Villiers MK 20 question

Evening all.. have just done up and got going my MK20. Fiddly blighter to start but last night as it ticked away in the garage I looked at the new muffler,the short pepper pot type. It was doing a little bit of popping and looking at the inside pipe it was glowing bright red!!.The popping showed was a blue "explosion/ignition" inside
So ,is that normal? If not what could be the answer why and possible solution?

cheers
Graham
Tokoroa NZ

By no means a mk20 specialist but the first thing I would ckeck is the ignition timing followed by mixture.

Hi Graham,
Definitely re-check timing.
Did you lap in the valves? If so you may need to check / adjust tappet clearance, if not maybe the exhaust valve is leaking un-burnt fuel into the silencer?

Thanks Gents, I did lap the valves ,will recheck all. The spark plug is light brown in saying that the needle valve is very fussy.
Just to be sure in my mind, TDC is the top movement of the piston not the top of the block? And do the points have to be open or just opening?
cheers

Points should be just open when the piston is 3/16" BTDC on the inlet stroke 12thou clearance when points fully open.. TDC is when Piston is at top of stroke.
To save taking the head off about 12deg of crankshaft rotation before TDC is about right.
If you need a manual send me a pm and I can email you a copy

That should have said compression stroke after the inlet

Thank you Ray..I'll take up the offer of the manual...medway48@xtra.co.nz
cheers
Graham
NZ on a sunny day

Hi Graham,
To set needle valve, screw in still it stops, not to hard, then unscrew about two to two and half turns. If tappet adjustment is necessary be careful not to drop the shims under the tappet caps if you remove the caps.

PS Best to not put email address in posts - 'bots may pick it up and start spamming you.

Bots wont spam him as much as all the Lister, Petter and other engine nuts on here will

You are so right Stewart

Thanks Gents . one and all. Amazing what a day makes.... Checked points,tappets etc and decided to rip off the head and start again.
I'm not an amateur when it comes to small motors, motorcycles but i was starting to doubt myself hence all the questions about TDC etc
I had used a DTI and thought I was pretty accurate but in fact the piston was more likely 3/16 past TDC. Must have messed it up when tightening the flywheel.
Redid it rest the carb as and it's running great with no excessive heat in the exhaust and it starts good
Thanks Ray and Woodsman ....as for the bots and germs more work for the delete button

All the best
Graham
NZ

Well done Graham. It's easy to mess up when tightening flywheel nut - done it loads of times