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| 88 20 hp johnson, better explained |
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Message |
    
Aaron Dubauskas
Member
Username: aar684
Post Number: 4
Registered: 07-2009
| | Posted on Thursday, July 16, 2009 - 01:32 pm: | 
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Ok all,
I need some help here. This all started a few weeks ago when I purchased a used engine and boat.
No problems with the boat, but of course with the engine. Day 1 with the engine I changed the lower unit oil, greased everything, and put in new plugs. After running it with muffs in my driveway, I assumed everything was ok. Wrong. I took out the boat into clinton harbor and putted around for about an hour and a half with no problems. After about that long, the motor would lag big time when I tried to throttle up. Once throttled up it would either react slowly and increase the rpms or it would bog down totally and stall. I got back to the launch very slowly.
So I got the boat home, took out the plugs. Brand new plugs fouled after an hour and a half of use. SO, Decided to take off the carb and clean it. Just cleaned it, no rebuild kit or anything like that. Then put new plugs in it AGAIN.
Took the engine out again. This time ran for about three hours, with no problems other than an occassional sputter. Got the engine home and took the plugs out again. The weren't AS fouled but they were well on their way. There was also a little bit of unburnt fuel on them. I can only assume that if I run the motor more the same thing will happen again.
Any suggestions? A complete carb kit rebuild maybe? Bad fuel? What could this be? |
Joe Reeves
Senior Member
Username: joereeves
Post Number: 7683
Registered: 02-2001
| | Posted on Thursday, July 16, 2009 - 03:49 pm: |
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What is the compression reading of both cylinders?
With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it?
Hints on carb work follows:
(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
(Carburetor Float Setting)
(J. Reeves)
With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
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 |
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