Re: 1966 9.5hp need help
You might want to try adjusting your carb first. Check Joe's excellent article at
http://forums.iboats.com/showthread.php?t=167352. My 71 9.5 had trouble idling with the proper gas/air mixture because the slow speed mixture was too rich, which causes the plugs to load up. Just turning the slow speed needle jet knob on the front of the engine in to the right is how to adjust it to lean it out. Also, if you're not aware, there's an idle speed adjustment on the tiller handle you can turn clockwise to increase idle speed. Note this is different than slow speed needle jet adjustment. When it dies, it is dying becuase it doesn't have enough engine rpm or does it die because it coughs? If it's just rpm, that's easy to fix.
See if it's better or worse when you pull the choke. If worse, that means the mixture is already too rich, so it's getting plenty of gas at slow speeds, so you need to lean it out. Start with the slow speed adjustment needle. Keep in mind those slow speed adjustment needles wear out with age, so you may need to turn it out 1/2 a turn from lightly seating to get it to idle clean.
If it gets better at idle when you pull the choke, that means it's too lean. See if turn the slow speed mixture knob out (counter-clockwise) makes it better as you richen the slow speed mixture. Hopefully this will help you in determining where the problem is.
If it's too lean at idle, that means it's likely the slow speed ports are clogged. You'll need to pull the carb and float chamber base off to rebuild it like samo says. It's a real simple carb though. For some pics of a 71 9.5 HP carb, see
http://forums.iboats.com/showthread.php?t=213715.
If it's sat for 1 - 2 years, it's likely needs carb attention. Also, see if pumping the fuel line bulb helps it to run when you hit the gas on the water - if it helps, that means fuel pump needs to be replaced. You might want to also read the thread I used to resolve issues with my motor at
http://forums.iboats.com/showthread.php?t=211165. To check compression, you'll need a compression gauge, about $20 from a auto parts shop, but get the kind you screw into the head. Your motor needs to be at least 60 psi, with no more than 10 - 15% difference between the two cylinders.
The 9.5's do have a shear pin behind the prop and that's likely the problem. Screw the propeller nut off after removing the cotter pin, pull the prop and the shear pin is behind that. It should go through the prop shaft and stick out about 1/2 inch on each side to lock the prop to the shaft.