Mariner 9.9 to 15

A

Abbe

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May 5, 2010
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If anyone knows how to power up Mariner 9.9C from 1981 (Japan) to 15 HP. I've founded that there is difference in reed valve, but besides that, any other differences? what's with carb, ect.?
If anyone knows or have experience with it i would appreciate it.
I know that this engine is Yamaha based, but the oldest part list of yamaha i've founded is from 1984 and it's not the same engine.
Thank you!
 
ONERCBOATER

ONERCBOATER

Chief Petty Officer
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Oct 11, 2010
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Re: Mariner 9.9 to 15

as usual i could be wrong here....
for a johnyrude, the answer is new carb( 15hp is larger bore), reed stop shim, and on some a tuned exhaust pipe (depending on year, later 9.9s had it only the 15s had it in earlier years). The extra 5hp was gained through RPMs/tuning.
for the 9.9 merc i am not sure, but i can almost assure you it won't be just the reed valve.

Sean
 
A

Abbe

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Messages
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Re: Mariner 9.9 to 15

Faztbullet said:
High speed jet and reed stop opening...
Click to expand...

I understand what i got to do with reed stop, but if you could be more detailed about high speed jet. Do i have to change jet and nozzele (whole assembly) or just jet. Thank you!



ONERCBOATER said:
as usual i could be wrong here....
for a johnyrude, the answer is new carb( 15hp is larger bore), reed stop shim, and on some a tuned exhaust pipe (depending on year, later 9.9s had it only the 15s had it in earlier years). The extra 5hp was gained through RPMs/tuning.
for the 9.9 merc i am not sure, but i can almost assure you it won't be just the reed valve.

Sean
Click to expand...

This is not merc engine, it's old yamaha, Mariner produced in Japan
 
Faztbullet

Faztbullet

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15,616
Re: Mariner 9.9 to 15

Open the reed stop to 3.9-4.1 mm for a 15hp as the 9.9hp is set at 1.37-1.65. From what I found the 9.9hp sould have a #88 main jet and the 15hp is a #102. These are MM size so a #88 is .88mm and a #102 is 1.02mm. You can get these at a motorcyle shop as these need to be reamed to size not drilled.
 
A

Abbe

Cadet
Joined
May 5, 2010
Messages
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Re: Mariner 9.9 to 15

Faztbullet said:
Open the reed stop to 3.9-4.1 mm for a 15hp as the 9.9hp is set at 1.37-1.65. From what I found the 9.9hp sould have a #88 main jet and the 15hp is a #102. These are MM size so a #88 is .88mm and a #102 is 1.02mm. You can get these at a motorcyle shop as these need to be reamed to size not drilled.
Click to expand...

one more thing.....some time ago you have answered my question about reed valve clearance:
The reed stop gap for the 9.9 standard is 2.9-3.1mm (0.114-0.122 in)
The reed stop gap for the 9.9 CDI is 1.2-1.4mm (0.047-0.055 in)
The reed stop gap for the 15 is 3.9-4.1mm (0.154-0.161)

when i've disassemble reed valve i've determinated that reed stop gap on my engine is 3mm, that means that my engine is standard..... Now i just wanna make sure that they are no differences in main jet between those two models
 
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