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cleaning cylinder head & tappets

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Since the block and valves are hard enough, a wire brush works well. For the aluminum piston(which should be at top center) a plastic scraper works well enough. When done, move the piston down a little and wipe carefully to keep the stuff from getting too far down.

The main things to check are if the valves are seating properly or grooved(when lifted) or if the rings/bore look worn or scored. If you shine a bright light down the piston bore sometimes you can see the ring gap where the rings come together. There should be very little gap. It is in the manual for the exact number, but chances are the gap is worn larger making for a lower compression. Does your engine smoke any under load?

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Does not smoke under load. Bought this tractor second hand, so dont know what maintenance has been done, but runs like new. Not bad for 47yrs old. My second landlord has had the valves replaced.

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For my Sovereign I add an ounce of Seafoam per gallon of fuel as a treatment additive to help address the water retention issues common to ethanol (unfortunately no ethanol-free fuel available in my New England region) as well as to help reduce the carbon build-up on the piston and valve surfaces, which was causing some exhaust blow-by from the valves not fully seating.

My cylinder head had more carbon buildup than yours, so I first added a little straight Seafoam down the spark plug hole over a few days to dissolve the carbon, then fired it up. It was a huge smoke dragon until the Seafoam burned off, so start it up outside your garage and be upwind if you do this!

Then I started adding the 1 oz Seafoam / 1 gallon of fuel and the cylinder head has remained carbon free and I no longer have any exhaust blow-by smoke.

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Pretty sure the service manual says to use a hardwood stick or wedge to scrape off the carbon buildup. I used that and a plastic scraper on the last one I had apart.

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