1986 Yamaha V6 Tuning ???

[MonkeyButler]

I have a new to me '86 Yamaha V6 2596cc which I belive is the "Special" model mounted on a Wellcraft 250 Sportsman. The model is 6VSPCXJ and it has Nikki carbs on it. I'm going to rebuild the carbs because of a midrange bog and I have a few questions about tuning this thing.

First off, what is the horsepower on this, 200 or 220? I thought it was a 220 but a few people have said it's a 200. The reason I ask is because my Seloc manual list the tune up specs by HP, not model. For the 200 the pilot screw setting is 1-1/8 to 1-5/8 turns and for the 220 it's 1-1/8 to 1-3/8 port side and 1/2-1 starboard.

Second (dumb) question, which side is port and which is starboard? I just want to mafe sure; is it facing the carbs or vice versa? That 1/2 to 1 turns seems odd. If I start at 3/4 turn how would I tell if it's off, by performance or reading plugs?

Last question, I promise. The prop that came with it appears to be a 15" diameter and is marked 17M. Is that the pitch? I can easily get 5800RPM and 34MPH with about 3/4 throttle. I haven't pushed it past there. I'm guessing the boat weighs around 4000lbs as tested and might be up to 1000lbs. more heavily loaded. Can someone give me some prop advice or point me in the right direction?

I know it's a lot to ask. Thank You in advance.

Steve P.

 

[Ray Neudecker]

Re: 1986 Yamaha V6 Tuning ???

The engine was a 220. It does require premium fuel. Rebuild the carbs with the new needle and seat as well as bowl gasket. Do away with the fuel disconnect and the engine mounted filter. Make sure you have a good in line water seperator.
Starboard is to the right facing the bow of the boat, port to the left. Sounds like you may need more prop. A wide open throttle test to determine max RPM's with the present one gives a bench mark to go by. That unit had a 1.72 /1 gear ratio.