Norton 16h Problems!!!

[gary0003]

I have just restored a 1937 16h but can't get it to fire!  The ignition seems fine (good spark) but the plug does not get wet at all. petrol is definately coming through to the carb but not being sucked into the chamber. it gets spat out of the mouth of the carb though. I am not totally confident that I have got the valve timing correct - could that likely be the problem? 

is it possible to set the cam wheels by counting the number of teeth from a given point when the piston is in a certain position (ie TDC) as I seem to be having great difficulty correctly setting the Timing?

As a rough guide - how many turns out should the mixture screw be set please? 276/1be carb.

Also the circular cap which hold the spring in the timing chest continually dribbles oil through its centre when kicking over the bike - Is it supposed to have a small hole in its centre please?

Thanks for your help

Gary.

[welbike]

Where's Ron when you need him? Anyway, I will try to answer some questions,

Valve timing could indeed be incorrect, easiest to check is to take the cylinder head off, valves should be rocking at TDC, when not on the compression cycle.

Mixture screw starting point is 1,5 turns out from completely closed.

There should not be a small hole in the cap in the timing chest, maybe it has worn through somehow?

Cheers,

Lex

 

[Ron]

I missed this one!

Are your cams not marked with the meshing dots and dashes? It should look like the illustration. It is possible the work it out by counting the teeth. But best if you can start by finding the dash on the pinion. 

Also to note with these when setting the ignition timing , is that the points revolve in an anti clock rotation. 

 

Ron

Edited November 3, 2022 by Ron

[gary0003]

Hi guys, thanks for your help. I think I have resolved the issues. There are no marks on the cams, but the Norton Owners club provided me with the answer for the valve timing:

Turn the engine to top dead centre, if you have the mag timed up make sure you are on the stroke with the points closed. Turn the engine forward so the piston moves down a 1/4 inch and fit the exhaust cam so it has just closed, checking the rotation as above. Next, turn the engine back over TDC so the piston is coming up 1/4 inch from the top and set the inlet cam so it is just about to open, again checking the correct cam rotation.

   You might not be able to get the positions dead accurate but you should be fairly close with a fraction more measurement rather than less. The early engines have a 3 key-way half-time pinion with the slots in different attitudes to the teeth and this allows finer setting. 

I have sealed the cap (no more dribbling!) and heavily greased the valve stems which seems to be helping the engine run cooler (doesn't seem to be getting too hot? The bike now starts easily and runs cleanly and cooler!

Thanks again for your help - what a great couple of clubs!

Gary

[Ron]

Well done Gary. The rocking at TDC that Lex mentioned is a kind of what they call "Valve overlap" It's were the exhaust valve is still closing as the inlet valve is starting to open. ie The outgoing exhaust helps draw in the new fuel charge. 

The BSA M20 has a more pronounced "overlap" and there is a special system for adjusting the tappets on those. 

But back to the 16H. I found this YouTube video which shows it, by a bloke who had the same problem.  Ron