Misc: Carburettors Poor Running Comet Problem

[Bill Thomas]

If you have points, Always worth a look at,
For clean surface and points coming together flat,
I have an old BTH on my Comet, Years ago , It started OK and a mile up the road ,
Banging and popping, Just dirty points !.

My fault ! Bit lazy, "Was Ok when I last parked it " .

Also my "D" Distributor Twin, Didn't start after a layoff,
Dirty points !, Funny a new set in the bag also had a Some kind of dirt / Growth on them,
Must be CO2 in the air ? .

Now these bikes I have had for many years and never had this problem before ?.

 

[rapide049]

75% of Fuel Problems is Electrical

 

[brian gains]

Cannop - If you're in spitting distance of me , edge of Ashdown Forest/Sussex, you're welcome to have a go with my Comet carb'.

 

[Keith Martin]

We recently had a Meteor with a BTH magneto that would not run properly. Tried different carb settings but nothing changed. Sent Magneto to BTH and had it checked and rebuilt. The bike ran better but still had problems with a misfire at certain speeds. Installed a Lucas magneto and now it runs great.

 

[delboy]

The original posting from Cannop mentions a BTH magneto which he thinks is original, that has had a rewind, I take this to mean a 50's made item, not a modern repro.
delboy.

 

[Robert Watson]

Knowing of course that the modern repro's are a small generator and a CDI box!

 

[erik]

If the bike runs better with the choke down the mixture is to lean.Maybe there is an air leak between the carb and the head and the engine can suck wrong air? I changed to concentric carb .Erik

 

[vibrac]

Brave man Erik!
My inital vote would be the mag especially as its an original BTH

 

[Mark N]

Cannop, are you any closer to resolving the issue? I’m interested as I have a similar issue with my Comet!

 

[Cannop]

Hi Mark, where I'm at now is I've verified the ignition timing again, cleaned the points (to be fair they weren't really dirty), checked the advance/retard weights were operating correctly, cleaned and checked the plug gap, checked the HT lead and cap is in good condition, checked and adjusted the valve clearances, stripped the carburettor and thoroughly cleaned it again, moved the needle clip to position 4 (the bottom one on the needle) and it's running exactly the same as before!

There's something odd going on somewhere but the biggest problem for me is (due various other life issues getting in the way) finding the time to devote to tinkering. I've only managed one afternoon since the last time I posted!