Hard starting opposed twin

[RICHARD A. WHITE]

I had a Ruddertwin with completely plugged exhaust ports…great comp, but would NOT run…hmm, LOL

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

[adam1961]

I haven’t checked the exhaust. It did run for about 5-10 seconds at one point. Heavy smoke. I attributed that to the 10:1 mix that I used and all the OMC engine tuner that went into it to free up the pistons.

Probably worth a look,,,could likely use a cleaning anyway. This motor was only ever run on 30WT oil.

[pappy]

After reading that it will not pop even though you have what looks like good spark try reducing your plug gap down to .025 or even .020. We just did that on an opposed twin a couple weeks ago and it responded pretty well to that change.
If and when you do get it going I would get some genuine OMC Engine Tuner and run it through it. About 1/3 of a can at a time and let it sit overnight with each application. Much more effective than SeaFoam at de-carboning piston rings. It’s the real deal.

[phil-b]

What sort of "basic ignition test"?

The laws of Physics (see http://en.wikipedia.org/wiki/Paschen%27s_law) say the spark needs to be able to jump thru the spark gap times the compression ratio in open air.

So if you have, say 80PSI compression at sea level, that’s 80/14.7 = 5.4:1 compression, and with a 0.020 spark gap, that means you need to jump 0.11" (0.020*5.4) in open air.

BUT if your opposed twin has one coil for both cylinders, you need to double that (with one of the ignition wires grounded).

The "rule of thumb" for post-war engines is to jump 0.25" in open air. If the spark gap is 0.020", that means the spark is good for compression up to 12.5:1 (0.25/0.020), or at sea level, 187.5PSI of compression (14.7PSI * 12.5)!!!

[spike]

I am interested in the responses to your inquiry. I also have an OK-15 that seems to have the same disease as yours does. Compression is the same, good spark and the rings are free. Exhaust is clear, everything looks A- OK but have the same starting problem that you are having. Maybe there is something going on with these OK motors, being only Canadian and all 🙂 Just the same I really want to get mine up and running as I know they are great motors when they are running properly. And also look very cool!

[legendre]

Just asking.. but do these motors have any sort of void, inside the crankcase, where liquid (fuel, oil) might pool up?

2-stroke motors don’t like liquids in the bottom end.. Ultimately, I’m not sure what the issue is.. but I’ve seen plenty of otherwise-fine engines that wouldn’t run due to a build up of liquids in the case.

For kicks, try this – hold the throttle wide-open, and spin the motor until it kicks. When it dies, do it again. If you get it to run a little longer on each go, then keep it up – throttle wide all the time. It might just take off.

[RICHARD A. WHITE]

As old as it is, one might try a magnet recharge… worked flipping wonders on a 1939 Neptune Mastertwin, absolute pain in the arse to start, recharged the magnets and bingo, starts very easy now…. just a thought..

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

[SCOTT MEYER]

quote 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.

I 2nd that 😉

[weedlessdrive]

One last ditch lube the cylinders up good with sea foam or the engine tuner and aft fluid. Put plugs back in and set the crankcase and jugs up 16 to 18 inches from a electric hot plate on low to med heat let the engine warm for a hour or so till it gets good and warm/hot through and through. Set it back up and crank it then. The warmth will usually free up any sludge or gum and make the motor think it was just shut off 40 years ago.
It could free up the rings if it starts and runs once it is warm all way through.
Dale Walksler uses this process on 100 year old Harley’s. I realize outboards are two stroke and tend to dry out more. But it could work and soften everything up.

[adam1961]

It Runs……Kind of
So it seems to be flooding. I pulled the exhaust. There was a little carbon, but nothing major. No nests, critter or other foreign matter. Took a peek in the exhaust ports and pistons look brand new. Rings are free.

After putting it all back together, on the first pull (with choke and carb primed) it popped and then nothing. I tried all sorts of settings, but nothing worked. Finally, I shut the fuel valve and walked away. After a few minutes I went back at it. I had forgotten to open the fuel valve. She fired and ran for a bit, then leaned out a died. I opened the fuel valve fully and it flooded again. I shut the fuel valve and pulled till she fired. I then opened the valve while it was running and it seemed like it would stay running long enough to adjust the carb.

The carburetor is clean inside. The needle and seat look good with no evident wear or corrosion. I re-coated the float and it rises as soon as the fuel hits the bowl and continues to float. The retainer clip for the float is in the correct groove on the needle. I don’t see anything obvious in the carb, but it overflow through the air tube if the fuel is left on. I had the needle turned out between 1/2 and 1 full turn.

Any advice on getting the flooding resolved would be great. It seems to start great as long as the carb is not running over with fuel.

[Author]

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