2008 9.9 2stroke conversion to 15hp

[rodbolt17]

looks like the biggest difference is the reed stop diminsion.

[almetelo]

Hi!

Thanks for keep us informed and share your experience.
I'm glad you have good results with your extra 5HP.
I guess it must improve to 2kts WOT maximum but on a "small" motor can make even much more diference.
Do you know how many RPM you got more?

Allows me the following if you want the best of your motor. "don't get me wrong"

(if you don't have it yet) get a tach "even a tinny or chinese or cheap tach" and make sure you have the right propeller for your needs.
As you know will make a lot of diference so you can take the best advantage from your motor.
If your sure you have the right propeller I don't belive that will make any diference.

Good luck

[99yam40]

I agree, you need to check to see if the prop on a 15 should be different than the 9.9, and make sure your WOT RPM is getting into the upper end of spec for the motor with the load you are running with

[Hocus-Pocus]

Determining your engine speed is quite important. On that note, I just installed a genuine "Tiny Tach" on my 15MSH. Because I've converted to remote controls I ordered it with 12' leads and the optional filter for multi cylinder. I haven't checked it against my optical tach yet, but I'd be willing to bet that it is very close to being accurate.

There are Chinese knock offs available on E-Bay for about $12 delivered to your door. For that price I bought a couple of them to see what they would be like. Testing on a multi cylinder 4 stroke they were absolutely useless as a tach, might be OK for an hour meter, but that's it. Some time in the not too distant future I will do a side by side test on my 15 and compare to the known accurate optical tach, but at this point, I'd say pay the extra money and go with the genuine Tiny Tach.

[rodbolt17]

biggest issue I see with some inductive tachometers is user error.
not all inductive tachs can operate on a waste spark ign system like most 4 stroke yamaha motors use.
best to check which ign system your motor uses before buying a tach.

[Hocus-Pocus]

Both Tiny Tach and the knock off can be configured for most applications. My testing with both configured for the same application showed the knock off as completely inaccurate. My guess is that Tiny Tach has a factory ordered filter for multi cylinder. The knock of does not. Tiny Tach has a signal and ground wire for sensing. The knock off has only signal. All of this just points to more quality in the original.

Having said all that, the knock off might be just fine with a single cylinder engine where there is less likelihood of external "noise".

[Doneaster]

Hi Rodbolt,
Do you have any experience in setting the Ignition Timing on a 9.9 HP Yamaha? I've read the service manual for my 1997 Model and it indicates that a Dial Indicator is needed to adjust and set the timing. The dial indicator is used to determine the location of the #1 piston .166 BTDC for Advance timing and .005 AFTDC for Retard Timing. Do you know of a better and easier method to adjust the timing without having to use a Dial Indicator?