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Old 14 June 2008, 20:17   #1
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Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
Tohatsu 18 HP 2 Strokes Inquiry

Hello all...

Need a very precise answer, so Ribbneters that does not have this precise engine please stay away from helping as you probably won't have the correct answer.

If your engine is mounted on boat on top of a trailer, stand behing engine, remove cowl and turn engine completely counter clockwise until stops. With left hand begin to turn throttle grip very slow but firm until you see the wot butterfly stopper flat against the carb body (pic 1) Stop acelerating, at this point the throthle stopper arm has not reach it's screw stop position and still with some more mm for the throttle arm to fully accelerate counter clockwise.

Would like to know: What is the position of the stopped roller (pic 2) once the pic 1 condition is reached, is it at the beggining(1) on the curve (2), or at the angle edge(3). See pics for better comprehension & answer.

Other brand engines like Evinrude use plastic cams and a screw at the left side to adjust better the max wot (butterfly) adjustment. Toh uses a metal cam with out the final screw. Seems all 18 engines are comming factory delivered so that the wot position is obtained around the beginning or angle edge and not at the furhter left side of the cam. This is placing unnecessary excesive stress on different carb parts that will wear out much faster with time, poor oiling and prolonged engine near or constant wot acceleration speeds (pic 3)

So for my peace of mind have modified the vertical rod adjustment height to obtain total wot at the furthest left side of the cam with 1mm of total roller over actuation. Have obtained also a much better little longer final acceleration range compared to the shorter acceleration range as before. The engine is running perfect and smooth specially at wot.

Happy Boating
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Old 18 June 2008, 22:27   #2
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Country: Australia
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Boat name: Duck Tales
Make: Mercury-Quicksilver
Length: 3m +
Engine: 18hp Tohatsu
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hola,

i have read your post numerous times to make sure i really understand the question. after studying the pictures, the answer is, when the stopper is against the carb body, the roller in my outboard is on the angle edge.
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Old 20 June 2008, 11:37   #3
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Country: Other
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Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
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Quote:
Originally Posted by Clipper View Post
hola,

i have read your post numerous times to make sure i really understand the question. after studying the pictures, the answer is, when the stopper is against the carb body, the roller in my outboard is on the angle edge.
Hola Jack, thanks for the answer & time

I assumed it was close the angle edge, at this point you still have some more throthle grip to turn CCW. Last issue, when accelerating to this point (roller/angle edge/wot position, allegedly wil have reached top end speed)

If accelerating the throttle arm to full CCW, will you feel /see the supposed extra speed gainned difference untill the throttle arm accelerates no more (has reached final end arm stop position) ?

Or there's not much speed difference between both positions ? As incledible & bizzare as it looks the service manual doesn't mention a word on how to adjust cam/roller/rod timing procedure after stripping down the carb for maintenance. Only the form to take off the carb from the crank case. Who understands these Japs. But there is Rinbet to resort.

Next time you go out boating, make a throttle test run to compare. Would like to hear about what you concluded.

Happy Boating
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