Still having trouble with blue smoke. Checking ring gap which is 8 thou so that seems within tolerances...

The Australian JP pistons seem to have an oil scraper ring visibly thicker than a conventional British made ring such as Hepolite etc. Which represents a difficulty as I hoped to fit different rings to effect a cure or at least help in the diagnoses of my oil problem.

A local chap gave me a Bosch r6 spark plug which has the smaller hex body and thinner insulation. The fact that the central electrode protrudes so much however, gives me reservations about the combustion process.

 

 

Still having problems with oil burning. I have had the head off about six times trying to solve the problem. A standard size piston in a standard sized bored liner must be right. However oil is finding it's way passed the rings. I conclude that the Australian JP pistons need some fettling in the ring grooves.

 

Just as well I took the head and barrel off this time as the small end bush has moved in the conrod.

 

Good photo of Derek Minter standing beside Steve Lancefield the famous Manx Norton tuner.

 

The spark plug on the right is the NGK racing version of the normal plug on the left. the smaller size of the central electrode is quite noticeable.

 

The reverse is true of the plug body as the racing plug has a significantly thicker body.

Very sad to learn that the chap, William Robertson who runs the sprint strip at Crail, Fife, has died suddenly at home aged only 47 as the result of an accident. I hope that it keeps going as it is the only strip in Scotland . These are me last time I was there.

 

There were few artists and illustrators in the 1920's through to the 1950's which had the very remarkable skills of Leslie Carr. This highly evocative picture -in print form- graces my workshop wall and seems to capture the very spirit of motorcycle racing at one period in time. The Norton and the AJS seem like wild monsters battling for the lead.

 

Leslie Carr also did ships and steam trains and I have memories of his work in books as a child. Some towns had tourist posters as well by him. Anyone interested in cars as well as bikes may know that he did a similar style of work of the Le Mans D-Type Jaguar competing about - I think- 1957 and it is with the Glasgow Art Galleries and Museums - but I believe in their reserve stores.

 

 

As a "homage" to my late father I still use his old brass petrol tap, not only because of sentiment but because it is the only one I know never leaks !

 

pins and rings

 

The gudgeon pin ( or wrist pin in the USA) on the right is the type favoured by JP pistons of Australian who supply my pistons with pins and rings. Presumably on a cost basis the hole through the middle is parallel . The original pin has double tapered hole being narrowest in the middle section and therefore lighter.

 

 

Since I have taken the bore back to the standard 71mm new rings are fitted. It is still a misconception among new boys to this game that the rings are made springy to form the gas seal. The fact is that at or approaching Top Dead Centre there has to be just enough ring gap to allow high pressure gas to get behind it and force it out onto the cylinder wall. Old books on engines tend to show illustrations of lapping the horizontal walls of the piston rings to ensure the gap is big enough.

 

The significant engineering task of installing a new cylinder liner is one not to be taken lightly. I entrusted this to Blane Precision Engineering of Killearn not far from me and near where Bob Macintyre planned to have a garage with Alastair King...

 

....note however that not only have the conrod clearance indents been re-machined but that the tiny...perhaps 1.5 mm hole into the cylinder has been re-machined through the new liner fitted...

 

 

...machining off the old spigot and retaining the same height is a job not many would say they could do well.

 

 

All of this incredible expertise is due to one man. Mike Cowie who runs the show.

He is ex Rolls Royce in Hillington - 25 years -and knows everything about Merlin and Griffon engines.

 

I think for certain there must be only a handful of people like Mike in the UK today.