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Flat Top 

Two-Stroke Software Review

Part 1

Flat Top A few pictures here show the barrel lapping procedure. At one time or another I lapped every surface that I could while putting this engine together.
The granite slab is outfitted with 600 grit wet-dry paper and WD-40 as a lubricant. I carefully and slowly grind in the barrel.	After cleaning up the surface to remove any machine marks I proceed to make it flatter using glass this time.
Glass Flat Glass is pretty flat. A piece of 1/4" glass placed atop a clean tool room grade granite slab and taped in place will make a wonderful surface to match to. When glass is used with an abrasive both parts will have their surfaces affected. That is to say, in this case the barrel AND the glass will show wear. After some time it will be necessary to change the glass for a new flat piece. The key here is to not be in a rush and be willing to let the abrasive do the work. There's little to do except keep the pieces moving against each other in a repetitive motion. Tilting or rocking the parts is prohibited! On a piece like this it's best to hold it as low to the glass (the lowest cooling fin) as possible. Some pieces are much more difficult to keep in place, while still others only allow a back and forth motion (reed cages). Every engine part is different with regard to this - what matters is that the parts come out as flat as possible.
When using glass there's no abrasive medium without adding one - I use Clover "fine" grinding compound to help me cut this surface. First I spread it out with my finder, add a little light oil (WD's OK) and...	... carefully place the barrel on top of the stack. This is the starting point for lapping operations. When a part has to be as flat as possible, lapping will achieve it. Even if the barrel didn't need it - I wanted it to show how it's done.
After a few minutes of slowly rotating the barrel using a pattern of small circles, I checked it. I could see that the gasket surface had been completely cut - this is evidenced by noticing a surface "grayness." The bright shine of the wet-dry paper has been dulled by the lapping compound.	The glass is hard to see but in the center is where the barrel was just lifted from. The surface adhesion created by doing this is quite significant. It is usually best to apply upward pressure to the part and wait while the suction releases. Sometimes it can take a couple of minutes.

Part 1 - Part 2 - Part 3 - Part 4 - Part 5 - Part 6 - Part 7 - Part 8 - Part 9 - Part 10 - Part 11 - Part 12 - Part 13 - Part 14

Two-Stroke Software Review

Part 1