Boxerworks.com

Hi all, I've come to Boxerworks looking for a bit of information.

I've recently picked up a 74' R90S in bits and am in the process of putting it back together. It's a slow process as every part has to be located in the boxes and then checked to make sure its good. There are a heap of spares with the bike and it's often hard to figure out which part is the original. This process is made harder still by the original owner (who I've never met or spoken too) having brought or sourced a heap of aftermarket or performance parts and then chucking them in with the standard bits.

At the moment I'm trying to figure out which of the two available cams to use. The best I can do is measure lift and take pictures.

Here's the two side by side



Here's the lift numbers

The cam marked 921 measured 6.75mm lift on all four lobes, x1.39 = 9.3825mm or 0.3693"

The cam marked 630 measured 7.64 lift or near enough on all the lobes, x1.39 = 10.6196mm or 0.4180"

If anyone's got any idea what either of these two are I'd love to know.

Cheers

Sam

Welcome to the forum Sam.

It looks like you're going to need a lot of help/support/wise ass comments. And finally we have somebody to admire our vast reservoirs of airhead lore.

This is a match made in heaven!

Uh, or maybe not. For many of us our greatest expertise is in the construction of clever remarks about posts that catch our eye.


Ken

How did you measure the lift?

This way: http://www.youtube.com/watch?v=D0WaGnhklso

Or this: http://www.youtube.com/watch?v=tULdhaOyu8A

The second takes a bit more set up but gives a measurement that will match factory specs.

Welcome to the nut house.

Checked them in the lathe with a dial indicator on the bed.

All comments are appreciated, even wise ass ones.

SamH wrote:All comments are appreciated, even wise ass ones.

Careful Sam, that's like a red rag to a bull. There sure are some wise asses here.
If I can, I'll try and point out the worst offenders to you.

SamH wrote:
All comments are appreciated, even wise ass ones.

I'd use the one that wasn't all rusty.

Major Softie wrote:

SamH wrote:
All comments are appreciated, even wise ass ones.

I'd use the one that wasn't all rusty.

There ya go Sam, there's trouble maker No.1
We do try to keep him in line. It can be difficult.

The rusty one's been cleaned, it's all shiny now. It's also the one with the higher lift.

I just noticed, looking closer at the photos, that the cams do not appear to be the same length. Is this just a trick of perspective because the bearing carrier is holding one up higher? If not, I think I'd use the one that was the correct length.

Edit: nevermind. In researching, I see you've gotten an answer on advrider. Interesting that I can't find anything else on the web about the numbers printed on your cams.

Quote:

The cam marked 921 measured 6.75mm lift on all four lobes, x1.39 = 9.3825mm or 0.3693"

The cam marked 630 measured 7.64 lift or near enough on all the lobes, x1.39 = 10.6196mm or 0.4180"


BMW specs.
308 has a lift of 9.4mm
336 has a lift of 10.68mm
284 has a lift of 8.62mm

Lucky you. #630 has the lift of a 336. An early one with a key drive on the OP is a rare thing......#921 is a 308.