinder. I've never had that happen before, everything I've read says the motor should shut off if you pull the spark plug wire from either cylinder. Have you ever seen or heard of this?

 

[pvanv]

Normal.