Time to de-carb my 2-stroke Johnson?

After using the boat on a very short trip last night (about 30 minutes of running on plane with very little idling), I found this this morning. It smells like engine exhaust (i.e., carbon). I'm thinking last night's running helped push this out the vent hole.

I've been idling this engine a lot due to using the boat in a river that is all "No Wake." Last weekend, we did a three day trip on the St. Johns that was primarily just going slow so the wife could take photos.

Of the last 25 hours on this engine, I'd venture so say that at least 23 of those have been under 2500 RPM.

I also had to use some Wally-world 2-stroke oil in a pinch last weekend (about a quart)--previously I had been using Penzoil Marine and Quiksilver.

The lower unit lube is clean and fine. My diagnosis for this is carbon buildup in the engine's exhaust. I'm planning on doing the Seafoam treatment.

Thoughts?

 

Good advice, Brett!

Here's a link to the photo. Let me know if any of you all think this is more serious than my diagnosis.

http://www.flickr.com/photos/59745094@N07/7223217022/

 

Sounds good guys!

"Just an OMC doing it's thing."--I love it!

It cracks me up when I go to buy parts for this motor and see that 1984-up take the same parts.

It's loud and smoky, but it does the job.

Thanks again!

 

I pre-mix.

The oil brand switch I did in the last full tank may have contributed, and I've really been spending a lot of time running the motor at low RPMs. As I've researched this issue, I'm finding many people who use a small 2stroke as a kicker for trolling have the same issue (lake fisherman).