Internal Fire Museum of Power

Would seem my Scott isn't standard, had cox and turner ring to confirm the bore size of my Scott as it seemed a little odd, standard bore size is 73mm, which we both agreed on, but my well warn piston rings I sent were saying other wise, they believed it was closer to 78mm, and on checking it is, I wonder if all Scott SEs are this size or do I have a overbore? The piston seems to be a proper Scott one, just something a bit odd for wear and tear to warrant having nearly a 200thou over bore (100thou of metal from the bore, Not 100% on how its measured)
This puts it up to 341cc, not bad for a engine of 112lbs, Standard is 298cc


Cheers Steve

Doesn't feature in my 1930s piston/ring cats. The Scott M/cs do and none are that dimension.
I will observe that 78mm is 3.07" which is a 3" piston +1/16 o/s or a 3 1/16" piston both with 7.5 thou running clearance (which would be about right).
What is the source for the alleged 73mm standard? I do note that all the M/cs bores are quoted in inches and fractions.

sorry only questions and no answers.
Roland

Hi Roland, no worries, more question can help lead to a answer.

The SE is listed as having the same bore and stroke as the Scott Long Stroke Flying Squirrel, it is also quoted in the sales literial I have here as 73mm by 71.4 stroke, the SE wasn’t introduced until 1930/31

Hopefully the attachment will work. (not brilliant but hopefully you can zoom in a little on it?)

Cheers Steve

Not clear to me whether its 73 or 78. The 1935 (Cos Silver Jubilee) Hepolite catalogue (William Hepworth's personal leather-bound copy Quotes all Scott bores in imperial fractions not mm. The Flying Squirrel and super Squirrel are both shown as 2 15/16" which I make 74.6125mm.
The SE does not appear.

hth
Roland

Hi Roland

73mm on my copy, didnt come out to well in a Scan, but Nick had kindly meassured his and his is about 78mm also, seems rather strange that the sales info say 73mm. unless this is a miss print.

Would also seem that the sales could be a preproduction model as it has a seprate induction tube, where as the production engine is all in one.



Cheers Steve

That's the short-stroke 600 'bike engine (74.6 x 68.25mm) the long-stroke (TT rep etc) is 73.02 x 71.4mm and conventional wisdom has it that the SE should be the same - just that it ain't!

NHH

Is there a convention underlying the quoting of bores defined in Imperial fractions as odd and rounded Metric?

I only ask as it seems very odd to me.

Roland

I only know that Scott literature tends to quote cylinder dims in mm.

As an aside, so does Villiers literature - except for the Mar-Vil!

NHH