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dentwizz

12 hp questions

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dentwizz
I just had my 23D disintegrate a piston, so a search of ebay revealed a 12hp 300421 engine from a B112. I brought it home and reworked it with a magnetron coil and air unit from the 23D. Some new throttle shaft bushings installed, some new paint and it runs. It also took a load of work to fit into the shorter nose of the early LL grille. The problem is the run is not the smoothest. There is no surging and it seems to still have good torque but it skips every now and then. I checked plug gap(tested .020-.045) and the wider range ran smoother, which seemed to tell me that the flywheel key was dented or sheared. I took it back out of the chassis and attempted to take the flywheel off to look but it was immovable. I used a briggs style puller, a 3-jaw large puller and heat to no avail. Is there a method for taking these off? Usually they don't resist the pullers that bad. In response, I loosened the coil mount interface bolts and slid it forward to try to make up for percived dented key. It helped mostly but still seems to skip some. Could that be a valve train thing? It runs good at the mid range but breaks up toward the top end. Magnetism of the flywheel was similar to the reliable magnetron grade flywheel in the 23D. What are the tappet clearances on this model?

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dentwizz
Update: Today I had to tear into it to find an oil leak, so I figured I would try everything again and see what a new perspective might get(Plus I had run it around an hour so some things were warmer). The Crankcase breather was shot, replaced from spares. Valves were at zero clearance, had to gap them a bit. The flywheel apparently had been soaking since the attempt to PB Blaster it last time, because I hit it with the 3 jaw puller and impact gun for about 30 sec continuous and it came off. The key was undamaged and the flywheel was in time, but the skipping and popping went away when I swapped the flywheel from the Magnetron converted 23D engine(the offline engine). Now it runs like a watch and doesn't smoke. It will even run the deck at idle without hesitation. What is really impressive to me is that when I mowed one of my customer yards today the fuel consumption was between 1/2 and 2/3 of what the 9hp engine would use. Good for the biz bottom line indeed:D

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