Those OPRV's can be problematic at the best of times, in my experience, but the ball finding its way into the oil gallery must be the fault of the previous person who worked on the engine, surely? Has the inner end of the OPRV body been drilled-out at some time, I wonder?

Allan.

What would you be using it for? If it's for preventing corrosion, it's not great, as has already been mentioned.
Have you seen this?
https://www.bennetts.co.uk/bikesocial/r ... -inhibitor

Hi Johnny,
I don't see any specific references on the Draganfly website, just a general mention of engineering services. I'll phone them and ask.

Thanks, Roger. It looks like all the rockers are beyond the .060" limit so will need building-up and grinding.
The next question is, who in the UK does this kind of work? Does anyone have any experience of having this work carried out?

I'm in the process of building a Mk2 engine from accumulated parts. I have a set of rockers (B-type, with adjuster over the pushrod) and they all show a noticeable wear ridge on the pad which contacts the valve stem end. What is the best option for repairing them? Can they be ground/stoned back to t...

An interesting question! I'm sorry that I can't offer any specific advice on this, but I do wonder that if the play is not acceptable, what can be done about it? Both of my Square Fours have some play in the meshing of the coupling gears, but I just live with it. Someone else will be along with a mo...

Thanks for all the replies.
The general consensus seems to be that it should be ok. Crack testing using dye sounds like a good idea. The pistons are +40 thou, if anyone has one...
I'll have a good think.

The piston came to me in the condition shown, so I don't know what the 'shrapnel' may have looked like.
That's two replies in favour, any against?

Thanks, Roger. There is a question as to how the damage occurred. I don't know if the engine it was in had stopped with a bang, or whether the piston was originally fitted with a piece missing. My concern is, why would someone do that? I follow your logic about it only being a relatively small piece...

Please don't shoot me down in flames, but would it be safe to use this piston in a Square Four? The missing piece is on the main thrust face (where the arrow on the crown points.) The piston had been in use for a very low mileage in another engine and is otherwise sound. Would that amount missing le...