Topic: Anyone able to identify what this rattling sound is?

[Frrrrunkis]

http://wolf103.com/cb400f1.mp3

Is that the sound of a rattling cam chain, or something else?
1975 CB400F

[kach_me]

Can't hear it for some reason. 

[Frrrrunkis]

oops, accidently uploaded an alias to the file instead of the actual file
also another recording of it before I fixed the muffler. http://wolf103.com/cb400f.mp3

[oldbiker]

To me that does sound like camchain. I presume you have a manual, so go through the adjustment CAREFULLY.

[jonbuoy]

Sounds fit other than that rattle - what pipes you have on there?

[Soos]

I would say it sounds like the camchain as well.
Had a twin 400cc that sounded like that after a few hundred miles.
had to adjust a lot, but it was the origional chain, and the bike had very high milage.

l8r

[Frrrrunkis]

it's stock pipes, when I got it the muffler had been separated where the 4 pipes joined into one, had to take a jack and push up on the muffler to get it to join up. looks like the PO tried to weld it back together, but just left a blob of weld there instead.

I've tried the chain adjustment and it didn't do anything, so I guess the arm is stuck

[Tim2005]

Yep, definitely the camchain, and pretty bad too. Either the arm is stuck or the chain is very stretched. If the chain is really badly stretched they can sound like that even though the tensioner is AOK.

[Bodi]

Don't give up yet. The tensioner adjusting springs go weak with age and the thing just doesn't work per the manual procedure any more, even with a perfect knuckle.
Just remove the cap bolt above the adjuster bolt, loosen the adjuster, and push down on the adjuster rod through the hole above with a small screwdriver or a 3" nail. That usually helps the springs enough to tighten the chain. Yours does sound pretty loose and may have eaten into the knuckle, of course, but if not you save the trouble of removing and splitting the engine.
Nothing comes out when you remove that cap bolt (except the bolt of course), the springs are in further.

[Frrrrunkis]

wow that is one tough to reach bolt. (the cap bolt, not the adjuster bolt) especially when the pipes are hot. I tried getting to it for 10 minutes before I finally touched my arm on a hot pipe and left a nice little burn. I guess this will have to be worked on at a later date.

[Bodi]

It's a real bugger to get back in too
I tape it to a socket.
Not a good job on a hot oven. You can leave the cap screw off and ride a while, making whatever adjustments you need and replacing it after the engine is either quieter - or scheduled for a teardown - and has cooled off. The cap bolt just keeps water out to stop the works from rusting up as far as I can tell, oil doesn't gush out or anything like that.

[Frrrrunkis]

I got out there this morning after finding a couple of socket extensions, got the plug out and tried pushing on a screwdriver down in there, wouldn't budge. Got a hammer and tapped on it a few times, and right then it sounded like a whole new bike. Just a slight little hiss and the sound of the muffler is all I hear now. I've never worked on any kind of engine in my life. Without this place, I would have never figured it out! Thanks guys!

http://wolf103.com/cb400f2.mp3 The hissing sound actually isn't as loud as the recording makes it out to be, I had the laptop sitting right next to it when I recorded it