Topic: 1924 2hp BNL Johnson runs rough – Antique Outboard Motor Club,Inc

This topic has 20 replies, 6 voices, and was last updated 1 month ago by The Boat House.

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October 7, 2024 at 5:14 am #291385
Monte NZ
Participant
International Member
Hi All. The motor started on the second pull but I have been unable to get it running nicely. I have flushed out the entire fuel system thoroughly with ammonia and taken the carb appart twice. Compression is good. I’m getting a good blue spark with a good snap.

I have been careful to follow instruction in the handbook

I have opened the needle valve until it starts to choke up and then slowly leaned it out until the motor starts to die and backfire. I have varied the carb leaver from fast to slow to no avail.

I don’t think the motor has been run for possibly 70 years or more. Needless to say, I believe that I have been very thorough and am really puzzled. I have provided a link so you can see and hear it running, plus some before and after shots of the restoration.

https://photos.app.goo.gl/TXANaw9udd4ozDHr7

https://photos.app.goo.gl/5YySdGBd1tGdtwpN7

Thanks in advance for any suggestions.

Monte NZ
October 7, 2024 at 5:24 am #291386
Monte NZ
Participant
International Member
Hi All.
Sorry, I messed up putting the photos in the last message.!

Here they are …..hopefully!

https://photos.app.goo.gl/rBenztNfwpSJQ7W29

Monte NZ
October 7, 2024 at 8:48 am #291389
Buccaneer
Participant
US Member
Hard to tell from thousands of miles away, but it almost sounds
like an ignition problem, i.e., bad condenser or spark jumping
somewhere?

Prepare to be boarded!
October 7, 2024 at 10:17 am #291392
joecb
Participant
US Member
What Bucc said …condensers can be a problem sometimes, even “new” ones can be bad. Do you have a way to do a good test on the capacitor?

Maybe spark plugs?? What is the spark plug gap? Maybe try different plugs

Joe B
October 7, 2024 at 12:16 pm #291396
The Boat House
Participant
Here are some other possibilities if Buck’s & Joe’s suggestions don’t resolve your problem. Baby steps when bending the nozzle. Can be risky. If it breaks your done. Manual says it can be replaced but where would you find one. Tubs
October 8, 2024 at 5:39 am #291414
Monte NZ
Participant
International Member
Thanks Buc, Joecb and Tubs for your replies……..much appreciated!

After reading your suggestions I am suspicious of the condenser. I have replaced it with another, so it will be a bit of trial and error. I have also bought new plugs.

I hope to give it a run tomorrow, but the weather forecast is for rain.

I will certainly keep you informed of progress.

Thanks again.

Monte NZ
October 11, 2024 at 5:05 am #291461
Monte NZ
Participant
International Member
Hi All. After fitting another condenser and two new spark plugs, started the motor today and there was no improvement, so I’m no further ahead unfortunately.

I omitted to tell you that I fitted new HT leads prior to first running of the motor.

Regarding your suggestion Tubs, I’m a bit wary of bending that tube and as you said, once you bust it, you have a real problem!

I would be very grateful anyone has any further suggestions.

Again I have provided a link for you to see the the latest video clip of the motor running.

https://photos.app.goo.gl/askYpJSW99gqkExv8

Thanks again

Monte NZ
October 11, 2024 at 6:46 am #291462
stanley
Participant
US Member - 2 Years
A few more things to check.1-are exhaust manifolds clogged with carbon?The narrow passages on the early A were prone to this problem. 2-Can you feel side play trying to push flywheel side to side?That would indicate worn crank bearing not sealing.You can try upping the oil to gas ratio to 8:1 and see if that helps. 3- I assume crankcase gasket is in place and in good condition.
October 11, 2024 at 8:22 am #291464
Tom
Participant
US Member
Gonna take a long shot here… I worked on a J Johnson that acted like that. Among other things, the piston was in backwards.

T
October 14, 2024 at 4:03 am #291487
Monte NZ
Participant
International Member
Thanks Stanley and Tom for your replies.

Stanley,I checked the exhaust an that seems ok. There isn’t any side play at all and no sign of oil coming up above the bearing,. I haven’t tried upping the oil gas ratio, but I did check the crankcase gaskets and there was sign of any leaks.

Tom, I remember watching a U tube on the Model A and a chap mentioned that his wasn’t running well and he discovered like you, that the pistons were installed upside down in error, so to be on the safe side I had a look. Mine is ok……I took a photo with my snake light to put my mind at rest! One thing I did notice peering down the spark plug hole was that the top of the pistons , on both cylinders, directly under the spark plugs, appeared shiny with very small dents, as if it had been beaten with small hammer. …….I have provided a link for you to have a look.

https://photos.app.goo.gl/xfEhkcYNcjr8647B6

The more I think about it, I feel that it is an electrical problem, so I have ordered a brand new condenser from our local auto store.

I will let you know how I get on.

Thanks again for your suggestions.

Monte NZ
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