Dead 123

Sun May 23, 2010 9:50 pm

Tried to start the 123 for the first time in over a year. No luck. I have spark and the plug is wet. It wouldn't even pop on a shot of ether. Coil, points, and condenser are just a little over two years old. Any suggestions? I'm thinking stuck valve, but am not sure how that would play in with the ACR.

matt

Re: Dead 123

Sun May 23, 2010 10:22 pm

The ACR is only on the exhaust valve, but it wouldn't come into play if either valve was stuck open.

Re: Dead 123

Mon May 24, 2010 6:42 am

Where did you test for the spark :?:

Re: Dead 123

Mon May 24, 2010 10:05 am

Finger in the spark plug hole. You will feel some compression even with the automatic compression release.

Wet spark plug would indicate that you have suction and compression.

My next check would be the points, gap and condition. Then spark quality. Then the carburetor.

Re: Dead 123

Mon May 24, 2010 10:06 pm

Cub-Bud wrote:Where did you test for the spark :?:


Removed the plug and grounded it. Spun the engine and got spark.

Re: Dead 123

Mon May 24, 2010 10:12 pm

Eugene wrote:Finger in the spark plug hole. You will feel some compression even with the automatic compression release.


I'll start with compression. I'll borrow a compression tester and report back.

matt

Re: Dead 123

Tue May 25, 2010 8:13 am

A compression guage or tester is not going to give a correct reading if the ACR is working and or the valve(s) are stuck. If the valve(s) are not stuck and the ACR is working, it will open the exhaust valve slightly on the compression stroke and the tester will give a false reading. Like Eugene said, put a finger over the plug hole and spin the engine over and see if you can feel any compression buildup. Since K series Kohlers are known to have problems with blown head gaskets, I would remove the head, then you can determine if either valve is stuck (probably), clean out any carbon buildup, and check the head to be sure it is true and flat. Install a new head gasket, torque the bolts, run it till it gets up to operating tempature, let it cool and retorque the head bolts.

Re: Dead 123

Tue May 25, 2010 6:50 pm

Do you have fresh gas or old gas? The old gas could be your problem. I notice the gas we have now goes bad very fast when were not adding seafoam to it.

Re: Dead 123

Mon May 31, 2010 10:37 pm

Used the "thumb" compression tester today and felt pressure and suction. A real compression tester showed 30 psi.

Took a close look at the spark with the plug grounded to the engine and it was blue to blue-yellow with a nice little snap.

There was some older gas in the tank that had MMO in it. I had added some fresh gas prior to trying to start.

Again, it wouldn't pop on a shot of ether. Should I try a splash of gas directly in the spark plus hole?

matt

Re: Dead 123

Tue Jun 01, 2010 6:14 am

In your earlier post, you said that the spark plug was wet, did you clean it or replace it with another one? Since you have compression and the engine still won't fire on ether, the plug is not firing. Try a fresh plug or one from a running engine and see what happens.

Re: Dead 123

Wed Jun 02, 2010 10:45 pm

Gary -

I have not tried another plug. I grounded the original plug to the engine and it sparked nicely as I rolled the engine. Would there be a reason that it would not spark when installed if it sparked when grounded?

matt

Gary Dotson wrote:In your earlier post, you said that the spark plug was wet, did you clean it or replace it with another one? Since you have compression and the engine still won't fire on ether, the plug is not firing. Try a fresh plug or one from a running engine and see what happens.

Re: Dead 123

Thu Jun 03, 2010 4:13 am

Yes, it requires much more spark voltage to jump the plug gap under pressure, so it may be finding another path to ground. A wet plug will easily short to ground.