68 9.5 johnson not running well after tuneup

[bowtieboy77]

Ran engine before tune up ran well. Changed coils, plugs, points, condensors, and point breaker assy, plug wires new last year, also rebuilt fuel pump. I have lots of fuel to carb and motor will run continuously at higher throttle. I set the points when keyway aligned with each nylon rubbing block. Set the points at .020 Ran engine hard to start and will not run at slow speeds. I tried setting points with throttle grip at start as well as at slow no differance. Spark test shows good spark on both cylinders. Revs good but can't run below start position or it starts to shake and stalls. Out of ideas and two weeks till I need to take it North hunting. Any help is appreciated. The motor is a 68 johnson 9.5 h.p.

 

[joho5]

Re: 68 9.5 johnson not running well after tuneup

did you do any work on the carb? and have you adjusted the low speed needle at all?

 

[bowtieboy77]

Re: 68 9.5 johnson not running well after tuneup

no I havent touched the carb. It ran very nice before I tuned it up. So you would think it should run at the very least the same. I suppose it is possible some dirt got in the carb. Not sure how to set the low speed screw.

 

[Xcusme]

Re: 68 9.5 johnson not running well after tuneup

Here are the carb settings:

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.