Top Engine Noise and Ping

[probablynotnick]

Hey everyone, I'm in the process of overhauling my GS650G. I've gone through and cleaned, bench, and vacuum synced the carbs as well as adjusted all my tappet shims to be within the .03 to .08 tolerance. The mixture screws are out 2 1/2 turns from lightly seated. Now what I am noticing is a ping or ringing sound near the top right of the engine. I can only notice it at idle, and it tends to "settle" into the ringing. There is also a tapping/knocking noise up there too, which may be the infamous "cam walk"

I want to learn as much as possible, so please feel free to info barf all over this post.

Here's a video I took that illustrates the ping/ring sound I'm talking about. This is after the bike is nice and warm.

https://www.youtube.com/watch?v=BncS6NKMp_8&feature=youtu.be

The bike also doesn't really like to idle below 1500. It gets rough, wanders lower and dies. I'm thinking I might have to pull and dip the carbs again and pay special attention to the idle circuit, as she dogs at low rpms but settles in and screams as they climb.

Thoughts?

 

[tom203]

Top right on engine? I hope this ain't a #4 rod bearing problem like member William Groebe (in this same category) has been fighting.
if all is well mechanically and carbs are perfect, this thing will idle nicely at 1000 rpm, but 1200 is safer.

 

[storm 64]

Are you sure the sound is coming from the engine? I had a knocking type sound coming from my 850. It turned out to be just low on fuel. The float on the fuel gauge mechanism was vibrating on the bottom of the tank. I would rev the engine up, and the knock would increase. Scared the heck out of me... Good luck

 

[storm 64]

Also, on the the topic of engine noises. If you ever had a loose exhaust header pipe, it sounds like a very loose valve. I have a story about that, that I'm not going to get into... Also a loose gas cap, I chased that rattle for about two years. I could swear it was coming from the instrument panel. Turn out to be a weak spring washer on the cap. My point is, a lot of times it's not a engine noise at all...

 

[probablynotnick]

Thanks for the replies. I might pull the header and try that just in case, but I do think it might be more than that unfortunately! Is there anybody in the Portland area that could come have a look at it? I'll reward the kindness with some of my homebrew! That, or if anyone knows a reputable mechanic who might point me in the right direction. I'm really just looking for information so that I can do the work myself.

This forum has provided a TON of help getting my bike happy. Nothin but gratitude here! Thanks!