Johnson 4HP 1971

I have a 1971 4HP Johnson, It is hard to start, it has 2 different ideal setting, High speed low speed. I think I have it figured out where they need to be to start also the starter handle ( throttle). After several pulls it will start and run fine but when I try to ideal it down I need to change setting. After I get it to ideal ok. If I shut it down I can not start it again. I has plenty of water to cool. I am getting old and need it to start on one or two pulls. Thanks Sailor George

Re: Johnson 4HP 1971

(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.

Re: Johnson 4HP 1971

Answred

Re: Johnson 4HP 1971

Thank you for the quick response. I will give it a try tomorrow. When I start to adhust should I start at where it says lean? I assume that would be closed.
Again thanks
Sailor George

Re: Johnson 4HP 1971

Start as I said... gently turn those adjustable needle valves in first, seating them, then.......

Re: Johnson 4HP 1971

Great advise above but just to be clear you will need to pull the plastic knobs off to allow for free movement. Once your happy with your settings put them back on at the mid point. Best of luck. Rick.

Re: Johnson 4HP 1971

Read the last paragraph in Joe's instructions. Once set, there is no reason to keep monkeying around with them.

Furthermore, the initial settings are to get it running. Yours already runs, so that step really isn't necessary. Simply set them at the sweet spot at full throttle and idle, then forget they are there.

I hope you aren't trying to adjust it while running in a bucket. It needs to be on a boat, on the lake to get it right.

One or two pulls is nice, and probably possible, but not always realistic either. And that 4hp starter design takes quite a yank to crank it over fast enough. Not to mention the rather imprecise throttle lever. Hey, I'm getting old too. Bummer, isn't it?