Noise in exhaust valve area 2000 km after rebuild.

While riding i had a loss of power when i pulled over i heard a metallic pinging sound. I localized it with a stethoscope to the exhaust area on the head, the sound can't be heard over 2000 rpm. I removed the valve cover and inspected lash. Intake 0.15 exhaust 0.20. (Stage 2 hotcams, Kibblewhite valves, MCCT, CW BB kit, new timing chain, all 2000 km ago) I removed the cams and inspected only to find no anomalies except a thin black film on the cams. Then engine has been running beautifully since broken in. I found some lateral play on the exhaust decompression valve http://vid409.photobucket.com/albums/pp174/rukik/20150810_150818_zpsnpfjta2d.mp4 . I don't know if this could be the sound or if it is an exhaust valve. Would a valve make noise and still allow an engine to run? or are they like a one shot deal, where if the go that is it? 

if the lash is good and it runs fine i wouldnt worry too much about the valves themselves ..  i would check it good for an exhaust leak to, ive had that sound like anything from a tick to a knock . not sure about the decompression thing ...

Thanks for the reply, I will double check the exhaust donut maybe that's the culprit. Those videos are good thanks for posting. The second one shows the centrifugal arm moving, on my cams case it seems the whole thing moves, like the retaining clip is to small of something.

While riding i had a loss of power when i pulled over i heard a metallic pinging sound. I localized it with a stethoscope to the exhaust area on the head, the sound can't be heard over 2000 rpm. I removed the valve cover and inspected lash. Intake 0.15 exhaust 0.20. (Stage 2 hotcams, Kibblewhite valves, MCCT, CW BB kit, new timing chain, all 2000 km ago) I removed the cams and inspected only to find no anomalies except a thin black film on the cams. Then engine has been running beautifully since broken in. I found some lateral play on the exhaust decompression valve http://vid409.photobucket.com/albums/pp174/rukik/20150810_150818_zpsnpfjta2d.mp4 . I don't know if this could be the sound or if it is an exhaust valve. Would a valve make noise and still allow an engine to run? or are they like a one shot deal, where if the go that is it? 

 

As the cam rotates, the ADM (auto decomp mech) will CLICK. This is normal for each rotation at slow speed. The cam spinning >1500 should make the ADM expand and be quiet, assuming the ADM is not worn out. 

 

If you pull the cam and try to rotate the ADM vs the cam, in your hands, you should find very little (if any) rotational movement BETWEEN the ADM and the cam. In other words, it should be tight, except for the arm that moves out with increased engine rpm. If it rotates on the cam more than barely perceptible, cut it off. 

 

The lateral movement varies widely from bike to bike. Some are .005" others are .050". It's not a concern to me. 

Thank you Ohgood I'll check that next time it's open. Listening to the noise again it's not a constant noise with each rpm, say like piston slap or a loose cam chain. Ill check for the play your refering to next time I dive in. The cams have 2000 kms of street riding on them so I hope I didn't end up with a faulty cam. Would a slight exhaust leak at the head make this type of noise?

Thank you Ohgood I'll check that next time it's open. Listening to the noise again it's not a constant noise with each rpm, say like piston slap or a loose cam chain. Ill check for the play your refering to next time I dive in. The cams have 2000 kms of street riding on them so I hope I didn't end up with a faulty cam. Would a slight exhaust leak at the head make this type of noise?

 

yuppers. even at the joint between the header pipe and tail pipe, you can get a very similar noise to loose valve clearances. piston slap similarities would be at the joint between the head and header pipe. the closer to the head, the sooner you'll want to shut off the bike and investigate, because how nasty it sounds. ;-) 

I was lucky it happened when I was about 500 meters from my house. I pulled over, heard the sounds and started pushing Haha. I'll order a new exhaust donut and try before I start going into the head. The sound is comming from the exhaust cam area for sure, and it's more defined while my stethoscope is on the exhaust port just off the head, on the engine side of the header joint.

Further Diag,

 

Got the exhaust clearance as close to 0.16 as possible, I changed the exhaust gasket incase the sound was it leaking. Its still present https://onedrive.live.com/redir?resid=8C40B8D2185C08AC!245&authkey=!ACD6cUDmcV5OIqU&ithint=video%2cmp4

 

Also I noticed there is some oil in the exhaust port of the head coming from the valve on the opposite side of the cam gear. The valve seals are new when the valves and springs were changed, it passed a leak test at that point, what would cause this? http://i409.photobucket.com/albums/pp174/rukik/20150815_133429_zpsk4p62hhk.jpg

Further testing. I put the stock exhaust cam in that has allready has the decompression lever removed. Started and the noise is gone. I removed the decompression lever from the hotcam because it was loose, reinstalled and started, the noise is there again. The hotcam has a higher lift, could the valve be hitting the piston? If I change the exhaust cam timing one tooth would it run and maybe close the valve earlier?

Just guessing here, but it seems like something has caused the valve guide to migrate upwards on that one valve, and the bottom of the spring retainer is hitting the top of the valve guide / valve seal. Or (long shot here) there is something wrong going on with the cotters and or spring retainer on that one valve. Pull the exhaust cam and both inverted buckets and compare from valve to valve the distance from the top of the valve stem where the shim sits to the top of the spring retainer. Perhaps a cocked valve cotter? Don't try to skip teeth to alter the valve timing. You had something fail or move to cause a sudden loss of power. You need to find what that was, not make adjustments to make it go away. If you suspect the valves are contacting the piston for any reason, do not continue to run it that way. Keep in mind that a valve failure almost always makes a huge expensive mess out of the head and piston. A valve that is contacting the piston will eventually fail from fatigue.

Thanks for the reply, I will check that out after work and see if there is a difference and post my findings.

 

It started raining, and I don't have a garage so this will have to wait...

Edited by Rukix

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