That knocking sound...

[sambler]

I've owned a 1995 R100RT for a several years and I ride it monthly or so. The bike has 29,000 miles on it and has been well cared for, cosmetically. Early on, I had some clatter from the rocker arms, so I inspected things carefully while adjusting the valves. I found that the roller bearing cage had been destroyed on the right exhaust rocker. Bearing rollers were coming out of the split in the rocker arm clamp and a couple were laying in the valve cover. When I went to the left cylinder, I found the same issue with the intake rocker.

I ordered new rockers with bearings from Max BMW and installed them. Once I overhauled the carbs, got the proper jets put in, the clip at the right location on the needle, and the valve gap and rocker shaft endplay adjusted, the bike now runs well. However, there is a loudish clatter, almost a knocking, from the right cylinder.

I recently took the bike on a day-long 200-mile jaunt at 65-70 mph and everything went smoothly, as long as I don't care about the noise. I have checked all the settings and everything is spot on.

I don't know where to go next. Any thoughts from you guys? Appreciate any thoughts you have!

 

[GTRider]

Were the rocker shafts replaced or measured/inspected when the rockers were replaced, and are the pushrods reasonably centered in their tunnels? And were the associated lifters removed and inspected?

Best,
DeVern

 

[sambler]

Were the rocker shafts replaced or measured/inspected when the rockers were replaced, and are the pushrods reasonably centered in their tunnels? And were the associated lifters removed and inspected?

Best,
DeVern

Thanks for the reply, DeVern.

Rocker shafts were not replaced or measured when the rockers were replaced. Push rods are not centered enough for me, but I am a bit overzealous when it comes to such things. I did look at them carefully to see if I could center them better by moving the rocker shafts a bit. Not much luck there. I did not remove and inspect the lifters. Can that be done without removing the jugs?

I'm kind of resolved that I may need to go deeper to solve this riddle. Part of me wants to take the cylinders off, have the heads done, everything else measured/inspected renewed as necessary, but I hate to if I don't have any indication that there is really a problem. Is there any testing I can do with the engine basically intact? Will compression test/leak-down test tell me anything? This has been my thought for next steps.

 

[pauls1150]

Some lifters (aka tappet, cam follower) can be pulled out with a magnet, but I don't know if that applies to BMW's airheads. (Side note - if they can be, you'll need new rubber seals at the pushrod bottoms.)
This "shouldn't" apply to yours, but BMW did update the tappets from an angled "window" to a straight window, because the angled ones were cracking.

 

[GTRider]

At 29k the valves should still be just fine, assuming proper valve clearances were maintained during that mileage. Compression and leak down tests would help verify that. However, depending upon how long the bike was run with a bad needle bearing it’s certainly possible that some wear has happened to the affected guide(s). Inspecting the lifters would require removing the affected cylinder(s) and heads. Ditto for the rocker shafts. The only reason I inquired about the lifters is because a disintegrated needle bearing can possibly induce some harsh action at the lifter end, which in turn could leave a pitting or cracked lifter. But before getting into tearing things apart I’d suggest investing in an automotive stethoscope and do some exploring for the exact source of the noise, both hot and cold. Diagnostic surgery should always start with at least a rough idea of what part(s) should be operated upon.

Best,
DeVern

 

[AntonLargiader]

You mentioned setting the rocker end play. Did you need to re-shim it? I would start by verifying that the rockers turn freely if you back the adjusters out all the way.

If the rockers really are set up properly, the problem probably is the guides. Those late R100 models with the 30º valve seats had loose guides from the very beginning. 29k is not too early to have a problem with that. I replace those with 45º valves when I replace the guides.

 

[sambler]

At 29k the valves should still be just fine, assuming proper valve clearances were maintained during that mileage. Compression and leak down tests would help verify that. However, depending upon how long the bike was run with a bad needle bearing it’s certainly possible that some wear has happened to the affected guide(s). Inspecting the lifters would require removing the affected cylinder(s) and heads. Ditto for the rocker shafts. The only reason I inquired about the lifters is because a disintegrated needle bearing can possibly induce some harsh action at the lifter end, which in turn could leave a pitting or cracked lifter. But before getting into tearing things apart I’d suggest investing in an automotive stethoscope and do some exploring for the exact source of the noise, both hot and cold. Diagnostic surgery should always start with at least a rough idea of what part(s) should be operated upon.

Best,
DeVern

I'll bet the bike was run for a good bit with the bad needle bearings. I've been surprised at what I have found while putting things right on the bike. I will move forward with compression and leak-down tests, so as to have base-line numbers. I won't be surprised to find worn valve guides, as you suggest, and as Anton discusses in his reply below.

Again, thanks for the discussion.

 

[sambler]

You mentioned setting the rocker end play. Did you need to re-shim it? I would start by verifying that the rockers turn freely if you back the adjusters out all the way.

If the rockers really are set up properly, the problem probably is the guides. Those late R100 models with the 30º valve seats had loose guides from the very beginning. 29k is not too early to have a problem with that. I replace those with 45º valves when I replace the guides.

Hi Anton,

Enjoyed your tranny talk at Super Tech a couple years ago. You simplified things considerably for me!

I did not need to reshim the end play. Each rocker turned freely when backed off. single shim allowed a .05 gauge to fit tightly, so I felt ok about that.

I will be performing a leak-down test in the near future. Hopefully, that will give some clarity. Anything else you suggest in order to check the guides? I really need to replace the pushrod shaft seals, so head work would be easiest at that time.

Thanks for your comments!

 

[AntonLargiader]

You really need to pull the head off and remove the valves to know. It is quite possible that the valve seats will look awful. On the Valves page of my website you can see a bad example. The complete fix is new guides and new 45 degree valves.

 

[sambler]

You really need to pull the head off and remove the valves to know. It is quite possible that the valve seats will look awful. On the Valves page of my website you can see a bad example. The complete fix is new guides and new 45 degree valves.

Yeah, I can see that. I did see the one on your web site. Crazy if that thing still ran!