WD 16H Throttle Performance

Needle should be notch 3 measured from the top. Top notch = low needle = lean = pops and spitting and hot.

I would also look again at ignition timing. You want 7/16" BTDC on full advance. Mine is set to 1/2" so I usually run it just slightly turned back, having marked the "7/16" point with paint. Some books have a smaller (retarded) value, and it becomes a hot slug. Do you mean 276 carb? They aren't really fast compared with modern cars and bikes but they should be quite brisk and they would have left most family cars behind them back in the 30's...not all that many horses according to the books, but quite big ones.

... should not be too hot to touch when running although the 16H does suffer from heat transferring when stood after a run. It can make it hard to start as the petrol is vaporising and can need flooding to start.

Your symptoms do sound like weakness in the needle / main jet area - more the former. Top notch doesn't sound right as that is the weakest position.

My WD16H is a lot quicker...but I'd say that 45 mph is closer to 1/3 to half throttle but given its head, it will fly up past 60 mph on full throttle.

There is some confusing information in the factory records about whether the WD models were fitted with compression plates...the WD parts list suggests that they were, but the factory records indicate that the plate reduced compression to 5.9:1 which seems to have been the standard civilian ratio anyway. Regardless, none of us today fit one...

The pre-war Instruction Manual gives ignition timing as 7/32" BTDC...Edgar Franks' post-war book shows 3/8" (12/32") for the 1932 models and there is no mention of any changes and the wartime Maintenance and Instruction Manual shows 7/16" (14/32")...If your engine has been set according to every Norton Instruction Book from the mid thirties to the mid forties then it is probably horribly retarded, as David suggests.

Some people suggest setting at TDC on full retard. I found that mine pinked on full advance if I did that, but it's not far off. I use the 7/16" figure as that's the first one that I found.

This is a pretentious photo as despite setting up a 20mm stroke dial gauge, I'm still using Rizlas for points separation.

Side valves do run hot..oil temperature is high, but once they're up to temperature, they don't seem to get any hotter, regardless of conditions.

Is your carb a new Burlen or NOS parts ? Have you removed the jet block and checked that all drillings are clear ?

When Arthur Bourne tested a WD16H for 'Motor-Cycle', he stated that he took a new one up to 65mph...that really should be possible. They can hold their own at legal speeds on single carriageways.

Blocked drilling are more likely to affect starting and small throttle openings where the engine is running off the pilot circuit. Mid range will be needle and upper range will be timing unless the main jet is wrong...which it isn't. Both are much easier to deal with than jet block issues.

The dial gauge is probably a little exaggerated if you're using fag papers...you'll need one of those fancy electronic devices that Andy Marks sells.

https://www.themagnetoguys.co.uk/magneto-static-timing-light

Hi David,

   Not wishing to teach my grand-mother to suck eggs, but are you aware your magneto will most likely be a tight wire advance ? If the lever friction is not tight enough, these can vibrate back to the retarded position.