Hard starting opposed twin

[adam1961]

I am working on a Johnson OK 15. This motor has been in dry storage for as long as 40 years. When I got it it was stuck from sitting. After soaking for a day, it came free and has now loosened up to the point where it turns over as it should. After cleaning the points, it has good spark. The problem is that it is very hard to start. I have followed the instructions on the tank. Set to choke, center the advance lever and turn out the single needle one extra turn. It seems to have no sign of wanting to fire with the choke on. If I move the throttle to the fast setting, and keep pulling, it will sometimes fire after many pulls (15-20). It seems to be very sensitive to the mixture. Won’t tolerate too lean or too rich. The motor has the Johnson barrel type carb with a single needle valve. I have re-coated the float and it seems to operate as it should. Spark will jump 3/8" gab in open air. Compression is at 70 psi on both sides. The rings may still be a little lazy from sitting for so long.

Any advice on how to make starting this motor easier would be much appreciated. I have limited experience with opposed models.

[jerry-ahrens]

You may want to try depressing the float pin for a bit to cause the carb to momentarily overflow, then try starting. I don’t know if that model calls for this procedure or not but it may help.

[adam1961]

I forgot to mention that I have pushed the float pin down "until fuel runs over" as per the instructions. It seems that it won’t even pop with the choke on after priming it. Seems to get better after many pulls, but then if it doesn’t start it seems to be lees likely to start again.

Is 70 PSI compression low enough to make these motors that hard to start? If I could get it to run for a while, it may loosen u the rings.

[RICHARD A. WHITE]

Are the rings stuck????? that will make it very difficult to start…

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[adam1961]

I would guess that they are stuck. Cylinders seem to have sticky carbon in them in the area where the piston does not travel. Is it work trying to get it running and see if they loosen up, or just pull the cylinders off and given the rings a good cleaning?

[Mumbles]

Hey Adam, I have a few different model Okees and they are fairly easy to work on so for what it’s worth, you might want to remove the cylinders to clean everything up inside. Who knows what kind of oil it burned when it was running so a good cleaning might be all it needs.

One word of caution though, if you remove the rods, make sure to get them back in the way they came out. Left, right, top, bottom. Otherwise the timing will be out 180 degrees! 😮

[ddoyle]

If there is decent and equal compression on both sides I’d be wary of cracking into it too hastily unless you are in a rush to get it on the water. Maybe keep feeding it penetrant/seafoam and turning it over occasionally in hopes that things loosen up further revisit trying to start it in in a couple months?

Just thinking out loud here and no merit to he idea but in a case like this would jury rigging a drill or other electric motor to the flywheel and allowing the engine to "run" for some hours maybe help?

[bh]

If u have ignition, and some compression, and there is fresh fuel mix in the combustion chambers, it will fire. Run,..? So, pull the 2 plugs, squirt some fresh fuel in,
set throttle to wide open, no choke, and pull . Let us know …..

[adam1961]

Well, may be ignition after all. With fuel directly into the cylinders, it won’t even pop. I get a nice consistent spark from both leads to the block when roping it over at even a fairly low speed. I have tried two sets of plugs with no improvement.

What should be tested on this type of magneto beyond a basic spark test?

[stanley]

You haven’t said,but is the exhaust system open?I have had critters build nests in chainsaw mufflers in a short amount of time and it caused problems like you are describing.

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