Re: what is my noise?

Posted by mmorri on
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/what-is-my-noise-tp2541021p4053161.html

Unless it's an input shaft issue on the transmission, it's not drivetrain related.

When I spoke about road speed it was just to illustrate how I deal with the problem when I'm on the freeway.

It makes the noise in all gears and in neutral with the clutch in or out.

Again, I've checked and adjusted the timing chain and checked the clearances in the cam/valvetrain.  All of the valve springs appear to be good.

I can't believe it's a rod bearing as it'd make the noise for a much wider rpm range and frankly, the engine would have died long ago if it were a bad rod bearing.

I was hoping someone had found that the pipes had a baffle that can break free and resonate at the right rpms or that some ignition/timing glitch could cause it.

It's a definite knock and not the kind of sound a slapping chain makes.  It sounds like a bad rod.  It's too loud to be wrist pin slap.  I'm kind of at a loss.

On Thu, Aug 14, 2014 at 5:50 PM, LukeM [via Honda CB750'S] <[hidden email]> wrote:

IF it's a cam chain noise, it would do it in all gears and neutral, assuming you're able to hold the throttle at the exact RPM  that makes the noise. You can also check this by getting up to the target speed in 5th, then downshifting to 4th, and revving up to get to the target speed. If it does it ONLY at 55-59 MPH, then there's a good chance it's drivetrain related (like the drive chain slapping or somesuch).  Maybe a cable that's flapping in the wind?

Hope this helps.
Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.

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