DF carb issues

[MGrant58]

I have a DF15 I bought new in 2006. Motor has less than 100 hrs on it, and had not been started in nearly two years.
This morning I decided to start it. Checked the oil and plugs. Plugs looked fine. Then mixed one gal fresh gas with app. one half can Seafoam. After a half dozen pulls the motor started. It now runs well at idle and up to half throttle, then starts breaking down when I advance the throttle any further.
Could this be something as simple as needing a new fuel filter and/or plugs, or do you think the issue is in the carb? I'm hoping the Seafoam sitting in the carb for a day or so will dissolve anything in the high speed jet, providing this is where the problem might be.

Any input is greatly appreciated.

Thanks in advance,
Mike

[bklake]

Edit. I reread your post. Was the engine in Neutral? That was the rev limiter kicking in at 3000 RPM. Completely normal. If it was in gear, keep reading.

I have a DF25, same year, that did the same thing. I believe the carbs are very similar. Long story, short, you will have to remove the carb for cleaning. There is a jet, can't recall the exact name right now, but I call it the mid range jet. It is probably clogged. This jet is under a rubber cap and is easily overlooked. There are three jets total. I used a nylon bristle from a scrub brush to clean the jet. Normal soaking will not get the gunk out. Visually verify that you can see through the jet before you put it back in. Do not use anything metal to clean the jets or you will damage them.

The design allows fuel to pool in this Mid jet. It never gets emptied out even if you run the carb dry before putting the motor away. That little bit of fuel evaporates and clogs the jet. The engine will idle great but won't accelerate past about 2000 RPM.

I could not find a rebuild kit for my carb. Only individual parts. I forgot which gaskets I got but probably the bowl gasket and top plate gasket. These gaskets are rubber and if in descent condition, probably won't need to be replaced. I can only get gas with ethanol and found one of the originals to be swollen. The replacement went through several tear downs and is holding fine to this day. New ones may be upgraded material. It took me a few tries to find the problem.

Before this, I never worked on a carb this extensively (and have it work correctly ever again), I never touched a Suzuki carb. With the help of the factory manual, I had it off, apart, cleaned and reinstalled in about 2 hours. It is a marvel of simplicity.

[MGrant58]

Thanks for the reply.
Yes, it was in neutral. I will try it in gear and let you know how it goes.
And thanks also for the tips in case it is a carb issue.

Mike in Maine

[plumbertom]

Edit. I reread your post. Was the engine in Neutral? That was the rev limiter kicking in at 3000 RPM. Completely normal. If it was in gear, keep reading.

I have a DF25, same year, that did the same thing. I believe the carbs are very similar. Long story, short, you will have to remove the carb for cleaning. There is a jet, can't recall the exact name right now, but I call it the mid range jet. It is probably clogged. This jet is under a rubber cap and is easily overlooked. There are three jets total. I used a nylon bristle from a scrub brush to clean the jet. Normal soaking will not get the gunk out. Visually verify that you can see through the jet before you put it back in. Do not use anything metal to clean the jets or you will damage them.

The design allows fuel to pool in this Mid jet. It never gets emptied out even if you run the carb dry before putting the motor away. That little bit of fuel evaporates and clogs the jet. The engine will idle great but won't accelerate past about 2000 RPM.

I could not find a rebuild kit for my carb. Only individual parts. I forgot which gaskets I got but probably the bowl gasket and top plate gasket. These gaskets are rubber and if in descent condition, probably won't need to be replaced. I can only get gas with ethanol and found one of the originals to be swollen. The replacement went through several tear downs and is holding fine to this day. New ones may be upgraded material. It took me a few tries to find the problem.

Before this, I never worked on a carb this extensively (and have it work correctly ever again), I never touched a Suzuki carb. With the help of the factory manual, I had it off, apart, cleaned and reinstalled in about 2 hours. It is a marvel of simplicity.

you and I have the same motor.
Where did you locate the individual parts?
The Sierra kit for those Mikuni carbs is 18-7773 by the way.