Three C-10's and countless valve clearance adjustments in 32 years of preventative maintenance and no more. The last adjustment on my current ride was done at least 20,000 miles ago and I found two valves (both intake) slightly loose. All others were still spot on. That's usually the case; spend hours getting the plastic off, extracting the #^%$! valve cover, adjusting and reassembly. I can't recall ever finding anything out of whack enough to justify this job. There's more of a chance of collateral damage going in and checking. (on edit: maybe the first 6,000 miles to account for break-in)
A few observations:
1) GTR valve covers have no dowels to secure the spark plug seals. There are shallow holes in the casting but they're too large for the dowels I ordered. Instead I used 3M Weatherstripping adhesive and sealant. It's labelled to seal gaskets too. I applied this yesterday to the narrow channels for the perimeter gasket and the doweless spark plug well gaskets. It sat overnight and held the gaskets in place during reassembly.
2) Some C-10's allow for easier cover removal and replacement. The current ride does not. Maybe the fairing frame sits lower on some. A clamp on the coolant hose above the cover can be rotated so the worm gear is on top instead on the bottom (I did that long ago but still no joy). The GTR cover went in easier than the original came out though.
3) I have been adjusting all valves with the lobes at 12:00. The timing cover remains in place. I can't understand why this method would not work; clearance is clearance.
4) Whatever tool or part I'm looking for is always on the other side of the bike.
5) Lead acid plate batteries last about 3 years now. They used to last much longer. I ordered a AGM battery and will see if it's any longer lasting. Usually when these batteries fail there's no telltale clues; one day the bike starts fine, the next day it doesn't.
6) It's always good practice to start the bike and check for leaks before replacing all the plastic after reinstalling the valve cover. A common place for a leak is along the front edge where the foam rubber air deflector can dislodge the gasket when it's reinstalled. I found that applying some force to move the air deflector away from the engine helps. Over time the air deflector pushes back and conforms with the engine and cover shape.
A few observations:
1) GTR valve covers have no dowels to secure the spark plug seals. There are shallow holes in the casting but they're too large for the dowels I ordered. Instead I used 3M Weatherstripping adhesive and sealant. It's labelled to seal gaskets too. I applied this yesterday to the narrow channels for the perimeter gasket and the doweless spark plug well gaskets. It sat overnight and held the gaskets in place during reassembly.
2) Some C-10's allow for easier cover removal and replacement. The current ride does not. Maybe the fairing frame sits lower on some. A clamp on the coolant hose above the cover can be rotated so the worm gear is on top instead on the bottom (I did that long ago but still no joy). The GTR cover went in easier than the original came out though.
3) I have been adjusting all valves with the lobes at 12:00. The timing cover remains in place. I can't understand why this method would not work; clearance is clearance.
4) Whatever tool or part I'm looking for is always on the other side of the bike.
5) Lead acid plate batteries last about 3 years now. They used to last much longer. I ordered a AGM battery and will see if it's any longer lasting. Usually when these batteries fail there's no telltale clues; one day the bike starts fine, the next day it doesn't.
6) It's always good practice to start the bike and check for leaks before replacing all the plastic after reinstalling the valve cover. A common place for a leak is along the front edge where the foam rubber air deflector can dislodge the gasket when it's reinstalled. I found that applying some force to move the air deflector away from the engine helps. Over time the air deflector pushes back and conforms with the engine and cover shape.