1986 Yamaha 30hp (Mariner) Manuals??

[surfcaster]

I bought this 86' 30hp Mariner engine, ordered the Seloc Mariner manual that covers 2 - 60hp 2 stroke models....It wasn't long before I discovered that based on S# it's actually totally made in Japan by Yamaha....The illustrations in the Seloc match my engine except that the spark plug gaps show .024 for the Mariner and .035-.039 for Yamaha (spec from 86' Yam owners manual).

I replaced fuel pump, removed and cleaned carb, new tank, new hose and bulb so fuel should not be an issue. Mariner manual says carb "J" does not have air/fuel mixture adjustment....

The only problem is that it won't plane out properly, seems to sputter a little on high end....cavitation problem?? This is with 2 people, minimal gear. We hit 19.6 mph per gps at one time but 16 mph was more common.

Setup;
1986 Aluma-Weld 1442, 65" on top in rear, Semi V, flotation added..
30hp, manual trim, stainless prop (don't know pitch)

[99yam40]

I would guess it is still a fuel problem if it is sputtering .
My c40 had a problem with dropping cylinders at high RPM until I found out someone had drilled out the main jets, ran fine at other rmp.

[surfcaster]

I guess I could go ahead with a carb kit install and clean it a little better. When I worked on it before all I did was clean the main inlet (that was completely blocked) ,needle valve, drain screw and bowl. The float and gasket looked a little rough but intact....I just don't want replace parts that are functional just to replace them.

What about the plug gap on Yam vs Mariner specs....my S# is 689 s ***XX, block has the Yam logo right on it.

Took her out yesterday and she sputtered a little a couple of times and always at full throttle. Died once at idle, always cranks right back up.

Thanks,

[surfcaster]

Does anyone have knowledge of what I'm asking here? I guess it's just not that easy to fix a 24 yr old engine....