Gentlemen I have started on a 1967 CL77 matching number bike with 13000 documented miles on the motor. Upon tear down due to a frozen lower end (which has been freed), I have made the following discoveries. The bore is stock. There is a chip of metal missing from the left piston but I cannot find any corresponding damage to the cylinder wall. The walls really look good, no deep scratches or gouges. In areas you can still see honing marks. A new set of standard rings when checked in the cylinders are well under end gap specs. Piston skirts are between .003-.004 on each wall. The cylinder head is in great shape, no rust, the valves look good, and it passes a leak down test with no problem. I am looking at the following options:
A. Re-hone the walls, look for one or two good standard pistons, re-ring. (Of course new cam chain, seals, gaskets, and valve lapping are included in all of the options being considered.)
B. Bore 25 or 50 over and look for stock pistons and rings which are more accessible and insure a good everything is covered rebuild.
3. Consider the Wisco piston kit which comes with new pins, rings, clips, after a bore of 50 over. I have talked to the vendor offering the kit and the he states the pistons are of much better quality than stock and afford greater compression.
I am attaching a few shots and I apologize for the photography. As you can see from the condition of the bike, I have a long way to go, but it is going to be a long winter. I have a quote from a good powder coater, so that is step one. Thanks for any input.
What would you do?What would you do?
Marzini. The chip (actually chips), there are two, one large and a smaller one. Both are located between the ring grooves making the piston landfill bound. I still don't understand how this did not damage the cylinder walls. All of the rings were intact when the cylinder was removed, must have been the saving grace. Here's another option Britman. Hone the cylinders, use new standard piston, and .25 rings. File the ends of the rings until you achieve optimal end gap. I have done this on a couple small bore motors with excellent resuts. The wiseco pistons are indeed a thing of beauty. I have done three 305 engines with them , and am very pleased with the results. See my thread under Restoration projects, CB77 engine rebuild for some pics of wisecos next to stockers.
davomoto Dave, I really leaning toward the Wiseco kit. Those pistons are really a thing of beauty and good price for the entire set. I am going to make the call in the next couple of days since I have to go out of state to get the punch work done. Most of the local shops in my area have gone belly up or won't do a bore that small. This 67 is going to be a keeper for me, it is the same year I graduated from High School and it was the one bike I really wanted back then. I also need to add some international flavor to all of that British in my garage. weisco pistonsbritman, the weisco's are a good investment. I've used them on my 305's and they are fabulous! I bought mine off ebay, but I'm sure you can get them cheaper somewhere else. I will tell you I have built 6 305's in the last year and I have used the d&k gasket kits off ebay, well out of the 6, I've ran 4 of the engines, to which every one of them have leaked oil at the headgasket. The heads and cylinders have been surfaced to ensure flatness, so I'm fairly certain its faulty gaskets. I talked to a friend of mine and he had the same problem with his, so he switched to a genuine honda headgasket and that took care of it. So in short, find a nos headgasket and o rings if you can. I have to pull 5 out of the 6 motors of mine back down and replace the headgaskets. Hope this helps! nutt
Wiseco pistonsI happen to have some CBX piston sets that I have been toying with the idea of boring my cylinders and using for a "big Bore Kit". From first examination the piston pin height looks to be the same, skirts are somewhat shorter (no big deal as better than longer) and maybe slightly larger bore size. CBX is 64.5 mm I believe. Should "warm up" my CL some.
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