Skip to main content
English French German Italian Spanish

Norton 650SS exhaust valve tip wear.

Forums

I wonder if anyone else has experienced their valve adjusters boring a hole in the tops of the exhaust valve stems.

Two years ago my 650SS had a full engine overhaul. Recently, I had a clicking noise from the rocker area.

I checked the valve clearances and the right hand exhaust had excessive clearance. I noticed the valve adjuster had bored a small hole in the valve tip. The left hand exhaust valve had a small indentation. The inlet valve tips are in sound condition.  

I fitted mushroom adjusters that had been sitting in my garage for some time. Today I decided to replace the exhaust valves. Before I put everything back together, I am trying to find out if this is a case of the valve tips not being hardened enough or is there some other cause?

I have heat insulator washers under the exhaust spring cups only.

 

 

Permalink

I've had several Norton twin heads go through my hands in the last few years and have noticed the same thing where the tips of the valve stems are quite indented, so I can only imagine that the valve stem tips aren't hard enough.  Maybe all the indented ones were aftermarket replacements?  Difficult to say.

Anyone have any opinions on fitting 'lash' caps to the tops of the stems?  This may though alter the rocker geometry slightly.

I think it may well be a quality issue with the valve stem tips not being case hardened.

I have read owners fitting Ducati 250 lash caps after machining the valve stem tips that fixed the problem.

Permalink

I've had this issue on quite a few bikes.

Some Japanese,  some British. 

I would leave as is and guess the valve clearance. (Not as hard as you might think) Or if that worried, measure it with a dial indicator. 

Don the bodger.

Permalink

Owning a 650ss bitsa (Non std head) I have the noises, especially at tick over.

I have since covered 2,000 + miles with these noises. Not got any worse.

What is the prospect of long term damage as a result of this?

 

Permalink

For what it is worth. Having observed the same wear but on the intake valve tips of my 750cc motor I swapped out the stock push rods for Commando items and installed lash caps on intake and exhaust. Besides being an easy change over the bonus is that lash caps come in various thicknesses which allows one to dial in the geometry to near perfection. The downside is a bit more top end noise.

Permalink

To Mark Stockslager - Just wondering why you think there is more top end noise with lash caps fitted? I would have thought that it wouldn't make any difference. Also, you say about different lash cap thicknesses allowing you too 'dial' in the rocker geometry - but surely any lash cap is going to increase the length of the valve stem, no matter what thickness? Or are you reducing the length of the valve stems to compensate?

Permalink

The factory fitted longer valves and shorter rods  to   the later  750 motors  , they were obviously unhappy with the geometry , I wonder if the  earlier 650 etc  engines  could be suspect  in that regard.

Bob; My apologies for lack of specifics. I was covering my backside about the noise. Now and again the extra metal to metal contact ( rocker-cap…cap-stem ) is noticeable on some kinds of motors. Dialing in is to factory specifications.

Permalink

When I took our Atlas down I noticed that one of the  adjusters was beginning to break up , With the new adjuster fitted it was clear that the action was very poor.  I then realised that  someone had fitted a later longer valve . With the correct valve fitted the action was perfect . This was a real surprise  as I knew the factory  was unhappy with it  enough to make the changes. On further reflection I realised that the valve seats had sunk over the years  and  this had corrected the action !!.  As the bike was going to be used by Captain sensible  and treated like a Harley I decided to get the chamber and seats reprofiled  to suit.  It has worked fine ,  and illustrates  that  you need to expect  the unexpected with these old  clunkers.

 


Norton Owners Club Website by White-Hot Design