motor poping and not running good. johnson

[matt9923]

I have a 1971 33hp Johnson got another carb, had it going steady but had no one to drive while i adjusted high speed but low speed was good. Today i take it out and it started but was wheezing and popping, i had 2 leaf valve screws out and oil was coming out of them so i plugged (put bolts back in) those thinking it would help. Brought it back out on water and same problem, i have the low speed at 1 1/8 or so and had it able to shift into gear and was driving slow because when i hit over 1/2 throttle it didn't have anything (high speed adjustment). So i figured it fouled because it was running with the slow speed out a alot to get it somewhat steady. Wouldn't start so i pulled plugs and they were wet and black. They have a few hours on them it looks like they have 40+ hours on them.
So why is my engine popping (i heard the popping is from a lean condition) so why is it that know matter how much i unscrew it still pops. How much throttle before it uses the high speed valve. Cause i can get it to idle down low around 1 1/8 turns out so maybe i just need to adjust the high speed?
Im at the point where im looking for a better motor but really don't want to dish out 3000 in less i have to.
Whats a good motor around 40hp with electric trim, alternator i have cable searing now and would probably need hydraulic steering so it would be alot of $ and work. Please help
Matt

 

[Joe Reeves]

Re: motor poping and not running good. johnson

That popping, spitting back, sounds like a mild backfire, is usually due to a fouled or misadjusted carburetor. It may be necessary to clean and rebuild it.
Below are the adjustments for two different carburetors, one that has a fixed high speed jet, the other that has adjustable needle valves for both the high and low idle speeds.

(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.

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(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.

 

[matt9923]

Re: motor poping and not running good. johnson

I have done that, this is the second carb its a 35hp carb. I had it going but i bring it to the water yesterday and it doesn't want to start then when it did it just popped and was ****ty. What would make it do this the carbs clean and in fine condition. I have know clue why it would work and then not work like it adjusted itself somehow even tho the needles haven't moved. My old carb did this ran great the first time an the second time it just **** sucked. SO i got a another one and it was good the first time then it just sucked the next time idk why.
Any other help Matt
Thanks joe i will try it but i still don't understand why this happens. Worked teh first time but this time it just sucked?