Am always tempted by some of the more exotic racing fuels but am happy for the moment to stick with normal pump fuel. Inspite of all the worries about using unleaded all seems well with the valve seats in that regard.

 

Winter work is something I feel you have to stick at as if you leave off too long you forget what bits you were working on !

 

managed after very many years to get hold of a copy of that wonderful book by Philip H Smith " The High Speed two-stroke petrol engine" . As a young man I was enthralled by it when borrowed from my local library and since many of my generation started out on two strokes I am certain others retain a soft spot for them. This page above illustrates a range of piston crowns and for good measure Smith included a Manx Norton one on the bottom right corner. 

 

 

 

I was significantly lighter in my younger days and so the scale of those lightweight machines was an added attraction. The popularity of the disc intake valve provided the answer to a lot of the issues of timing racers using the two stroke principle. What a pity that emission laws have all but made them disappear. There is certainly a need to redevelop the two-stroke in harmony with current emission thinking and technology.

 

This is a good drift for helping remove a big end . I made it from a piece of old steel scaffolding tube off-cut which happened to be on the edge of a pavement I was walking along near abuilding site ! 

 

Inevitably a new big end is expensive as it is made of very high quality steel and rollers. This one cost me £130; but for single cylinder Norton's I have seen the same bearing priced at £200 and I don't mean for a Manx model which is very different type of big end bearing.

crank at work !

 

Managed to get hold of a very good condition standard conrod.

It is getting more difficult to source stuff like this as some things people sell are very poor having been left outside for years. 

 

Testing the trueness of the drive side flywheel. For some reason the timing side wheel seems perfectly straight but I can detect a slight high spot on the drive side wheel. The main concern is if it is caused by a bend in the main shaft.

 

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.