Forum bmwbike.com

Further to previous messages concerning unusual engine noises ( R26 Motorgeraeusche):
After reboring the cylinder, the new piston, new valves, etc. have been refitted and the whole bike was re-assembled. It started on second try.
Nice improvement of performance. I wonder why, but even previous problems down-shifting gear disappeared completely.

Only problem is, that this rattling noise is still there. I'm rather sure now that it is the rocker arms which make a sound like my grandma's pedal driven sewing machine or dried peas poured into an empty tin can. The rocker arm on the exhaust valve has a clearance of 0.65 mm to the sides, the other one has 0.25 mm. According to the manual it should only be a fraction of that. What can I do about it? Would a new or thicker washer help. How to dismantle the whole rocker set. It seemed to be shrinked on. I couldn't find any relevant parts in your catalogue.

Hi Thorsten
Side play of rocker arms according to the BMW manual is .02 - .06mm. This can be tested with a feeler gauge. If it is too much, loosen all 4 cylinder bolts, tap the rocker shaft holders with a hammer and soft metal block inwards until the required play has been obtained and then re-torque all 4 bolts as described in the manual.

The rocker assembly are lightly pressed together and can be easily pressed apart or together in a vice or even knocking with a hammer and the suitable drives so as not to damage or butcher the parts.

Hope that info helps you.

Best regards,

Mark
Mark Huggett GmbH

Hi Mark,
Thanks a lot for your advice regarding rocker arm adjustment. Unfortunately I wasn't able to read your message on time. ' went out for a short test drive the night before. Bike started on first try this time. Just when I turned around homewards the engine missfired, stopped and refused to restart. 'lost four pounds pushing the bike back home. 'seems I live in the only uphill area in Manila.
Dismantling revealed that the eye for the valve adjustment screw was sheared off from the exhaust valve rocker arm.

Can anybody tell me where to get a new rocker arm?

Thanks n regards

Thorsten