First Tohatsu motor 9.9HP

andreipou

Petty Officer 1st Class
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Nov 26, 2008
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246
Put top arm back to 72 mm.
Had to extend lower arm from 75 to 77 mm to achieve +22 to -3 degrees.
Put stop screws as you said.

First pic is max open throttle.
Second is max closed. Roller is still sitting on low step of the cam
 

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gman2692

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Nov 16, 2021
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My motor looks just like that and is 9.9b2. Mine is 1986 if that helps you in any way
 

Sea Rider

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Sep 20, 2008
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Where did you got the measurements for both horizontal and vertical arms ? Clarify : did you played with stopper A to achieve 22 deg as posted, or achieved that seeting playing witht he vertical arm ? this is important to know.

Seems you got both cam/carb's roller settings mixed up. In pic 1 the carb's pawl needs to sit flat against the base as seen in second pic, post 60, once there and without releasing the pawl located on the metal plate extreme readjust the roller arm screw for the roller to sit against the high hill cam portion and that's with throttle grip set to max throttle. Something like this, this cam/roller synch pic corresponds to a 9.9 D2 motor : Is the cam same as yours ?

9.9 D2 Cam-Roller  Snch.JPG

Once there, when returning the grip to min throttle, should see the roller stopping at the beginning of the cam, that's where the carb works on its own, readjust and report...

Happy Boating
 
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andreipou

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My motor looks just like that and is 9.9b2. Mine is 1986 if that helps you in any way
Do you have any manual that covers B2 model?
I wonder if older B2 model has differences that cause all this headache.
 
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andreipou

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Nov 26, 2008
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I got measurements from the manual (pic 1 & 2), but it does not cover B2 model what could be the problem. I was not able to locate B2 manual.

I had to play with arm length to achieve -3 to +22 range. It is as much as tiller arm can rotate in both directions now. Stopper screws are not even needed really.
With default arm lengths range would be 0 to +20 only.

My cam looks differently (pic 3).
Do you mind posting side pics of carb showing throttle and cam position with tiller to max and tiller to min?
 

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andreipou

Petty Officer 1st Class
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Nov 26, 2008
Messages
246
My motor looks just like that and is 9.9b2. Mine is 1986 if that helps you in any way
gman2692, if you do not have B2 manual do you mind checking what is the range of timing marks from MIN to MAX tiller turns?
Is it -3 to +22 ( see pics from SeaRider post #56) how to check it?
Also, what is the length of vertical and horizontal linkage arms measured from center of the pivot balls?
If you can post side pics of carb showing throttle and cam roller at MIN and MAX tiller twist it would be great.
I am getting impression that B2 is not 100% the same as later models, therefore it is difficult to figure out those things.
Tnx.
 

Sea Rider

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Sorry, as stated I'm not familiar with the 9.9 B2 obsolete model. Need to know what the factory specs are for both arms to achieve a spot on time advance/carb synch, surely differs much from the later 9.9 models. The posted pic seen on post 63 shows max timing advance along max cam advance achieved with throttle grip fully turned to max, the pic seems to correspond to a 9.9 D2 model ?

Happy Boating
 
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