Small Engines (Lawn Mowers, etc.): Toro snowblower engine oddities continued, fuel mix, spring compressor

Question
Hi John,

This is a followup to a previous discussion, the website won't allow me to post another followup to that thread.
http://www.allexperts.com/user.cgi?m=6&catID=1746&qID=4709280


I pulled the head off to check the valves, and found a fair amount of oily tar in the head.  If you recall, the guy who sold it to me had half-filled the gas tank with 2-stroke mix by accident, and the engine had been run on it for a bit less than an hour before I topped up the tank to dilute it down.
The tar was soft, gooey. and up to 1/16" around the intake valve.  It was crispier,  flakier, thiner, and more like soot around the exhaust valve.  The piston and cylinder head was also covered with a layer, from the edge closest to the valves almost exactly to the halfway point.  Other than the tar, the valves and seats look okay, though I didn't remove then as I don't have a spring compressor.
The spark-plug was completely fouled, almost unrecognizable due to the glob of tar on it.

So, at this point I'm assuming that the engine died when the spark plug reached the fully fouled point.  Perhaps, the compression weakness I detected may have been caused by the tar building up under one or both of the valves.  Not sure about the rough running, but perhaps the carbon was causing knocking, or the carb is partially plugged or something.

I'm hoping that removing as much of the carbon/tar as I can and replacing the sparkplug might restore the engine to a running state.  I'll try to clean the carb as well if I can find a suitable cleaner.
I gently scraped off the tar using an old credit card.  There's still some carbon and gummy residue.  Any suggestions for a technique/product to remove it?

Thanks,
David

Answer
Hi David:

Sorry About you having Problems with the Follow Up System. The Original Owner Must have Been Using a Heavy Oil Mix. Usually Fuel Mix will Not Cause the Goo you Described Unless the Engine has Been Run Several Tanks of Fuel Mix or the Fuel Mix is Mixxed Heavy on the Oil.  Clean the Goo from the Cylinder, Valves and the Head. This May Correct the Problem. The Goo will Also Make the Engine Idle Rough Due to the Intake Valve Not Seating Properly with the Goo Around the Valve Seat. Us Spray Carburetor Cleaner to Remove the Goo from the Components. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John