No Clearance On 1st Valve Check

Third post today so I apologize for that. Checking valve clearances on this '84 R100RT with 35K on it. Bike ran fairly decent last season even with torn diaphragms in both carbs. I rebuilt both carbs and have moved on to checking valve clearances. Per 'bums method, I rotate rear wheel until left side intake valve starts to move outward. Keep bumping wheel. See a "Z" mark. Bump it a little more and see the "OT" mark. Unless I missed something, this is where I should be but neither the exhaust valve or intake valve have any play in them. Am I missing something here? The pushrods do turn freely yet there seems to be no valve clearance. Where do I go from here?

Per 'bum's site, one cylinder will be tight and one will be "loose" at the OT. The one that's "loose" is at the proper position for valve adjustment. After setting that one, rotate the rear tire until the OT shows again and adjust the other side.

Sounds like you did everything right. Is this the first time you've set the clearances? Bike new to you? If so, then set to the proper clearances and make note of the miles. Check it again in say 3-5000 miles. If everything is OK, they should still be where you set them. The '84 model is at the end of the era that got the bad metallurgy for the valve seats. BMW fixed the problem with new seats in 1985. If your clearances continue to close up, then you'll need to replace the valves, seats, and guides sooner rather than later.

Manfred said:

Per 'bum's site, one cylinder will be tight and one will be "loose" at the OT. The one that's "loose" is at the proper position for valve adjustment. After setting that one, rotate the rear tire until the OT shows again and adjust the other side.

Click to expand...

Unfortunately Manfred there is no play on either side with the exception of a little visible movement on the left intake. Should I just back off the adjusters and start from scratch?

20774 said:

Sounds like you did everything right. Is this the first time you've set the clearances? Bike new to you? If so, then set to the proper clearances and make note of the miles. Check it again in say 3-5000 miles. If everything is OK, they should still be where you set them. The '84 model is at the end of the era that got the bad metallurgy for the valve seats. BMW fixed the problem with new seats in 1985. If your clearances continue to close up, then you'll need to replace the valves, seats, and guides sooner rather than later.

Click to expand...

I've owned the bike since last season. This is the first time I'm addressing the various maintenance issues. I put about 3K on it last season without being stranded. Performance seemed good but when I was riding with my buddy on his GS, he would routinely leave me in the dust at higher speeds. When I purchased the bike I was unaware of the valve seat recession issues but I know now that I eventually may have to get the heads redone. I just want to be sure I'm doing it right. The engine is stone cold right now and ready for a proper adjustment. Just to verify, I should rotate the motor until the _mark beneath the OT is centered in the window just after the intake closes? We are talking left side here. Correct?

FYI here's another method. your spark plugs are out right? right, otherwise you couldn't turn it over. place a phillips screwdriver in your sparkplug hole and slowly turn your engine over. when the piston is at the top, check both sides for looseness. I had this same problem, and the screwdriver method worked better for me.

If my memory is correct here, rotate the engine taking a look at which valves are moving. Adjust the opposite side that is moving. If I'm incorrect here, I'm sure there will be plently of people speaking up.

Since the valve had closed up, I would check at 500 miles. If ok go to 1,000 miles. If ok, then I'd go to 3,000 miles etc. It doesn't take that long to check them, and it takes a bit longer to adjust them.

That's my $0.02.

Geoff_in_MN said:

Just to verify, I should rotate the motor until the _mark beneath the OT is centered in the window just after the intake closes? We are talking left side here. Correct?

Click to expand...

Works for me...I just did my /2 this weekend with the same method. To totally know for sure, you could remove the spark plug, plug the hole with your finger, and turn the engine until you feel pressure against the finger. Then turn to OT. But, watching the intake valve start to close is basically the same thing.

If, as noted in your first post, "the pushrods turn freely", then there is not significant pressure on the valve springs so you do have gap - no matter how small.

I would get out a good feeler gauge set and see what will slip in there. You won't feel much wiggle on the rockers at .001" - but there is clearance. Not enough, but .....