1958 10 Hp Johnson seahorse.

[Cresliner2012]

Motor seems too be lacking half the power it's used too. I have taken off Head gasket, one piston is dry as the other is wet with gas. Could it just not be getting spark or gas related. Taking every thing apart and am going too re set the the points and check all connections. Could the engine have over heated on me after the engine seemed too goo down too half power. Insite would be great!

 

[BonairII]

Re: 1958 10 Hp Johnson seahorse.

First.....check compression

Second.....check spark

Third.....clean your carb WELL (a dirty carb will starve cyl(s) of fuel)

 

[1946Zephyr]

Re: 1958 10 Hp Johnson seahorse.

Yep, it sounds like you're running on one cylinder. Probably bad coils.

 

[F_R]

Re: 1958 10 Hp Johnson seahorse.

Yep, it is running on one cylinder (the dry one). The other one is wet because the fuel is not being ignited and burned.

Sorry, have to disagree on the carburetor. The one carburetor feeds both cylinders equally. However it is possible to have a bad reed between the carb and crankcase (rare).

99% of the time, running on one cylinder is spark related. Don't ignore the KISS theory (spark plug???)

No, running on one won't cause overheating. But prior overheating may cause running on one cylinder (no compression.

Finally, ALL 1958 Johnsons have bad coils unless they have already been replaced (have they been?)

 

[Cresliner2012]

Re: 1958 10 Hp Johnson seahorse.

Both coils have been replaced haven't replaced the spark plug wires. Will check the connection between the coils and plug wires. Whats needed too check for compression. everything has been running great. until now. Every now and then the motor will try too pick up too normal speed. kind of a quick kick then back too the slow speed. Taking stuff apart now!

 

[F_R]

Re: 1958 10 Hp Johnson seahorse.

What you describe absolutely suggests one cylinder cutting in and out.

Check those wires for a tiny pin hole where they are clamped to the mag plate. Very common for them to arc through there. Better yet, just replace them.

 

[Cresliner2012]

Re: 1958 10 Hp Johnson seahorse.

One of the points were off rest all points and reset the spark plugs just too make sure. One of the points inside was constantly touching so reset. Think it's good too go now. Testing in the morning on the lake.

 

[1946Zephyr]

Re: 1958 10 Hp Johnson seahorse.

I never replace coils, without at least trimming back the original spark plug leads 3/8" inch from each end. Usually I replace the wires, but occasionally, I'll keep the originals and trim them. I've had several motors that passed through my hands and found that the old wires were attached and not trimmed. Infact, when I replace the coils, I disassemble the whole magplate and clean it thoroughly. Clean the points and everything. They also like to loose contact in the spark plug boots too.