Musing on my questions from yesterday I have thought through the engine side of BRP.
Going back a year now the number 1 plug was blown out of the engine whilst returning from a BCC autotest. Further investigation implied that the thread in the cylinder head for number 1 plug was suspect which would mean having a helicoil fitted.
Now we are in the "whilst you're at it" realm.
Having a helicoil fitted would mean removing the cylinder head and whilst it's off then it would make sense to replace the timing chain and tensioner whilst I could also fitt a vernier sprocket which would enable finer tuning of the timing.
Meanwhile, if I shimmed the valve clearances I would optimise performance and quieten the whole thing down.
Result - a more reliable fully sorted cylinder head and valve train etc.
But then I thought "hold on, the plug hasn't blown out again so maybe it was just loose". The other thing is, the engine hasn't been overheating and the oil pressure is fine. Removing the cylinder head could would obviously disturb the head/block seal and that's not something I am keen on doing if all is well otherwise.
So? Simple really - take the rocker cover off and investigate that "plug hole".
That "plug hole" seems fine to me - it looks OK when a light is shone down it and there is no difference in feel between number 1 and number 2 when I tried removing and replacing plugs.
So now I am moving from "whilst you're at it territory" to "leave well alone you idiot/if it ain't broke, don't fix it".
Next step is to shim the valve clearances and then put it back together with the aim of leaving well alone. Having said that, maybe I am doing something wrong but the valve/tappet clearances seem way too tight.
Further investigation next week I reckon.