Quick Valve (Pre) Adjustment Question

[foobar]

When the rocker-to-valve stem clearance on the oilhead "go out of spec" and require adjustment, which way do they tend to go-- tighter or looser? Common sense would say looser, correct?

The reason I ask is that mine were cranked down with no gap before the adjustment procedure. The bike is used, so I have no idea how long they were that way, but now they they have been adjusted, it runs much smoother-- so everything must be ok.

Just curious if this is a condition to watch for. Thoughts? Comments?

TIA

PS- 2002 R1150R w/o ABS

[riceburner]

Mine seem to go tighter or looser at random (I check em every 12,000). I can look back in my records to see what if there's any sort of pattern if neccessary?

[Oilhead]

I just checked my records. It had loosened slightly at each interval, 6K miles, 12K, 18K, & 24K. I have 27K miles now.

[foobar]

Thanks for the replies.

The previous owner said the local BMW cycle dealer had done all previous maint, including the last valve job. The only conclusion I can make at this point is that the dealer did it (very) improperly.

[grwrockster]

I've always understood it that valve clearances shouldclose up over time rather than loosen. This is as the point where wear is most likely to occur is not on the cam lobe, pushrod or valve stem, but on the valve seat. The valve opening and slamming shut against the valve seat is effectively a small hammer. the valve closing up is actually the vlave head being able to 'sink' into the seat slightly. This in turn moves the valve stem closer to the rocker, and reduces the clearance.

Left long enough, the valve clearance erodes entirely - this means that the valve can't colse 100%, so there is a not an perfect seal between valve and valve seat. This leads to compression loss and buring out of the valves - heads off for new valve seats and new valves etc.

If a valve has a wider clearance than it should have when measured, then as aa generality I'd have guessed that would be as a result of it not being done correctly (assuming nothing is loose!

[Sunbeemer]

When I have found a valve not in spec (and that is less common after the first 12,000 miles) they've always loosened by 0.0005" - 0.001"/6000 miles. Now, after 40,000 + miles, I might find 1 or 2 opened up a half thousandth between adjustments every 6k-8k miles.

[garr2]

I've always understood it that valve clearances should close up over time rather than loosen

That was my understanding of what to expect too.
I have only kept records for the last 2 services - the ones I did myself - and like Sunbeemer I have found that they tended to loosen by about a thousandth of an inch.
What have other people found and if there seems to be a generally loosening what could be the explanation?

[foobar]

Well, I guess I have to retract my slam of the dealership. Half report looser and half report tighter...