View Single Post
Old 09-01-2013, 07:24 AM   #60
cameron110 OP
Gnarly Adventurer
cameron110's Avatar
Joined: Jan 2005
Location: C-ville, VA
Oddometer: 477
Originally Posted by disston View Post
Agreed Lornce, most will choose this option for the same reasons. The OP's block was already off the bike and already stripped I think. And then he just happened to run into somebody who would do either. Not going to happen that way for too many others I think.
I had a pile of parts type bike with no particular plan other than have fun, learn more about indepth work on airheads and create a town/fire road ripper. When I pulled the heads the bore on one side was pretty rough from sitting with water in it. We had a set of Nik 800cc jugs and pistons lying about, new rings for that set are much cheaper than new slugs and rings if I were go up one size on the origional jugs.

With this project as much about learning more about airheads as anything else I was happy to strip the block and once I found Mr Colliers shop my course was set.

Originally Posted by disston View Post
Here's one problem mentioned by Mr Bum but it's not the one I'm looking for;

One last bit of information about the cylinders needs to be made here. In the later 1980's, BMW added a sort of "step" machined into the cylinder spigots, and a similar matching step was in the crankcase opening. If you try to fit late cylinders to an early bike, you MUST machine-off the step.
That step he is referring to is the reason I had to go back to Mr Collier to get the O-ring step added. I contemplated having him just put a bigger chamfer on the corner to clear the "step" which would have worked, but I figure if it's going in the mill I may as well be able to run o-rings. The extra step in the portal can be seen in this photo, I'll try to remember to get a pic of the offending step on the spigot when I'm back in the shop on Monday or Tuesday.

Originally Posted by disston View Post
I believe the difference is in the counter weights. Some counter weights were larger, maybe they are heavier. Yes the stroke is all the same. But the counter weights also interfere with actually getting the cranks in and out of the blocks.
I seem to rememeber having heard or read about people having problems with the interference you are talking about in some cases. I havn't test fit the cylinders since getting the crank back in, I'll let you all know if I end up with contact. We also have a variety of cranks and jugs lying around so I'll try to rememeber to do some comparison measurements and see if I come up with anything interesting.
Resurrection of a: Mongrel /5
Ride Report: West Africa How to: DRZ400e tail bag using Wolfman Lg Expd Tank Bag
Good behavior is the last refuge of mediocrity.

cameron110 screwed with this post 09-01-2013 at 07:34 AM
cameron110 is offline   Reply With Quote