1983 Johnson 2hp J2CTD-adjustment Q's

smallblock

Seaman
Joined
Sep 5, 2009
Messages
57
Im looking for where I should reset the low and high speed adjustment after cleaning/rebuilding carb. In the past on other carbs I have seated it, then turned out a turn and a half. Does this sound about right? Also when I got this motor it had a J8C for a plug in it, is this the correct plug? Seems like a Jc4 would be more appropriate but I just dont and depending on where you look you get different answers. Thanks for all the help....Also is their any way to make your own packing washers? I hate to buy a whole kit just for these washers...
 

1946Zephyr

Vice Admiral
Joined
Oct 21, 2008
Messages
5,556
Re: 1983 Johnson 2hp J2CTD-adjustment Q's

Yes, one and a half turns out is a good starting point for the carb. A J6C spark plug is about right for that motor. The J8C spark plug you have will work fine though.:cool:
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 1983 Johnson 2hp J2CTD-adjustment Q's

Packing washers can be bought separately (307583)

(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.
 

smallblock

Seaman
Joined
Sep 5, 2009
Messages
57
Re: 1983 Johnson 2hp J2CTD-adjustment Q's

Thanks for the great detailed instructions. This motor is in great shape but was neglected and was filthy...Also there was a cork gasket that sets on the high speed needle. It is garbage. Is this gasket absolutely necesary? Can I make a new one out of cork gasket material? What is the purpose of this gasket, never seen one before? Thank you!
 
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