Re: Coverting 2000 two stroke Johnson 9.9 hp to 15 hp

Posted by Chuck (209.131.253.130) on January 07, 2004 at 12:32:16:

In Reply to: Coverting 2000 two stroke Johnson 9.9 hp to 15 hp posted by John on December 18, 2003 at 20:36:37:

Check the block cubic inches for the 2000 9.9 and the 15 HP Johnsons. I believe you will find them to be two different motors. If so, the 9.9 cannot be converted.

Early Johnson 9.5's could be converted to 15's by changing the carb's and exhaust tuning insert under the head(more critical than you might think. Early Mariner's, Evinrudes could also be converted.

I think somewhere around 1998-99 the mfg's started changing the motors.

Yamaha two-stroke 9.9's may be the only one you can still convert.

Also, check out Nissan/Tohatsu. Their conversion is very simple one and boosts the output of their 9.9 to nearly 18 hp...the quickest Super 10 on the lake, by far.

Again compare block sizes ask your dealer because things can change fast in the outboard industry.