setting up tappets on an NH

[Terry.C.]

Hi all you NH experts out there.
Can some one please tell me how you set the Tappets on an NH Motor. I know the dimensions but there seems no way of getting a feeler gauge into the rocker cover apperture.
Regars Terry

[Simon.Gardiner]

Terry - I think you've got a '53 bike with an iron head, for my '53 the settings were nil (inlet) and 2 thou (exhaust).
For the inlet, I'd set it by feel - no clearance to feel but able to slide the rocker arm across very easily.
For the exhaust, just able to feel a bit of clearance. (You need to make sure the exhaust lifter is clear of the rocker arm, and it'll only be a very thin feeler gauge so it probably will go in with a bit of fiddling?)
However, if this is a first-time start after a rebuild (ie new rocker box gaskets) you need to allow quite a bit of extra clearance, so set the tappets 'clacky' - new rocker box gaskets 'give' a lot in the first few hundred miles and close up the tappet clearance massively - although it's easy to spot this as all the compression disappears....

Hope that helps

SG

[Terry.C.]

Thanks for the reply Simon. Very useful information especially about the de-compessor.
Regards
T

[nevhunter]

It's all you need to Know but take note of the need to tighten the rocker box bolts a few times with the Proper thick gaskets and that alters the valve clearance a lot. (closes it up). A thinner gaskets or Pocketed Valves upset the Geometry and cause excessive valve guide wear When the valve is 1/2 open the angle between the rocker arm contact point and the rocker Pivot centre and the Valve axis should be 90 degrees. Nev