Got spark and good compression but lower cylinder not working

[KathyD19]

Hi everyone. If you've followed my saga before, I restored a 1956 Johnson Javelin and it ran great. Last summer I did a rewire on it to get the start button and kill switch to the front of the boat instead of the rear. LONG story and many posts, but finally successful. When I took her out for the first lake run, it sounded rough and didn't have the speed it used to have. Doing a barrel test in the driveway, I noticed that if I pulled the top cylinder spark plug wire, the motor died. If I did that with the lower plug, the motor kept running. So obviously, the lower cylinder wasn't functioning. Season ended before I figured it out. New summer, back to work on it. Compression is good, new spark plugs, checked for spark using an in line spark tester (the kind that lights up a bulb) and it worked. Where do I go from here? Thank you in advance for putting up with me.

 

[jbuote]

Hey Kathy!!
Good to see you again!

You say compression is good..
What's the compression numbers?

Also, those inline "Bulb" type testers aren't really any good..
Your local auto parts store should have an adjustable open air spark gap tester... Usually around 8-10 bucks or so...

Set it to 3/8" gap (I think that's what you need anyway) and see if the spark jumps that gap with a nice blue spark, and a crisp "SNAP!"..

Let us know what you find with those..

Still not a pro here.. (LOL!!)
But the pro's will more than likely want to know this info..
They'll also let you know the proper open air gap for that tester if 3/8" isn't it.. haha!!

Hope it helps!

 

[oldboat1]

Best to use an adjustable spark tester (tests intensity) -- believe the setting should be 3/8". Need to see a strong, sharp spark, as jboute suggests.

But it may be a carb adjustment issue. Leaning out the high speed needle may give you better operation (really have to test on the boat). Sometimes the jam nut holding the needle is too loose, and the needle moves with motor vibration.

 

[KathyD19]

Hi jbuote, good to see you're still on here too!!
Off to the auto parts store tomorrow and I'll let you know what happens! Thanks! (Also, can you tell me what the proper setting is for the high speed and low speed needles? They might have gotten bumped and moved at some point...husband throws junk into the boat when it's stored in the garage over the winter.)

 

[lindy46]

If you have good compression, it is either a spark problem, or it could be a faulty cut-out switch. Try bypassing the cut-out switch and see if she runs on both cylinders. The cut-out switch kills spark on the lower cylinder in case of a runaway situation. If it is stuck shut, the lower cylinder points are grounded out and the cylinder doesn't fire.

 

[Chinewalker]

Just a thought - I recently had a '58 35 Johnson 35 in my shop (very similar motor) that wouldn't run on the bottom cylinder, despite solid spark. Turned out the carbon seal on the lower crank shaft had come apart, creating low crankcase compression. Wouldn't draw enough fuel.

 

[KathyD19]

Ok...did the open air spark gap...jumped the gap beautifully. Lots of blue arcing spark. Did a compression test on both cylinders, they came in at 121 psi. So I'm really at a loss. My brother has worked on all kinds of motors in the past so I'm trying to lure him out to my house to look at it. I'll let you know.
Chinewalker, is replacing the carbon seal a huge project or something a non-pro like me could do?

 

[Willyclay]

Also, can you tell me what the proper setting is for the high speed and low speed needles?/QUOTE]

Here are the procedures recommended by forum guru Joe Reeves in his FAQ thread for adjusting your single carburetor with two needle valves:​

----------------------------------------------------------------​

(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.​

-----------------------------------------------------------------------------------------------​

Good luck, Bill​

 

[jbuote]

Ok...did the open air spark gap...jumped the gap beautifully. Lots of blue arcing spark. Did a compression test on both cylinders, they came in at 121 psi. So I'm really at a loss. My brother has worked on all kinds of motors in the past so I'm trying to lure him out to my house to look at it. I'll let you know.
Chinewalker, is replacing the carbon seal a huge project or something a non-pro like me could do?

Ok Good!
Really all you need for the engine to run, is Air, Fuel, Compression and Spark

You have spark, and you have compression...
To finish off the spark side of things, you said in the first post here, you put new spark plugs in.
What did you gap them at? You may already know, but they may not be gapped correctly right out of the box..
In fact, usually not.. .lol

Assuming they are gapped properly, that just leaves air and fuel to verify and then it should run..

I'd think you have air, since the top cylinder is firing..
That leaves fuel..

You said this was happening since the re-wire last year? Did it run good before the re-wire or had it been sitting?

Where I'm going with this, is that yes... I think the next step is to adjust the carbs as outlined by Joe Reeves in the post above by Willy Clay... (He always seems to find what you need huh? lol)

However, if the engine had been sitting a while without being run before the re-wire, and has had this issue since you've tried to "Resurrect" it, then there's a good chance the carbs need to be pulled off and cleaned out with a rebuild kit.. (If you haven't already done that very recently)

With spark (you verified), Compression (you verified), properly gapped plugs, clean carbs, fresh fuel/oil mix in the tank and initial carb settings as described above, it should run on both cylinders.

If it still doesn't run on both, then I'd probably start investigating the seals that Chinewalker was talking about...
That's a bit above my head though.. Haven't had to get that deep into my engines yet... haha!!

I'll continue to answer what I can, but I do think these other folks could probably be of better help than I can be...

Hope it helps!!

 

[KathyD19]

OOOO!!! Big brother came out and fixed it!! I don't know exactly what he did, I was at the front of the boat while he was messing with the motor. He won't tell me either, just smiled. He did say the high speed and low speed needles were all messed up and he adjusted them as much as he could without it being under load. He said I need to get it out on the lake with a friend and run it under load and adjust the needles better. Thank you so much for your input, my wonderful forum friends. Hopefully I'll just be on here to check what OTHER people post and not have any more issues of my own. Laking it tomorrow!!

 

[KathyD19]

**And yes, jbuote, WillyClay always finds exactly the info I need!! He's an awesome friend!
Thank you too for all of your advice. It sure sounds like you've learned a ton yourself as well.

 

[jbuote]

HAHA!! Yes.. Big brother is right about setting needle valves on lake..

Do you think you can convince him to tell you what he did?
Would be interested to know what the solution was (if not just mis-adjusted carbs.. ) lol

 

[KathyD19]

He couldn't get the lower cylinder to work at first either. Then he switched the spark plug wires and said the lower WAS working. Switched them back and it was still working. He used the old fashioned way of checking for spark (holding the spark plug by the boot next to the motor while I started it), after giving me a hard time for being too afraid to do it that way. He didn't expect the motor to jerk when trying to start and he ended up getting a good shock. Served him right for telling me I was being a scaredy cat, LOL. When it was running and he said he really thought the lower cylinder was working now (although I don't know why it suddenly would), he told me to rev the engine but you can't with that motor while it's in neutral, the throttle will only go half way. He tinkered with the carb throttle lever and made it rev manually. Good lord it smoked and stunk so bad...running way too rich (on a plus side, all mosquitoes died). He began looking for a fuel adjustment screw like you'd find with a lawn mower and such but I didn't know what he was hunting for. I asked and he finally told me, so I pointed out the needle valves on the plate. He said they were out a turn to a turn and a half, then brought the bottom one way back down to set and then out only about 1/4. Sounds much better now. Anxious to get it on the lake tomorrow, even though I don't have a helper to drive while I adjust. I just want to see what it's like on water.

 

[jbuote]

Hmmmm... Ok...

Well, I'll defer to the pro's here, but the only concern I'd have with that is if he put the lower (and the top) needle 1/4 turn open from lightly seated, then I might be worried about running it too lean at higher RPM...
That can kill an engine quick... (Too lean, not enough oil = not enough lubrication...)

Is 1/4 turn out from lightly seated too lean?? I don't know...
I might turn it out more in the bucket until it starts to not run again, then turn it in a touch JUST to where it runs...

I'd want to start the adjustments Willyclay sent you with the needles set as rich as they can be, yet still run on both cylinders..

If that makes sense... lol

Maybe I'm wrong here, but that's just my thoughts on it... :noidea:
Maybe somebody will chime in on that to confirm my thoughts, or tell me I'm nuts... haha!! :laugh:

For what it's worth...

 

[KathyD19]

I agree with you that running it rich is better than lean because it gets its oil from the gas input. I will tweak it when on the water and boost the richness.

 

[oldboat1]

If the h.s. air/fuel mix is too lean, the motor will not run -- pretty obvious when adjusting at WOT. This is different (and often confused) with the oil mix ratio -- too lean there (not enough oil) is more subtle, and can damage the engine.

My '57s run best with the h.s. air/fuel mix somewhere between 1/2 and 3/4 open. 24:1 gas to oil ratio.

 

[KathyD19]

Lake test today... had to go without anyone to help me with adjusting while I drove so there wasn't much I could do but I did want to hear it and see how it performed. Here's what I got: started up fine, motor sounds better, less rough. I turned the bottom needle out to the half way point (didn't mess with the top needle at all today) and drove a bit. The engine sounded like it would surge then slow, surge then slow. I hopped back to to motor to check the needle and it had dropped back down to the bottom left again. I think the motor vibrations are working it loose and it's losing it's adjustment. I know I've read of something to do for that, tightening a nut behind that or something, I'll research that. The engine just didn't have the power it used to. Even with the throttle at 3/4, it seemed to be only going at 1/3 to 1/2 the speed AND the throttle didn't respond quickly. If I pushed it forward, the engine may or may not go faster. It seemed to keep losing speed/power the longer I drove it. I didn't have it out long, maybe 20-30 min because I didn't want to do any damage if I have it set improperly/too lean. By the time I pulled back in to the marina, with the throttle fully forward, it was only at about half the normal speed. That's tragic because I really like to drive fast lol. Anyhow...I texted all that to my brother and he said he might be able to go out this weekend with me on the lake and do the adjusting while I drive. He's 61 and he's been working on 2 cycle engines since he was 12. If he can't figure this out I know I sure can't! It sounds like it just needs dialed in and properly adjusted, although I don't understand why the throttle wouldn't be responsive when it used to be. Hmmmm

 

[racerone]

You need 4 things to run that motor.------Spark at the right time.------Compression-------Fuel / air at right ratio.-----And crankcase compression.-----You can have good compression in the cylinder , but BAD / ZERO compression in the crankcase.

 

[KathyD19]

racerone, what do I do to check that and/or fix bad/zero compression in the crankcase? Would it run at all if that were the situation?

 

[racerone]

There are 2 separate crankcases.-----Therefor it can run on just one cylinder !!