This is a bare-bones description of a quick valve adjustment technique that works very well for me and should work well for you if you have some mechanical sensitivity and your valve adjusters haven't been overtorqued by a ham-fisted mechanic in the past. Valve adjustment is really pretty simple and some people would have you believe that you need to swing incense and chant before you can do the job properly. If you want to savor a wintertime valve-adjustment evening with a pot of coffee and a nice CD, this method will probably leave you spiritually unfilfilled.
In reality, the actual valve clearance isn't quite as important as having consistent clearance among the four intake valves and the four exhaust valves. BMW specifies the gap in increments of .05mm, while the difference between light drag and heavy drag on a feeler gauge is about .01mm or .02mm. Don't sweat the exact amount of feeler-gauge drag, but do make it consistent.
|1. With the bike on the centerstand, remove the valve covers.||Note: some oil will fall out so you will want to place an oil pan underneath.|
|2. Rotate the engine forward to firing TDC for the side you're working on.||
In top gear, rotate the rear wheel to turn the engine. After the intake valves close, you will feel the engine compression. At the end of the compression stroke you will see the OT mark appear in the timing window.
|3. Remove excess slack from the rocker arms if needed.||
Loosen the three T45 bolts and the one head nut holding the lower rocker arm retainer in position. Adjust the position of the retainer so that when the bolts are retightened there is a minimal amount of clearance (I used .03mm, my thinnest gauge) below the rocker arm.
Note: The clearance measured above the rocker arm might not change as you move the retainer - you must measure below the rocker arm. Also, the clearance will change as you retighten the bolts, so expect to have to fuss with it a bit.
Tighten the T45 bolts to 15Nm and the head bolt to 20Nm + 180°.
|4. Slacken off the locknuts and adjusters.|
|5. Put feeler gauges under the rocker arms and lightly snug the adjusters down to hold them in place.||Putting feeler gauges under both of the intakes and both of the exhausts keeps the rockers from twisting and upsetting the accuracy of each adjuster.|
|6. Spin the 3mm wrench between your fingers to bottom the adjusters out against the feeler gauges.|
Repeat this several times and note that the end of the wrench will stop at the same angle every time. This is the final position. Do this for all four adjusters.
|7. Carefully tighten the locknuts, so as not to disturb the position of the adjuster.||You will have to apply some counter-torque to the adjuster as you tighten the locknut. If it moves, you will notice. It's not too hard to figure this part out, but it can't easily be explained.|
|8. Remove the feeeler gauges.||Note that there should be even drag on both ends as you pull it out. If one end holds more tightly than the other, you need to repeat the adjustment on that side.|
|9. Reinstall the valve covers.||
Wipe the gasket and the two metal surfaces clean and dry. Install the outer gasket on the engine and the inner gasket (spark plug hole) on the cover. Tighten the bolts to 8 Nm (lightly bottomed out against the cylinder head).
Other articles on this subject:
IBMWR - longer but still manageable
ADVrider - look for the OVAD document if you are REALLY having problems getting to sleep :)Oilhead valves