Roger Gwynn wrote: Thu May 14, 2026 11:27 am I would suggest honing the bore by half a thou, (.0005"). .005" is the bottom limit for clearance and I would aim for the median of .006". My VA used to seize if it was thrashed, took half a thou out and it has never misbehaved again, well not by seizing anyway.

Thank you, Roger.

Currently have Hepolite 4173 (86.4mm) but have been suffering with seizures (the bike, not me).
Done 100 miles so far. Bike always starts after a few minutes, not sure what my options are here?
There is 5 thou clearance top and bottom, the rings are free.

nevhunter wrote: Fri May 01, 2026 1:05 am What Bike is it, may I ask.? Nev

500 Red Hunter (now added to my signature )

Yes, in the end I decided to fit a spade end and thumb nut on the plug - looks right for a 1933 bike

answered my own question:

None of the NGK plugs caps fit the Champion D9’s.

But these do:
Pattern Spark Plug Cap R90 Black Water Resistant Rubber Lodge No Resistor
https://www.gsparkplug.com/1x-pattern-s ... istor.html

Have just bought Champion D9 spark plug - but the current plug cap (LB05EH) doesn't fit as the spark plug is wider than the old one.
I could use a spade end fitting but would like to know if there's a plug cap that fits?

Solved.
The two spindles are different sizes (OHV type on top, Side valve type below) So I had a bush made up: and fitted:

Is the spindle this one:
https://draganfly.co.uk/shop/63176/exhaust-lifter-spindle/#335-30exhaust-lifter-spindle/category_pathway-2

PXL_20260415_101521969.jpg PXL_20260415_101457724.jpg
and this will need attention as well:
PXL_20260415_095746757-EDIT.jpg
but I'm not sure how easy to remove ...

mine looks like this...

Turns out the mechanism (lifter shaft) is badly worn so I have put a wanted post on the forum.