Boxerworks.com

mattcfish wrote:

Tim Shepherd wrote:

mattcfish wrote:
I this case, someone needs to take away his drill.

I would tend to agree:

Drilling the fins was an old mod I've seen on some vintage racers. It was supposed to improve cooling. Any opinions on that?

Here's my take on it: cooling is all about surface area, is the surface area is increased by drilling, then it should work. In this case, however, the holes reduce the amount of metal transferring heat to the outer edge of the fin, so I think not. Also, for a given thickness of fin, the larger the hole the less surface area produced, making me think that a series of smaller holes, say for example the same diameter as the thickness of the fins, would be more effective...

Tim Shepherd wrote:

the quinner wrote:

vanzen@rockerboxer.com wrote:The other side of the "block" contains an "oil condensing chamber"
located to the left of the starter when viewing the engine from the front.
Holes drilled there, without further crank-breather plumbing considerations,
might actually resolve the "stuck breather" scenario that Kurt anticipated.

The only "drain hole" is on the dip-stick side ...

Vanzen's info is true for the 1977 and later blocks...some of the earlier blocks had a drain hole on the right side (rider's right...the non-dipstick side).

Made me look, ya did, and sure enough... one on both sides (R75/5)

Me too.
Type-248 - I have a '80 and '81 - both have two holes.
Looking at some pictures of the bike with the original '79 engine, it did too.

That is what my original statement was based on.

justoneoftheguys wrote:That is what my original statement was based on.

Appreciate the information.

OK – the oldest bike in my garage is a 78 R100/7.
(the 52 in the living room has neither drain holes nor a starter)

Which leaves me curious ... a question, then:
Do these pre-77 and Type-248 engines have an "oil condensing chamber" as the later cases ?

vanzen@rockerboxer.com wrote:Which leaves me curious ... a question, then:
Do these pre-77 and Type-248 engines have an "oil condensing chamber" as the later cases ?

I'm not sure. You are not talking about the crankcase breather, are you?

This is the 1980 block:


click for larger

vanzen@rockerboxer.com wrote:Which leaves me curious ... a question, then:
Do these pre-77 and Type-248 engines have an "oil condensing chamber" as the later cases ?

No. The earliest breathers dumped straight back into the air stream of the right carb tube. At some point, they updated the assembly (breather cover and hose) to exit up then back. Rob's photo looks like the updated parts.

the quinner wrote:

vanzen@rockerboxer.com wrote:Which leaves me curious ... a question, then:
Do these pre-77 and Type-248 engines have an "oil condensing chamber" as the later cases ?

No. The earliest breathers dumped straight back into the air stream of the right carb tube. At some point, they updated the assembly (breather cover and hose) to exit up then back. Rob's photo looks like the updated parts.

The earliest R65's had the breather hose that went into a 'T' to dump into both intake tubes.

vanzen@rockerboxer.com wrote:
Which leaves me curious ... a question, then:
Do these pre-77 and Type-248 engines have an "oil condensing chamber" as the later cases ?

Yes they do. The breather cover is different. This is the best pic I have and only shows cover.



But what is underneath is roughly the same as a 248.

justoneoftheguys wrote: I'm not sure. You are not talking about the crankcase breather, are you? This is the 1980 block:

Thanks again, Rob –
By your photo, I see that there is no condensing chamber as it exists on the later Type-247.

The oil condensing chamber of post-1977 Type-247s
extends the length of the starter housing and precludes a drain hole on that side.
#21 in this pic:

Thanks for the further clarification, vanzen.
So the condensing chamber is companion to the blocks that have the crankcase vent located at the front?

Yes, seems to be the case ...