Tohatsu 9.9 d2 ignition timing

[ct1762@gmail.com]

those 18's are complete animals! got one that sat since 2001 a couple years back for $150. thing was ALMOST seized, but let her soak in some oil and carefully freed her up. mouse chewed CDI wires, so got a new one. New impeller, carb clean , t stat. thing starts 1st pull, and is more powerful than anything in its class by a long sea mile. im guessing these little beasts put out well over 20hp. congrats!

 

[Branchtree]

Hey guys!

So I finally got the 18 and tested it yesterday.
I gained 1.5 knots (from 20 to 21.5), a bit disappointing.
Same boat, tubes inflated and checked and same weight.

The 9.9hp (15) had a 8.5 prop and the 18 has a 9.
Revs at WOT was 5700 on the 18.

Any ideas?
Check compression?
Change prop?

Kind regards
Per

 

[Sea Rider]

Hey guys!

So I finally got the 18 and tested it yesterday.
I gained 1.5 knots (from 20 to 21.5), a bit disappointing.
Same boat, tubes inflated and checked and same weight.

The 9.9hp (15) had a 8.5 prop and the 18 has a 9.
Revs at WOT was 5700 on the 18.

Any ideas?
Check compression?
Change prop?

Kind regards
Per

With motor trimmed to 90 deg with said 18 HP, does the water flow skims right under the upper small plate as seen in previous post 17 ? If so, check if possible to install the 8.5 15 HP prop to bump wot revs bit higher. Should see + 200-300 wot revs increase with + 0.5 pitch. Don't know if will gain a slight top speed increase from previous achieved 21.5 knots, but definitely will better the hole shot from a dead stop when at full throttle...

Happy Boating​