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Old 01-20-2009, 09:31 PM   #96
Cowboy OP
Ceteris non Paribus
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Joined: Feb 2007
Location: Elizabeth, Colorado
Oddometer: 3,353
Pics coming soon, Olas! I got a bit sidetracked when I pulled the engine apart, and discovered a big freaking pit in the side of one cylinder wall. Odd, since the bike ran pretty well before I pulled it apart. I really just wanted to replace the seals and gaskets, in order to stop the oil seeps all over the engine. I didn't dare use the cylinder in that condition, as it would likely break a ring or two eventually. Better to fix it right while I have it all apart.

I took the cylinder block to a machine shop to find out how deep they would have to hone the cylinder walls to get the big pit out. They measured the depth of the pit and determined that it would take the bore farther out than the 1mm oversize pistons I could get. I started looking for larger oversize pistons among the race parts suppliers. In the meantime, I found a cylinder block on ebay that was advertised as "good used" for a low enough price to justify the gamble. As a plus, it came with pistons and rings, also "good used", whatever that means.

The used block arrived today, and it appears to be in fine shape. It's dirty, but shows very little internal wear. The pistons are far less worn than the old ones. I'll probably run a flex hone through and call it good, then put it back together with the standard pistons, and fresh standard size rings.

So I'm back on track now. The used cylinder head is soaking in solvent overnight to get the crud off the outside. Then I start the re-assembly.

Progress coming soon!

While I waited for the machine shop, then for the ebay head, I've been turning wrenches on this old CB400 twin. I bought it a few weeks back, based on this photo and a few others like it. The seller told me that it had a seized wrist pin, and that one cylinder had scored the cylinder wall pretty badly. I arrived to look at the bike, and found the engine in boxes. I bought it (cheap) knowing that I had CB400 engine in my parts stash with a good bottom end, and a bad head. The head on this bike looked good, so I popped it onto my old engine, and lifted it into the bike. It runs like a champ now. Got license plates today. My plan is to sell the bike this summer, but I'll enjoy riding it through the spring.

As an added bonus, it came with an Amco rack and a color-matched period top box.

Cowboy screwed with this post 01-20-2009 at 09:44 PM
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