Topic: top end tapping

[76 k]

i know this may sound repetitive, seeing previous posts about this topic, but here it goes.
i have a 76 k6 and the top end is making a tapping sound after warmed up, when changing gears at a higher rpm, or doing around 50 mph or more steady. it it like a overlapping tapping when changing gears. or downshifting.
here is what i done so far:
-ran motor with tappet covers off, oil coming out of all.
-removed valve cover to visually inspect cam and such. everything looks ok, not the best, but ok. some light scoring on #2 inlet cam lobe. other than that, everything nice and wet.
-i have checked valve lash six times including when i had cover off.
-removed exhaust and replaced all gaskets.
-replaced all spark plugs and gapped correctly
-recent oil change with 20w 50 including filter
-removed carbs and check boots for cracks
-bench synched and cleaned carbs (round tops with velocity stacks)
-removed cam chain tensioner mechanism. was clean but stuck.
-adjusted cam chain tensioner
-replaced carbs and vac synched
-gapped points
-static timed
-strobe timed
-added seafoam to gas, and lucas treatment to oil
still tapping. what gives?
i plan on checking the valve lash tommorrow one cylinder at a time per a post i just read, instead of the the way the manual explains.
if anybody has any other hints or suggestions, i sure would appreciate any imput.
thank you

[76 k]

well, i ripped out the cam the other day, and all lobes were pretty rounded off. number three intake lobe was totally ground down and squared off. replaced the cam with the one outta my 75. also replaced all rocker arms, bearings, rocker arm spindles, cam towers, and both orfices. previous cam towers were scored pretty bad. removed exhaust, oil pan, cleaned screen, new gaskets everywhere, and some fresh oil.
started her up today, and she is running beautiful. still need to check timing and richen carb mix. running a little too lean. light tick from left side of motor. will be checking valve lash again tommorrow. bike has never run this solid.

[KingCustomCycles.com]

It is amazing what kind of power is developed when the intake and exhaust valves actually open. :-)  You will be good to go for 25 miles, then clean the oil system again. 

[76 k]

yeah, i didnt even plan on going that far. 3 miles to check today, valve adj tommorrow, and another 3. then change. there was no metal in the pan or on the pump screen. just some metal dust in and around the filter. same stuff ive seen on occasion. i assume that this has been an ongoing problem since i bought the bike, and it just finally went way too far.

[Grabcon]

When I have these clicks and tapping noises I rely on my good old screw drive. Typically one long enough to keep my face away from anything hot. I use it like a stethoscope while the motor is running. It is amazing what you here. I just move the screw drive tip from spot to spot with the handle at my ear and listen for the noises. This is a rely fast way to isolate a noisy tappet, Cam chain, etc.

What it won't find is an exhaust leak at the head. I have had two bikes now that leak where the header meets the head. A very annoying ticking noise.