After great deliberations I finally pulled the engine last weekend. I recently bought a timing light and realized I may also have timing issues related to this potential cam chain problem and decided it was time to just do it.
Some of the conversation relating to the timing issues have crossed over into another thread:
http://www.xs650.com/threads/cannot-stop-throttle-shaft-seal-leaks.54366/ (for reference), but I'm planing to focus on issues related to opening the engine on this current thread.
The cam chain guide was destroyed as everyone had predicted. with several 3" chunks resting in the bottom of my engine case and a 0.5mm groove worn into the bare aluminum of the guide at this point. I also had a thick aluminum paste in my side filter, compared to the very small chunks of black plastic scattered on the last few oil changes. I think the timing chain appears to be okay, but I'm going to replace it with the guide. I think I can keep the tensioner in its current condition at the recommendation of 5twins.
I honestly agree that most of my abnormal noise was the cam chain grinding into the guide/rolling across the broken chunks of plastic from it. While I have the engine open, I plan to give it all a once over though. Things seem fine as far as I can tell, but I'd love any advice I may have missed researching other threads on wear limits and replaceable items.
Rockers - Seem good. They are smooth to touch, but have discolored spots on them. Pulled and shined with #0000 steel wool. They appear to match the spec of the Clymer book. In this photo is one as found and one after I cleaned. Does this seem okay? I've had valve clatter that seems to come and go just as my engine timing. I'm assuming the new chain will fix that without replacing the rockers or cam?
Camshaft - Scratched, but I think just standard wear, not damaged. They are smooth to the touch. There are no deep scratches or pits on any of the surface. Bearings seem fine. First photo is "as pulled" and the second photo is after doing a light once over with the steel wool on cams only. The book says the spec for the cam shaft is
Standard Value:
Intake: 39.94-40.04mm ||
Exhaust: 39.98-40.08mm
Wear Limit:
Intake: 39.84mm ||
Exhaust: 39.88
Mine measures 39.8. My caliper only does single digit decimal. Is it recommended I take it for evaluation/more refined measurements or is it likely fine?
I have removed the valves, but not fully cleaned or measured yet. Hope to have some details on those and pistons soon. is it necessary to put the valve springs in a spring pressure gauge to check or is just measuring them sufficient? Also, I see Mike's sells and suggests valve shims? should I get a set of those while rebuilding? I'm assuming those just compensate for loss of spring pressure? My cylinder compression has seemed fine so far, with both matching just under 130 and just under 150 with 1tsp of oil added.
Hoping to soda blast the three pieces of the top end this weekend. Once I have all my ducks in a row up top, I plan to do a less invasive once over on the bottom end to cover my bases while out. I replaced the shifter shaft seal a week before pulling the engine and the case seal on the clutch side cover during last oil change, but It seems to have oil buildup on both frame bars under the engine after a few weeks of riding. Pushrod seal and crankshaft seal behind the rotor both seem fine? Not sure if the seal on the front of the crank case is leaking?
Any insights to share on any of the above would be greatly appreciated, as I don't yet have the hands on experience to judge part conditions beyond the manual's written notes.
Thanks in advance!