Good or bad compression and ignition problem diagnosis

[thull]

I have a 1959 10hp Johnson Seahorse (Model QD20). Although it's not currently running (no spark), it's in overall good shape. Someone's gone to the trouble to repaint it two different occassions. I tested the compression and had 60psi in one cylinder and 55psi in the other. Is this decent enough compression to continue putting money and time into it to get it running again? I've read on other posts that "Seafoam" can help raise the compression, so I guess I'll try some of that. Anything else that'll help?

In regards to no spark, I've tested with a spark tester and had nothing. I replaced the plugs, and someone's replaced the coils already (new, shiny plastic and "Made in Germany" on them), so I intend to check the coils for proper positioning and also the points gap. How can I tell if the points and condensers are bad or if they have been replaced? Any other suggestions?

Thanks

 

[lindy46]

Re: Good or bad compression and ignition problem diagnosis

Compression is a bit low, but seafoam soak in the cylinders may help some. If it hasn't run in a long time, it will probably improve once you get it running. Run some Seafoam in the gas also - about 2 ounces per gallon of gas. No spark can be caused by bad coils or improperly positioned coils, old/bad wires, bad points and condensers, improperly set points. If the points show pitting/burning on the surface, replace them. If you have the flywheel off, I'd just go ahead and replace them unless they look new, and also the wires if they look original. Cheap insurance. If the points look newer, file them with a point file or some 600 grit emery paper, and clean them. I usually spray a little carb cleaner on them to clean them.

 

[oldybutagoody]

Re: Good or bad compression and ignition problem diagnosis

Hey Thull, Great old engine. A lot of people will say that compression has to be over a hundred but My experience with these old 2 strokes is that they run at 60. I would definitely say your motor is worth the effort and money. Especially since it already has new coils. Thats $40 bucks staying in your pocket. Compression will go up a bit when its been running a while and you get some oil in the rings. I wouldn't bother with the seafoam until you get it running. Some folks swear by it, some say avoid it. I don't have any experience with it but I think I'd only use it if I saw a lot of carbon on the pistons by inspecting thru the spark holes. Your no spark could be as simple as a wire that has rubbed against the flywheel, grounding out the ignition or bad spark wire connection to the coils, or as you say, coil positioning and points gap. The only way to know is to dive in and have a look at it. I'd say to replace the points and condensers since you have no idea of how old they are and bad condensers will cause your no spark issue. They're cheap so why not fix them while you're in there? I'd replace the water pump impeller and do a carb rebuild too. Give it spark, clean fuel and good cooling and that old motor will run another 53 years.

Here's some links that will make you an expert in no time.

http://www.duckworksmagazine.com/06/columns/max/index6.htm

http://www.duckworksmagazine.com/01/articles/oldoutboards/index.htm

http://www.duckworksmagazine.com/03/r/columns/max/11/index.htm

http://www.youtube.com/watch?v=KT8rk5QWgS0

 

[kfa4303]

Re: Good or bad compression and ignition problem diagnosis

Here's another great link.

http://www.leeroysramblings.com/johnson_QD.htm