compression test

[michael]

What is the proper procedure for a compression test on a 1978 R100/7. I have plenty of time and want to do this right. If there is a special tool needed I will secure one. Thanks for any advice.

[dougie]

You need a compression gauge.
Engine should be at operating temperature (go for a ride).
Carbs should be removed from the heads.
Remove the sparkplugs. My '87 (electronic ignition) requires the plugs be in the plug caps and grounded to the engine.
Put the compression gauge in a cylinder and spin the engine with the starter. A few revolutions should bring it to its highest reading. Note the number, then do the opposite cylinder.

[Deleted User 62]

Hello Michael, what Dougie says is right, but for more information on how not to do it and interpret the results check out Duanes excellent article on the subject: http://w6rec.com/duane/bmw/compression/index.htm

[Major Softie]

You can get away with holding both the slides and the throttle open rather than removing the carbs, but many find it simpler to disconnect them than figuring out a way to hold the slides wide open. Especially since you still need to remove the tubes between the air-filter and the carbs.

If you have Mikunis, Dellortos, or some other non-cv carb, then you can simply hold the throttle open, but it doesn't work with the stock Bings.

[dwerbil]

This looks like another good site for your /7 compression check....
http://www.bmwscotter.com/procedures/co ... esting.htm

[Duane Ausherman]

dwerbil, step #6 is especially important and few seem to know it.

Nobody has mentioned a leak down test.

[Jean]

(If you have plenty of time...go for a ride.)
WHY do you want to DO this thing??