RPM drops when clutch pulled

[dellatorre6708]

Got a R60/2 basket and rebuilt it. Runs great except... when I pull the clutch the RPM drops. Any thoughts?
Thanks. Frank.
NYC.

[schrader7032]

Not sure but I wonder if you can see the flywheel move when pulling on the clutch lever. With the engine not started, pull the plug for the timing hole. Actuate the clutch lever and watch the position of the flywheel.

[scottiesharpe]

When rebuilding the engine, did you measure the fore/aft movement of the front crank bearing inside the bearing carrier?

It should be measured using feeler gauges.

BMW Provides several versions of the front carrier retaining plate with differing depths of the lip (retainer plate with the little oil tube sticking out of it, part number 11 11 0 002 174).

The fore aft movement of the bearing inside this plate should be minimized (0.003" max) by using a different size 174 plate, or by shimming the bearing. If the clearance is excessive, the crankshaft can move fore/aft when the clutch rod forces against the clutch main spring, causing the results you are experiencing, also the front slinger can rub against the back side of the carrier.

You can actually measure this item and service this item with the motor still mounted in the bike, but it's a pain.

[dellatorre6708]

Thanks for the replies. I'll use all of your info to hopefully remedy my concern.
Frank. NYC.