2003 Yamaha 115 HP 2 cycle stalls at idle

I'm new to the forum but have read several posts in the past and successfully used some of the advise given. Thanks in advance.
I purchased a used Sea Hunt 186 with a Yamaha 115 2 stroke both 2003 at the end of last year and launched on Saturday Jun 6 2015, with fresh high test gas. Motor runs fine above 1500 RPM but stalls below 1200 and will not come to idle. Starting it at high rev then putting into gear the motor stalls. We got in ok but was a little nerve wracking. Also burned 10 gallons in about an hours and a half cruising at around 1500 to 2000 RPS inside water way. Basically going slow not on plane. Water separator filter has been replaced, fuel filter emptied and screen cleaned, new plugs gaped at .039. Going to look at the idle mix adjustments 5/8s. Any and all comments would greatly be appreciated.

fisherman421 said:

I'm new to the forum but have read several posts in the past and successfully used some of the advise given. Thanks in advance.
I purchased a used Sea Hunt 186 with a Yamaha 115 2 stroke both 2003 at the end of last year and launched on Saturday Jun 6 2015, with fresh high test gas. Motor runs fine above 1500 RPM but stalls below 1200 and will not come to idle. Starting it at high rev then putting into gear the motor stalls. We got in ok but was a little nerve wracking. Also burned 10 gallons in about an hours and a half cruising at around 1500 to 2000 RPS inside water way. Basically going slow not on plane. Water separator filter has been replaced, fuel filter emptied and screen cleaned, new plugs gaped at .039. Going to look at the idle mix adjustments 5/8s. Any and all comments would greatly be appreciated.

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OLD POST:
trying to reach out to everyone that has carb issues on the 1980's thru early 2000's Yamaha 2 stroke v4 115. HOPEFULLY this will help any future owners figuring out what their carb issue is. It took me quite some messing around, trial and error, etc., to figure this out.

I finally narrowed the poor idle, bog, stalling, issue. The below process is ONLY for LOW SPEED. If you have mid or top end bog, you have clogged main jets! They are found in the fuel bowl (bottom of carb) area. This how to will NOT cover mid/top end bog.

SIMPLE HOW TO:
On the top of each carb you'll see TWO brass plugs. These must be removed, as well as the idle mixture screws (2 on each carb). Under teh brass plugs you will see FOUR small holes in each open area. I use a small welding rod tip to clean each opening. Be careful. Spray carb cleaner or similar to aid in cleaning.
NEXT, at the opening where the choke butterflies are, on TOP you will see TWO jets. These must be removed and cleaned. I also use a welding rod tip to clean out the junk. Spray carb cleaner as well.

Reassemble. Factory calls for 5/8 turns out on each mixture screw.

I battled the "lean sneeze" carb backfire/stall issue for quite some time. Finally figured out which part of the carb controlled LOW SPEED/IDLE.
Lean sneeze is where you hear a pop in the carb area when idling. Sometime the motor would stall, sometimes not. Seemed to run better on partial choke.

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Now if you have a bog when going to full throttle or mid range, you likely have a main jet(s) that are clogged. They are located at the LOWER end of the carbs. OTHER ISSUES CAN BE: clogged fuel filter, weak fuel pump, collapsed fuel line/internal part of fuel line. ALL of which I had replaced when I was trying to figure stuff out.

I must say that these yamaha carbs have been the most finicky carbs I've ever owned. They seem like they constantly get gummed up with old fuel. ANd I use E0 - non ethanol. Sometimes seems I'm wasting my time with E0. The good news is, I can have both carbs out, cleaned, and re-installed in just over an hour.

Hope this brief HOW TO helps folks.