Converting Yamaha 150 to 200

[David Borg]

can a yamaha 150hp be converted to a 200hp ? do they have the same port timing ?

I already made a research and the differences I could find were carbs, reeds and exhaust

I think its a 2004 model.If it can be done will the timing need to be adjusted?

thanks
David

[Charlie M]

is this a VMax 150? The VMax 150's have the good stuff like horizontal reeds, but I think they have the smaller exhaust ports and not really sure on the carbs but I think they have the good carbs.

[Ray Neudecker]

There was more than one in a carb motor. If is the horizantal reed version it is fairly simple and inexspenive to convert and you retime for performance. The block itself is the 200 porting. Rejetting is also necessary.

[David Borg]

thanks I will have a look at the intake manifold to see if its a horizontal or vertical reed

[4174jm]

Have A Friend That Wants To Do The Same Thing On A Plane 150 Hama 98 Model On An 18` Vip Fish And Ski Would The Performance Gain Be Worth It

[David Borg]

I had a look and its a vertical reed version


Is the conversion possible , if yes what will it take is it worth doing?

thanks
David

[Ray Neudecker]

Yes it is possible. That intake requires replacing the reed plates and carbs. The reeds are blocked on one side in the US 150 and they have 24-26 mm carbs. The 200 reed block assemblies for a vertical intake motor and the carbs off of it or even better the old 220 (V-6 Special) or a 225 (excell) will make a tiger out of the 150.
Some models in the states also gain from a tuner or exhaust divider. The overseas models may have some differences I am not aware of.
Cheapest most reliable hop up for 50 hp I know of for an outboard.

[Sctreeguy]

I know this is a really really old post, but I have a carb 2002 vmax 150 and looking for more performance. Do I look for parts from a excel motor? What all is needed, carbs, reed cage?

[Sctreeguy]

Do I need to change the heads or just the thinner gaskets or cut the heads?

[Markus]

Change heads. 220 Special are the best followed by 225 Excel.

But then you need to run good 93 pump octane fuel.

[Sctreeguy]

What about the other parts?