Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

[keith23464]

I have been reading some of the other threads and have not seen my model addressed. IS it a simple cam or throttle swapout?

 

[keith23464]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

I am just trying to get a bit more power out of it. It also has a stock prop. Is there an upgrade prop that might help as well?

 

[TGuy]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

On the 4-strokes it's not a simple cam like some of their old 2-stroke models. I'm pretty sure the entire carburetor is different and there may be other parts involved as well. Paul at this forum can tell you for sure but it won't be a simple $20 part As far as the prop goes, before you can determine if the prop needs to be changed you need to know what RPM's you're turning now. Need to hook up a tach to your motor and see if you're even close to the max RPM range of your motor. If not, then changing prop pitches could definitely help. If you're not hitting the maximum RPM's, you're not getting the max. horsepower

 

[keith23464]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

DO you know how to get a tach on a motor that does not have tach built in ?From what I have read, I really need to be in the water to get this reading right?

 

[TOHATSU GURU]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

I have been reading some of the other threads and have not seen my model addressed. IS it a simple cam or throttle swapout?

Just a carburetor difference.

 

[TOHATSU GURU]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

Just buy a Tohatsu tach.

 

[keith23464]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

Do you know what carburetor is the correct one? Is that a difficult install? Anything else that needs to be done? Like a retiming?

 

[pvanv]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

Start with a Factory service manual:
SERVICE MANUAL - TOHATSU - 9.9/15/18 A&B 4STR Covers 9.9hp, 15hp, 18hp "A" & "B" 4-stroke models Part# 003-21041-0 $40.00

Order a carburetor:
3R3035002M CARBURETOR ASSY, 15A-B 4-STROKE $216.77

Add on a tachometer so you can dial in the correct prop:
TACHOMETER - 4-STROKE MODELS - BLACK FACE Part# 3AC726400M $74.25
or
TACHOMETER - 4-STROKE MODELS - WHITE FACE Part# 3AD726400M $74.25

Grab a wiring harness for the tach:
361725390M LEAD WIRE TACH 20' $44.40 for tiller models
or
3R0725371M LEAD WIRE, METER $56.13 for remote models

The carb swap is 2 bolts (and associated ABS wiring, and gas line). Timing is set by the CD module, and not adjustable. There are a bunch of props available (even 4-blade units). See what your WOT RPM is (yes, you must be on the boat, loaded as usual, in the water to test), and then you can decide if you want a different prop. Any dealer (including me) can set you up.

 

[TOHATSU GURU]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

Do you know what carburetor is the correct one? Is that a difficult install? Anything else that needs to be done? Like a retiming?

3R3032001M

No

No

 

[pvanv]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

3R3032001M

No

No

3R3032001M is superceded to 3R3035002M

 

[keith23464]

Re: Can I upgrade a 2003 Tohatsu 4 stoke 9.9 (MFS 9.9B2) to 15HP?

Thank you for all of the information!