Saturday, 27 October 2012

I note I am holding in the clutch so there must be a car or another bike ahead of me .
One of the problems with buying old spare parts online and hence unseen apart from a picture is that you find stuff that has not been well cared for. Some items I have purchased looked like they had been dredged from the bottom of the sea having been there for decades.
Often you are so desparate for a part you will spend the time salvaging it to be workable again.
An engine is made up of 'big lumps' and all the fasteners and nuts and bolts which hold it all together.
A pet hate is when someone sells you something and does not include the fasteners. Old motorcycles use a huge range of types of thread and it can be difficult to get hold of the correct ones...or even identifying what type they should be.

Friday, 19 October 2012

They say that two heads are better than one and when things can go pear shaped when you are demanding high revs from a half century old engine it is as well to have a spare.

I expect there have been many discussions in the old days about alloy plates versus plain steel engine plates.
These are alloy which I have taken the opportunity to fit as I am re-assembling the engine after a blow up, with a crankcase which is 1956 although my bike is actually a 1960 model. As it will only be used in sprints this is of no moment and all the other bits fit.

After the horror of a small end which 'let go' and the subsequent engine damage during the early 2012 season I am taking no chances and likely fitting a high quality steel or alloy conrod.These are very expensive nowadays but I am also experimenting with alternatives.

The worst feature of towing is when it starts raining and you have to find some place to stop and haul out the covers.
It is difficult to say if desmodromic valve gear would have significantly helped Norton so late in the day when multi-cylinder machines were prevailing.
The combination of  their flat Guzzi type cylinder arrangement combined with the experimental valve gear might have bought some time in certain circumstances but I doubt if for long.

Saturday, 6 October 2012

Pushrod tubes of this type are fairly easy to make . The one on the right is original Norton. The left one is fabricated from a length of alloy tube belled with a ball pein hammer. the top part is made on a small lathe.
When  the small end of a conrod decides to break it can release hell !
Fortunately valves are still available but I find prices can vary .
On the Norton single both valves are the same which helps as the exhaust usually goes first.
Note I do not have a high comp piston. I follow the dictum of  that master P.E Irving.
In his bible " Tuning for Speed" he states..." and it must always be remembered that it is not the actual measured compression ratio which counts, but the pressure of the gas at the end of the compression stroke".
This simple fact is something many people forget.