I live near Rocky Mount VA and unfortunately there are no Suzuki dealers in my area. This engine was professionally winterized & fogged last year. The thing starts and idles great but when I try to rev it up, it won't go above 2200-2500 RPM's, it gags & falters. Fresh gas with Sea Foam added, primer bulb pumps up tight, new plugs gapped @ .035, new fuel filter, fuel pump can squirt further than I can, had the carb apart 3 times, removing all removable jets & valves checking for blockage. Soaked with cleaner then blew it out with air. Carburetor pump, needle, seat and float ok. Started it up with the gas & Sea Foam mix, shut it down then let it sit overnight. Same thing the next day.
I first thought it was fuel/carb problems but after removing the new plugs I found them both to be sooty and damp. Coil, CDI, magneto? Any back-yard gurus out there? Any peculiarities known about these engines, common known problems or failures?

I have a Yamaha 250 hpdi I know its alot bigger but I had the same problem and I couldn't pin point it.Ended up being the coils not putting out enough spark, had some spark just not enough.Hit the gas it would die like starving for fuel, just a suggestion.

LIKE 5Bigns SAID,POSSIBLE LOW SPARK,HAVE SEEN IN THE PAST WHEN THE FACTORY PAINTS THE ENGINE,THE PAINT WOULD BE SO THICK THAT THE COIL WOULD NOT MAKE A GOOD GROUND TO ENGINE BLOCK,ALSO THE COIL GROUND WIRE LOCATION,JUST A THOUGHT? 4 STROKES DONT NEED OIL MIX WITH GAS,TOO MUCH AND THE FUEL MIX WILL BE TOO RICH(CANT BURN PROPERLY).COUPLE OF OTHER THINGS TO LOOK AT WOULD BE THE TIMING KEY UNDER THE FLYWHEEL,ALSO CHECK OIL LEVEL IN CRANK CASE, MAKE SURE IT IS NOT WAY TOO FULL,THESE ARE JUST A FEW THINGS TO QUIK CHECK,I HOPE ONE HELPS,ANTHONY......

Try marine doctor .com with your question, they seem to be very helpful.

When I first got this engine I tried it on the boat. Max RPM was 2200-2500 as previously stated. I removed the engine mounted it on/in a barrel and fired it up, same problem. I since removed and cleaned the carburetor, same problem. Finally got to talk to a certified Suzi mechanic today. He told me the engine had a limiter switch that would prevent it from revving much over 2200 rpm in neutral. Sure enough. Its mounted on the port side of the block with the button riding against a nylon cam that's attached to the shift lever linkage, looks like an auto brake light switch. Switch is on in neutral, off in either F or R. Guess what. I was running it in neutral.
I started the engine, loosened the switch mounting screw and rotated the switch so the engine would "think" it was in gear. The little bugger revved up just fine. DUH!
The carb was blocked and I apparently fixed it the first time around, just didn't know it because of running it in neutral in the barrel.
I do appreciate your suggestions and willingness to help.
On the positive side maybe this info will help someone else with either a Johnson or Suzuki 9.9/15 4-stroke that won't rev up. (Could be a bad/disconnected safety switch or maybe they just need to kick it into gear).

JD East of Roanoke on RT 24 turn left in Stewartsville go about 2 miles there is a man that I think is tops and he does not charge a arm and a leg. He has helped me 3 times on different problems Danneys Boat Shop Phone 890-1034 Are you the JD that goes to Bonsack Baptist Church?

Thanks for the info Bill, I'll give him a call. No I'm not the same JD. I live in Rocky Mount, VA. I do have a big ugly cousin who lives in Bonsack. A lot of people say we look alike, almost like brothers.
Thanks again.

JD , just happy to see another franklin county man on here.I'm "stationed" in Burnt Chimney.

shaddaddi, me too. I felt like the Lone Ranger until you showed up. I only go to Kerr 3-4 times a year but still like to hear about others catching them. There's a lot of nice, friendly & knowledgeable people on this site. You tearing up the Stripers on SML? I usually don't fish SML during the Summer months. Too many crazies out there.

too many crazies for me also.I hit a few night trips in the summer.