Scarry thoughts ~ bottom end rattle/s or what?

May 22, 2004
How would you describe a bottom end rattle ? (OR ~ what is this sound!)

I have a machine which is emitting a audible tapping on idle ~ which on the face of it sounds like it is coming from the primary cases !!!!!!!!!

This tapping sounds more like rocker / tappet (single) rattle but is somewhat louder than the still audible rockers.

By sticking a rod on the crankcases there is nothing to be heard ~
but at the point of the timing access plug ~ there it is distinctive, even to the point that this the only place it can be heard via a 'rod' .

The best description or comparison I would make would be my Ford EFI six cylinder which DOES have a cam follower which sometimes causes a tappet clacking on start up.

This sounds exactly the same!

(I realise that alloy cases are deceiving ~)

The engine was rebuilt some 5,ooo miles ago ...

I overhauled the primary about two weeks ago and replaced the clutch hub bearing ~ :shock:


"Sons of Arthritus"
Jan 14, 2004
Country flag
Check the rotor. It may loose, tightens up on revs, knocks at idle.
Jun 14, 2003
And while you're in there, check the stator. I actually had a loose stator once and its symptoms were identical to what you've described.

May 22, 2004
Yes .. I am more than a little surprised I did not 'tweek' to this straight up .. well it was the day after the night before ~ 8)

The fresh oil showed distinct signs of black deposits, which I figure were caused by the loose rotor ~???? :twisted:

I had a look and tensioned up the rotor and checked the stator clearance , even removing and replacing it.

The perplexing part is the the clearance at the bottom between rotor and the stator was quite large. where as the top was minimumal ~!!! at <.007>

The stator is fairly new in fact , but the variance is of concern to me !

(More great British quality standards? )