Low RPMs in starboard engine

[MOA_Chaser]

I had my SX230 out all three days this weekend. I had done an oil/spark plug change before running her this year and everything went well. Except, my starboard side engine is running low RPMs. It sounds fine... it only gets up to about 8.9k while the port engine gets to around 10.5k at WOT.

I went back and forth and cut the engines while listening to the tone and, to me, it sounds like the RPMs on the tach match what the engines are doing (at least from the note the engines are giving off). I just have to give more throttle to the starboard engine to get it to match the port engine, and of course my throttle levers don't match like they used to and I run out of throttle.

Any ideas on where I can start with this one?

 

[mark_m]

I had my SX230 out all three days this weekend. I had done an oil/spark plug change before running her this year and everything went well. Except, my starboard side engine is running low RPMs. It sounds fine... it only gets up to about 8.9k while the port engine gets to around 10.5k at WOT.

I went back and forth and cut the engines while listening to the tone and, to me, it sounds like the RPMs on the tach match what the engines are doing (at least from the note the engines are giving off). I just have to give more throttle to the starboard engine to get it to match the port engine, and of course my throttle levers don't match like they used to and I run out of throttle.

Any ideas on where I can start with this one?

Check to make sure you connected all of the plugs up. My first time out this year I left #4 unplugged on the starboard engine and had similar experience.

 

[MOA_Chaser]

I'll do that... I thought I'd hear a "miss" or something if a plug wasn't firing! That's something if it runs that smoothly with only three cylinders firing.

 

[mark_m]

Check to make sure you connected all of the plugs up. My first time out this year I left #4 unplugged on the starboard engine and had similar experience.

I would get to about 8500 on the motor with three plugs.... As a point of comparison

 

[mark_m]

I'll do that... I thought I'd hear a "miss" or something if a plug wasn't firing! That's something if it runs that smoothly with only three cylinders firing.

Right! It just sounded little muffled at wot. Idle/ no wake was same sound& behavior for me. I thought I had stretched a throttle cable or something coming out of winter storage. On the water I reconnected the cylinder and was good to go

 

[scokill]

In addition to making sure all cylinder's coil packs are plugged in, I would make sure all were seated. Coil pack could be bad in one cylinder. You could check by swapping out with the other engine and then testing back on the lake. You could also check the throttle cable. Pull air filter cover, air filter, flame arrestors, and check throttle cable adjustment. Push throttles all the way forward and see if you have any throttle left at the throttle plate. If so, you can adjust out as there are two nuts that you can loosen/tighten. I also recall someone changing plugs, having your issue, and changing them all out again with different new plugs and the problem going away....