The compression of your engine at 130 psi on both cylinders is outstanding.
The spark plugs should be Champion L78V plugs, gaped at either .030 (long life) or .040 (strong spark)
With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP... Does it?
NOTE-1: Once the carburetor is set properly, it does not normally need to be reset in order to restart the engine. If it does, then something is vastly wrong within the carburetor (flooding/starving) or the fuel pump diaphragm is cracked and leaking fuel into the crankcase.
NOTE-2: A contradiction to the above is that between a very hot day and a very cold day, the slow speed adjustable needle valve may need to be moved ever so slightly (1/8 turn) one way or the other to obtain a smooth idle.
Make absolutely sure that the carburetor is thoroughly clean. Do not depend on solvent and sir pressure alone to to clean those passageways... use carefully a piece of single strand steel wire to do that job, then follow up with the solvent and air pressure.
The high speed jet that is screwed vertically up into the upper body of that 8hp model should be marked with the imprinted number of "36" (.036 ID). Fuel must flow through this jet before the fuel can gain access to any other passageway.
When all of the above is as it should be............... Adjust the carburetor as follows.
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(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.
Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
Let us know what you find.
