I recently adjusted the cam chain tensioner and performed a valve adjustment on my 1971 CB350K3. It was my first time doing these things. I did a few other maintenance items too. I don't think they're related to the noise I'm hearing, but just in case, I'll mention them: new ignition coils, new condensers, new regulator/rectifier, adjusted ignition timing. I did my best to do the valve adjustment as accurately as possible - top dead center on the compression stroke of each cylinder, 0.002 on the intakes, 0.004 on the exhausts. And I adjusted the cam chain tensioner at 90 degrees past LT. All these adjustments while the engine was cold. The engine starts right up and runs great. But I'm getting this noise. Please excuse the wind noise in the video - I'll try to shield the phone from the wind next time. It may be hard to hear in the video but the clicking you hear has a high-pitched component to it that (to me) sounds like a cricket chirping, except it's continuous and it gets louder with engine speed, especially under load. I think I can hear it even in the garage when it's idling but it's definitely much less noticeable. Even if I rev it while idling, it's much less noticeable than when the engine is under load. It's not the tachometer cable - I removed the tach and speedo cables to be sure it wasn't them squealing. Here's the dumb thing that I did that has me concerned about damage. The first time I adjusted the valves (I adjusted them twice because I was questioning whether I got them accurate enough the first time) I forgot to tighten the nut on the rocker arm of the right side exhaust, and I started the engine. It was making a fair amount of noise as the rocker must have been hammering the valve, and I let it idle for about a minute before I knew it wasn't going away and that something was definitely wrong. I don't see any obvious damage when I look at the valve stem through the inspection port. The only thing that makes me think that the noise might not be related to that incident is that I did ride the motorcycle for about a mile or two afterwards (after tightening the nut) and I don't remember hearing the noise until after I adjusted the valves a second time today. What do you guys think? Are the valves just adjusted too loosely? Would that cause a high pitched noise? Any other ideas what could be causing it? I'm hoping to rule things out before I take apart the engine to get a closer look at the valves and rockers.
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Is this loose valve noise or possibly damage?
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In the very beginning I hear what might be high pitched ticking, but after that it's 99% wind noise. Loose valves are best heard at lower rpm sitting still, and a loose cam chain would be as well. But please, when you take the video sitting still, stay next to the engine for longer than 2 or 3 seconds on each side. So many today already hear their noises and then video while constantly moving around, which makes it hard to get a good listen to one specific sound.
I won't be able to take another video until next weekend. In the meantime, I have this video from yesterday in the garage but I don't think it'll be much help. I don't think the noise is present here. But maybe you'll hear something that I don't hear. It's loudest on the road. I'll try to get better video next weekend. But the best way I can describe it is like a constant cricket noise - that same pitch. It nearly goes away during a gear shift when I'm rolling off the throttle.
Hard to be sure from that but the valves do sound a bit 'ticky' even in that short clip.
Did you by chance do anything with the exhaust during your maintenance work? It's certainly a little loud and given the fact that it follows the RPM could also be a really small exhaust leak at the head - it's not the exact right sound for that but phone mics are tough.
I'd also check that one tappet adjuster that was left loose. Sometimes that can cause the tappet adjuster itself to take on some thread damage and get a bit "wobbly" in its adjustment. I'd back it all the way out and inspect it to eliminate easy stuff.
Curious on the cam chain adjustment - 90 past TDC on Left is what the Houston Bros video uses... the service bulletin for the spring-loaded tensioner for the later 350 models is 90 degrees from TDC on the right. (Unfortunately not covered by the most common FSM copies floating around as those reference the hydraulic adjusters.)
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I'd also check that one tappet adjuster that was left loose. Sometimes that can cause the tappet adjuster itself to take on some thread damage and get a bit "wobbly" in its adjustment. I'd back it all the way out and inspect it to eliminate easy stuff.
Curious on the cam chain adjustment - 90 past TDC on Left is what the Houston Bros video uses... the service bulletin for the spring-loaded tensioner for the later 350 models is 90 degrees from TDC on the right. (Unfortunately not covered by the most common FSM copies floating around as those reference the hydraulic adjusters.)
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Interesting, I hadn't seen that version. Does make you wonder if the translation of left and right side might have been involved.
Likely due to the number of times the word "Left" is used, along with the rotating counterclockwise, then clockwise. All to get to 90 past the right cylinder.
Wow, I wonder if that's the problem. Thanks for uploading the bulletin. I had been using my service manual but it was definitely for the hydraulic tensioner - I remember that the diagram of the tensioner was the hydraulic one. I didn't realize that the procedure was different for the spring loaded tensioner.
And now that you mention it, I did see a bit of smoke coming from the area where the right header connects to the muffler. I'll check that out too, but I'm guessing the tensioner is the culprit if my adjustment is that far off.
I don't hear cam chain noise in your short video, but I'd still recheck the adjustment.