breakage of rocker arms; valve gear; pushrod tubes;
various parts of the cylinder heads.
For BMW Airhead Motorcycles
© Copyright 2019, R. Fleischer
Article 60, sub-section 6
Adjusting valves & rocker end play, etc, will be found in article #40:
If you have INsufficient adjustability to set valve clearance, after milling the head, article 60 section 5:
There is more top end information in article 60 section 1; article 60 section 5; article 60 section 8.
I suggest you read them!
BREAKAGE OF ROCKER ARMS:
This is a rare occurrence, and usually only happens under racing conditions, such as with very high rpm, and/or high lift cams, increased valve spring strength, insufficient spring clearance at maximum lift, etc. However, it did happen, but rarely, on stock early Airheads, in non-racing use, and only in the /7 era, as far as I know. If you look closely at a rocker arm, immediately next to where the ADJUSTOR screws into the rocker arm, the web width there on the suspect rocker arms is about 7 mm wide. BMW made a production change and the rockers with the factory change had a 11 mm width. There was no change in the rocker part number. It does not appear to be a formal re-call by the Factory. I am not listing all the rocker part numbers, except two, because:
1. No new rockers are available that are 7 mm.
2. It is easy to confuse yourself over the SEVERAL part numbers used for the rockers. The original part numbers, long gone now, were 11-33-1-262-403 and -404.
3. You can measure your rockers.
Rocker Arm Shafts & Rocker Arm Needle Bearings:
This section does not apply to the /5 series, which used bushings in the rocker arms, not needle bearings. I discuss the /5 series separately in this article.
In working with the valve gear, and not doing a bearing replacement, I recommend you do not disassemble the rocker arm shaft area unnecessarily ...as if pulled far enough out, some tiny roller needles may fall inside ...or on the floor. The needles are located at each end, arranged as a bearing. The proper amount of needles at either end is just enough so one more will not quite fit. I will get deeper into that later here, because there are two types, meaning two numbers of needles, and some other things to explain. The center area is empty.
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