weird engine noise

[minipete]

New to this and not very computer literate, but I am stuck on this one and wondered if anyone has experienced this. Post a rebuild on YPVS 31K with re-bored top end pistons rings etc, the engine warms up normally and once the thermostat opens after about a mile or so this odd hooting noise develops. if I slow down it disappears and re-appears when the revs increase after another mile or so. I suspected a gasket leak so changed it, and changed it again. confirmed coolant flow, functioned thermostat, NDT the head with no cracks refitted head with gen head gasket at extreme cost, and no change. Oddly no leaks apparent and engine runs normally in all respects (still running in though under 6k rpm. Now I,m starting to wonder is this an internal gas leak at all? I am willing to sell my eternal soul to get this sorted!!!!!!!!!!!Help

[marsbar350]

its not a cable driven speedo on these is it
they some times make a noise

[minipete]

they are but audible over the noise of the engine? and I cant recreate it on the drive way so its worth a try, thanks.

Taken me ages to get some time on the bike but I can confirm it was a noisy accelerator cable, many thanks to the chap who steered me in the right direction, never would have found it otherwise!

[midlifecrisisrd]

Hi,

On the 31k if the tacho or the speedo are on the way out they can howl or scream. Get in to the moving parts with some wd40 and see if it goes away.

Steve