Motorcycle Repair/hondacb160 1965
When the bikes ticking over it sounds like the clutch is making a grinding noise yet when you pull the clutch in the noise is gone.yet you can rev the bike with the clutch pulled in and its still quiet.then release the revs let clutch out the grinding noise is back its a nice smooth clutch doesnt jar you when pulling away when took clutch found 1 bolt loose could that have been problem
Adrian, You didn't state which bolt was loose, so it is a bit difficult to troubleshoot your question in some regards.
Generally when there is clutch related noises which quiet when the clutch is disengaged are due to looseness of the outer clutch basket on the input shaft, missing snap ring, or inner clutch hub being loose on the shaft.
Clutch hub and associated parts
Primary gears were changed at the engine serial number, perhaps to adddress some of the primary noises you are hearing. Usually these parts make more of a rattle than "grinding noises" so that is a little concerning. If the outer crankshaft nut isn't secured properly, the primary gears might start a bit of walking around and in worse cases, the oil filter can work loose on the end of the crankshaft and start tearing up some of the outer cover parts.
Check the fit of the inner clutch hub on the shaft, as well as the outer clutch basket for a loose gear on the back, excessive rocking movement on the shaft and security of the primary gears. If you have a lot of fine aluminum filings or dust in the oil, then something serious is happening that may require a whole engine teardown to resolve.
There are also issues with the transmission bushing locating pins shearing off, which causes misalignment of the transmission gears which would also make serious noises.