2hp Johnnyrude electrical problem

[wedgie]

Out of three motors I cobbled together one. It wants to run, but has electrical gremlins. The ground strap from the bottom of the mag plate and the exhaust cover is good. All the ignition is new except the condenser. I have swapped in 3 used ones hoping at least one of them would be good. 😆

When running it in low light, you can see arcing between the throttle advance lever and the recoil housing. That cant be right can it. ❓

[Mumbles]

Did you try replacing the ground wire with a new one? Even though it may pass an ohm reading test, it may be broken under the insulation and wont let the high voltage from the secondary windings thru. It may be connected by only one strand.

[wedgie]

Yup. replaced the wire even though the original tested OK when wiggling it around.

[Mumbles]

Try checking the mag plate to block for continuity?

[Mumbles]

I’m not sure if this will help but here’s another two horse motor the same as yours I saw earlier today.

The owner had mag or flywheel problems and put a flywheel from a DS 38 on it. It runs great and now he wants to mount an old horseshoe tank on it!

[frankr]

Wedgie, that is exactly the sort of thing that ground wire is there for. For the life of me, I don’t see how it can be present and not doing it’s job. I suggest doing what mumbles said, check the continuity.

[jerry-ahrens]

Does that engine have the "white” colored coil? If so, the coil may be cracked on the bottom where its not visible. I’m working on one of those right now myself. You almost have to do a coil power test on the Stevens oor Mercotronic machine to make sure the coil is good.

[fleetwin]

Yeah, if it is arcing between the throttle control and the frame, then the mag plate is not properly grounded. Are you getting shocked when you touch the throttle control?
I would definitely use an ohm meter and check the mag plate for ground before going further.
Calibrate the ohm meter to the low scale, connect one lead to a good clean ground on the block, not the place on the exhaust manifold where the ground lead is currently connected. Now connect the other lead to a good clean spot on the mag plate, not the place where the ground strap is connected.
The meter should read less than one ohm, as close to zero as your meter will allow when calibrated properly (two ohm meter leads connected together.
A reading above one ohm (or more than a few 10ths higher than your calibrated reading with leads touched together), means the mag plate is poorly grounded. These ground leads are a trouble spot, and often overlooked when these engines are used in salt water. The connection on the exhaust manifold gets rusted, and there should be a star washer between the ground strap and the exhaust manifold. The manifold cover is not the greatest ground to begin with either, so be sure the bolt threads and shank are cleaned up well. The little mounting screw under the mag plate is usually rusted as well, oftentimes breaks off when you try to remove it.
Keep in mind that the lead might be damaged, having only a few strands actually conducting the ground path, the ohm meter would fool you in this case.
I guess I should have started with the simplest troubleshooting technique first! Connect a decent jumper lead from a good engine ground to a clean ground on the mag plate while the engine is arcing or missing. If the miss clears up/arcing stops with the auxiliary lead connected, you have a ground strap problem.

[chris-p]

^^^^ Quickest and easiest test I would think to start with! If the jumper works, you know what to do.

If not, I have seen damage on the bottom of the coil as well as mentioned above. Looked brand new on the mag plage, so hard to notice.

[wedgie]

I tried the jumper already and still it seems like an electrical problem. The coil and points are brand new, and just to rule out a bad new coil I swapped another new coil in. There are two standoff bolts that secure the tank ring to the front of the carburetor. I had been testing the motor without them in place, so I put them back in and still no difference

I can get it started, and if I tickle the choke just right it will take off at high rpms .When the throttle is moved back to prevent over revving and throwing too much water out of the barrel, the motor dies like it abruptly looses spark.

Could what seems to be an electrical problem actually be carb related?
have checked the carb multiple times and even thrown a kit in just to be sure.Reed plate looks fine too. Mumbles suggested there could be an air leak around the throttle shaft from wear, so I put some heavy oil on it with no difference. It’s weird ’cause at one time I had this motor idling pretty nice, and the compression is around 110 lbs.

Thanks for all the suggestions.

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