Back to basics

[willinokc]

1960 Johnson 40 hp, rds-22 engine. Have changed plugs, plug wires, coils, condensers and points. Rebuilt carb and changed lines. Finally got through a overheat prob (separate post), running a test again and trying to trying to adjust idle.

Found out by pulling plug caps to test spark that I'm only running on top cylinder. I suspect this has been one of my probs all along now. I thought possible problems might be a plug wire not seated in the coil right and shorting out. Might also be the vacuum kill switch malfunctioning.

Any other thoughts?

 

[bktheking]

Re: Back to basics

I think as I understood from previous posts on the operation of the switch you can disconnect the vacuum switch to test, it serves as a ground to one of the coils in the event of a runaway/high revving condition. it might be permanently grounded causing your one plug not to fire. If nothing still recheck point gap and wires going into the coils.

 

[Knightgang]

Re: Back to basics

Broken reed valve mabe...
Do you have spark in the cylinder that is not contributing?
Are you getting fuel in the cylinder? Is the plug wet or dry?

There are still several things it could be, but we have to know if it is getting fuel and spark...

 

[willinokc]

Re: Back to basics

Broken reed valve mabe...
Do you have spark in the cylinder that is not contributing?
Are you getting fuel in the cylinder? Is the plug wet or dry?

There are still several things it could be, but we have to know if it is getting fuel and spark...

Plugs wet so getting fuel, no spark though.

 

[F_R]

Re: Back to basics

Plugs wet so getting fuel, no spark though.

The vacuum cut-out switch is connected to the bottom cylinder, so it could possibly be the problem. As a temporary test, just disconnect it and see if yur spark comes back. WARNING, running it without the switch could result in runaway. Better be prepared to deal with it. In the past, I have had to take a hammer to the spark plugs to stop the runaway.

 

[Chinewalker]

Re: Back to basics

Easiest way I've found to deal with runaway is to jam a rag or something into the carb throat to choke it completely out.

 

[Rudi2]

Re: Back to basics

The vacuum cut-out switch is connected to the bottom cylinder, so it could possibly be the problem. As a temporary test, just disconnect it and see if yur spark comes back. WARNING, running it without the switch could result in runaway. Better be prepared to deal with it. In the past, I have had to take a hammer to the spark plugs to stop the runaway.

I KNEW there was reason I had a hammer in my tool kit! LOL!

 

[tx1961whaler]

Re: Back to basics

The vacuum cut-out switch is connected to the bottom cylinder, so it could possibly be the problem. As a temporary test, just disconnect it and see if yur spark comes back. WARNING, running it without the switch could result in runaway. Better be prepared to deal with it. In the past, I have had to take a hammer to the spark plugs to stop the runaway.

Destroying the spark plugs will not normally stop a runaway motor. The motor had turned into a pressure detonated engine at that point. I have pulled the plug wires off of a screaming runaway 2-stroke, and the motor does not skip a beat. The best way to stop it is to choke it out or stuff a rag in the carb throat.

 

[tmcalavy]

Re: Back to basics

Yeah but if you didn't like it to begin with, it'd be fun to snodge the plugs out with a hammer...lot's more fun than the old rag stopper.

 

[tx1961whaler]

Re: Back to basics

Yeah but if you didn't like it to begin with, it'd be fun to snodge the plugs out with a hammer...lot's more fun than the old rag stopper.

...and a lot less messy than throwing a cat in the flywheel!

 

[Knightgang]

Re: Back to basics

...and a lot less messy than throwing a cat in the flywheel!

...but not as much fun!!!

 

[F_R]

Re: Back to basics

...but not as much fun!!!

C'mon guys, the vacuum switch slows it down by killing the spark on one cylinder. Disableing a spark plug, however you do it is the same thing. Choking it with the manual choke usually only results it it running faster than ever. Rag? Maybe, if the carb throat is open and accessable.

Now, thermal runaway where it keeps going even with no spark is a different situation. You might want to duck if that happens.

 

[willinokc]

Re: Back to basics

Found the prob. Total noob or probably would have spotted it right off. The owner before me had the wire from the ignition and the wire to the ground on the same post of the vacuum switch, effectively grounding out that point. '

It was the vacuum switch, just not quite how I thought.

 

[bktheking]

Re: Back to basics

Bet it runs better now ! LOL, gotta love previous owners, dangerous!!!

 

[willinokc]

Re: Back to basics

Yea, running on 2 cylinders did help. Got it out on the lake and encountered some different probs though. Will post a new thread for help if I can't get it figured out. Feel like one step forward, two back w/ this motor.