Well I seem to have sorted the problem at last.

I had a clear plastic in-line fuel filter fitted, which was nice and clear, however I hadn’t thought about the filter attached to the fuel tap in the tank. Guess which was blocked with rust and other crud from the tank.
Enough petrol was getting through for a potter about and idling but not for actually riding. Hence running weak and very hot as soon as I got out on the road.

I’ve cleaned out the tank, swilled it with phosphoric acid and taken out the fuel tap filter so I can see if any more muck is appearing. The carb got a good clean in the ultrasound bath and at the moment all seems OK…except…the slide is rattling about a bit and is annoyingly noisy.
I will get it re-sleeved sometime soon but I don’t want to leave the old girl without a carb while the original is away. So, does anyone have experience of a 930 concentric on a B33?

I have a box of decent concentric bodies and parts but no idea of jetting for this bike. The standard carb is a 289G/1AT with 11/8 inch choke so the 930 would be a millimeter or so bigger.

If anyone has ideas for a baseline setup, or whether it is feasible, I would be most grateful for suggestions.

Cheers

Pete

email (option): petercomley@web.de

Replicate the general 289 specs and it will run OK...
I find about one turn out from the 'stop' on the primary air screw is best as a baseline setting and set the needle in the middle groove initially...

For the main jet size look up the Monobloc carb spec. for a later B33...Monobloc and Concentrics use the same jet sizes..From memory I think it may be a 260 but check that....

You will find main jet size is not as critical as you may think...Even though the carb is slightly lareger they usually run alright on the standard main jet size...

On an unrelated point...Did you lap the head to barrel joint with fine grinding paste?..And did you take care to tighten the head bolts sequentially and progressively to ensure the head was bolted down 'flat'..?...Ian

email (option): ian@wright52.plus.com

Hi Ian

Thanks for the info! I'll see what I have in the "concentrics box". There's so much left over from 40 years of Triton abuse, and other attempts to demolish Triumph engines, I must be able to cobble something together. You are correct, Monobloc mainjet for B33 is a 260. I'll have to see if I have one left over from the TR6 days (230 standard).

I did lap the head and barrel, almost as much fun as chucking a copper gasket on the BBQ! And, unfortunately, I have a fair bit of experience of tightening the head bolts. First finger tight then round and round the bike with a spanner until I am dizzy. At least I have a hydraulic work bench...I think I would have sold all my bikes by now if I still had to scrabble about on cold garage floors!

Cheers

Pete

email (option): petercomley@web.de