- This topic has 25 replies, 11 voices, and was last updated 7 years, 7 months ago by
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They needed that heavy oil to seal the rotary valve. Carbon buildup in the driveshaft housing was always a problem. Later models had sealing rings on the valve that are also used on later V-4, 6 & 8 models. The racing model had roller bearings on the connecting rod big ends and crankshaft mains. Also high compression two ring forged pistons and open exhaust. Several antique "A" racers made high compression pistons the convert the Army-Navy surplus Johnson 10 horse water pump (which had the roller bearings) into a class"A" racer. . . 😀
I think I have the center section cleaned out. Anybody want a start to make a diamond? Just need some pressure and a few thousand years and wha-la! Seriously I think Johnson had a engineering mistake when they built this center section. The center section on this KD15 is a aluminum casting with three tubes cast inside. Up water, down water and two exhaust. Must of been a bugger to cast. The voids are rough and there are casting slag that catches debris. Plugging is inevitable! Easy fix= exhaust cutout!
She’s on hold for a while, yard work!
Thanks to anyone that contributed to this tread!dale
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Today’s 2 cycle oil is so much
better than that of the past. Motors
exhaust could become so blocked
with carbon that they wouldn’t run
wide open. Only a small percent of
today’s oil burns. That’s why the
smoke is gone. That along with the
detergent they have today its put
an end to this PIA.
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