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1964-1973 9 1/2 hp kicks in idle

B

buldogbil

Member
Hi,
I have tinkered with 4 of these motors within those years. I noticed that when testing in the tank in idle that they have some sort of a kick, as if it is missing or something. But it seams like maybe the gears are catching alittle. The way it sounds is different than a cylinder missing I think. It is approx every 15 seconds or so. It jerks the motor alittle as if it was interupting the rotation of the crankshaft, like a sudden grab of something. It does not kill the motor but it does sound like if it grabed harder that maybe it would die, but I could be wrong with this hole thing of something grabbing being that I am so new to this. The first thing that came to mind was maybe something is loose alittle with the gears causing them to vibrate to close together and hitting. I have only ran them in the tank not on a boat. They all seemed to run and shift well. I only noticed it in idle in neutral.
PS Are these 9 1/2 hp good motors. They seemed to have made these models pretty close to alike for several years.
 
What you're describing is usually due to a lean running engine. This is normally due to either a fouled carburetor or a carburetor that is set too lean on the adjustable slow speed needle valve.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.


Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S 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 (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.


Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.


Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, 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.


Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
 
A fairly good design but somewhat difficult to work on. They've been around for a long time and I suspect they'll be around for a lot longer.
 
I love 'em. Compact, well engineered and lightweight. Mr. Reeves is right, they can be tricky to work on and note........ mice love to nest in them.
 
i might ad,they do,..have a propensity,to get exhaust,..in the cowling,due to bad seal,..LARGE--and i never liked the shift lever.....but,lower unit and pwrhd,was ,obviously,a good wkhorse.
 
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