OS 9 b

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Use a little silicon. Then look through the front case towards the carb once it's dry to make sure none of the silicon has squished out and is impeding flow. If it does, let it dry and cut the excess out with a hobby knife. I have seen several guys have lean issues due to air leaks mating the 9B to the CMB and a little smear of silicone makes it happy.

I also have found that taking a round needle file and slightly opening up the mounting holes on the 9B towards the outside seems to make getting the screws started easier. All my motors have the cast front case so maybe the billet ones you don't have to do all this stuff.
 
Use a little silicon. Then look through the front case towards the carb once it's dry to make sure none of the silicon has squished out and is impeding flow. If it does, let it dry and cut the excess out with a hobby knife. I have seen several guys have lean issues due to air leaks mating the 9B to the CMB and a little smear of silicone makes it happy.

I also have found that taking a round needle file and slightly opening up the mounting holes on the 9B towards the outside seems to make getting the screws started easier. All my motors have the cast front case so maybe the billet ones you don't have to do all this stuff.
Thanks Mike, thought it had to be tweaked with a rat tail file. Just was not sure between the cast and billet housings............==={}
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Since the fuel circuit runs from the high speed to the low speed needle you take the low speed out of the equasion to the rich side. You will have to keep the motor pretty well wound up until it the boat is launched. Get the high speed dialed in. Then start leaning the low speed on the boat stand (the motor has to be warm) until you have a reliable idle (w/the carb opened about 1 cm) and the the motor will snap right up.

Too lean and the motor at idle will speed up and the pipe will sound raspy and hollow. Too rich and the motor will kind of blubber, the idle will drop off and it will die.

A good tip for tuning the low speed on an OS9B is to find a hex bit that fits the low speed adjustment screw well and then slide a small, coarse Dremel sanding drum over the bit.
 
Ray,

To answer your original question... the masses will tell you it fits... use a caliper, and you will see, it needs some minor 'fit' adjustments to fit/seal correctly.... ie. Minor slotting (from memory about .015" per side), and/or you can use silicone as other have suggested to 'compensate for that minor miss-fit, depending on your finesse, and torqueing ability... The proper way is to use a caliper to verify bolt spacing on the CMB housing and compare that to the C/L bolt spacing on the OS 9B. The 'inset' bore (Boss on the 9B) is a close fit, and aligns well.

As far as the fuel needles are concerned, I think the 'text book # for the .67 GH are about 2 1/2 turns out on the low-speed when the barrel is completely closed, and about 1 5/8 turn on the high-speed if memory serves me correct, to run like a rocket with a short pipe.. Some may run leaner on the H/S.

Bottom line, make sure the carb mates up properly (eliminate the potential leaks) and the carb will work well.

DJ
 
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Ray,

To answer your original question... the masses will tell you it fits... use a caliper, and you will see, it needs some minor 'fit' adjustments to fit/seal correctly.... ie. Minor slotting (from memory about .015" per side), and/or you can use silicone as other have suggested to 'compensate for that minor miss-fit, depending on your finesse, and torqueing ability... The proper way is to use a caliper to verify bolt spacing on the CMB housing and compare that to the C/L bolt spacing on the OS 9B. The 'inset' bore (Boss on the 9B) is a close fit, and aligns well.

As far as the fuel needles are concerned, I think the 'text book # for the .67 GH are about 2 1/2 turns out on the low-speed when the barrel is completely closed, and about 1 5/8 turn on the high-speed if memory serves me correct, to run like a rocket with a short pipe.. Some may run leaner on the H/S.

Bottom line, make sure the carb mates up properly (eliminate the potential leaks) and the carb will work well.

DJ
Dave, it was .010 per side. With O-ring seals well, I hate using silicone on anything. Thanks for needle settings.
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Ray, there is a product you might want to try. It is called Dow Corning 111. It is a non-hardening silicone developed for lubing and helping seal O- rings. Kind of a thick clear goo that will not harden and is good to 500F. A 6.6 Oz. tube was around $13.00 last time I checked.

Glenn
 
The low speed needle is on the opposite side of the carb as the high speed needle. It is a small common head screw.
 
The side with the throttle linkage on it. May be hard to see with the motor installed.
 
That is not a drain screw on the bottom
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. Leave it alone or put it in with blue Loctite.
 
Best case scenario is have a motor that can be pulled and replaced quickly. I'll send a P.M. Michael
 
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