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Re: Mystery Debris

Posted: Tue Aug 22, 2017 1:45 pm
by simon.holyfield
A few more pictures. It's about 3/32" thick and about 1/4" on the ID:

IMAG0027.jpg
IMAG0026.jpg
IMAG0023.jpg


Next step is to get the endoscope into the rocker boxes...

Re: Mystery Debris

Posted: Tue Aug 22, 2017 9:16 pm
by paul.jameson
Simes,

I'm confused. Can we have some photos using an imperial (inches) ruler please?

Re: Mystery Debris

Posted: Tue Aug 22, 2017 9:29 pm
by simon.holyfield
Well I was going to do that, of course - but that ruler only has 1/8ths and the fragment is quite small!

Re: Mystery Debris

Posted: Wed Aug 23, 2017 5:29 am
by adrie.degraaff
I have looked at several followers, the thicknes of the wall varies with the years and machining.

I think it's the red line part, wich can only brake in a vice not by normal use.

It seems like the broken edges where already rusted before it went in the crankcase.

Also your sprocket has heavy wear from to strong valve springs or to soft sprocket.

Re: Mystery Debris

Posted: Wed Aug 23, 2017 7:02 am
by nevhunter
It's a piece of the follower. You can see the thicknessed bit in a part of the edge that runs around the place where the die or mould meets. Nev

Re: Mystery Debris

Posted: Wed Aug 23, 2017 8:33 am
by simon.holyfield
Thanks folks. It's great to have so much experience to rely on, and again from opposite sides of the world!

On the cam, I see the wear in the teeth - I've been looking for cams since John Nash made this post viewtopic.php?f=48&t=6511

As to the follower, I have some free time tomorrow evening - it shouldn't take long to get in the gear case again!

Thanks again.

Re: Mystery Debris

Posted: Wed Aug 23, 2017 3:39 pm
by adrie.degraaff
simon.holyfield wrote: I've been looking for cams since John Nash made this post viewtopic.php?f=48&t=6511

I have the cam and sprocket you want in almost NOS condition, the problem is, what to ask if half the club is looking for them.
A set of useble followers comes with it.

Re: Mystery Debris

Posted: Wed Aug 23, 2017 8:41 pm
by paul.jameson
Press the gear off the camshaft, turn it round, then press it back on again. The teeth only wear on one side. Tip courtesy of the late Denys Wilkinson, former UK Membership Secretary.

Re: Mystery Debris

Posted: Thu Aug 24, 2017 1:47 am
by nevhunter
Put a timing mark on the other side for reference when you do that. Put it in the same relation to the keyway as the original side was. Nev

Re: Mystery Debris

Posted: Thu Aug 24, 2017 9:45 pm
by simon.holyfield
Oops. Here's the culprit - exhaust follower...

IMAG0044.jpg


A new set now on the way from Draganfly... Amazing how thin the old one was around the cup.

IMAG0047.jpg


It's a brittle fracture, with heavily discoloured material in the break. It's so thin, the case hardening would have gone right through the material. It's been like that for years.