Below a snippet from one of the e news letters:
Q) If I was to install your high flow transfer ports on my two speeder without any other modifications (well carb setting perhaps), would it make any difference or would it just be a waste of money?
A) A waste of time I think. Main problem with two-speeder as regards efficiency, is the side mounted carb. It is necessary to starve the LH inlet with a deflector to balance the lower volume input to the RH side. You could consider balancing them with a “T” branch inlet, but then it would not be “Original”
Q) Could you explain why the mixture on my 2-speered is not equally divided over both barrels?
A) Gas / air and water all react in the same way. If you want to learn about gas flow, study water flow in brooks / rivers etc. e.g. a brook going round a RH bend.
Imagine this as being similar to the inlet tract on a Two Speed Scott. Water will be faster on outside of bend i.e. on the LH side. It will act like when you tie a weight to a string and swing it in a circle.
Now look at the speed of the water current on the RH side of the bend, i.e. the inside radius. Water is slower and the depth is less. If the bend finishes and the stream continues in a straight line, then the water entering the straight section will have much more speed and energy on the LH side. If you were now to divide the stream into two channels like the inlet of a Scott Super, then about 66% of the water flow will go down the LH channel and about 33% will go down the RH channel. This ratio changes with speed and inertia, so the balance becomes progressively worse as revs rise.
Scott’s answer to this was to fit a metal deflector plate to restrict the flow on the LH until it was more balanced to the flow on the RH side.
This is why I remove some inlet pillars in the central area of greatest flow.
If you want to retain the original Two Speed inlet tract, but try and make the induction more balanced between the cylinders, you could remove the majority of the centre two bridge pillars on the RH bore, so it deals more efficiently with the lesser flow that is delivered to it.
Ever since I have emailed with Roger about this (it were my questions in the newsletter) I have been thinking about making a Y shaped twin carb inlet manifold for my two speeder. To balance out the uneven filling of the cylinders but also for fun as I have never seen a twin carbed two speeder before.
But re reading the e newsletter I realised Roger was talking about the later type of super engine with the three stud manifold. My bike has the earlier type manifold in which the gas flow is quite different. See below (I have no other 3D CAD programm than the virtual Lego designer but I think you will get the idea):
In real the twin carb manifold I had in mind would be more Y shaped than T shaped for better flow.
So my questions:
– does this older type of engine also have a deflector plate fitted? I cannot quite figure out the gas flow but in my opinion this would not be as unequal as in Rogers example? Or maybe it still is due to the first 90 degree corner it has to take?
– would a second carb be any good?
– does anyone know of another twin carb two speeder?
Sorry to throw a red herring into your postings, Erik, but on the subject of inlet manifolds does anyone have knowledge/ a drawing/ photograph of the one-piece inlet and transfer manifold marketed by the Wardonia Motor Engineering Co of Bradford? “It bolted on, in place of the exisiting transfer port covers”
See Jeff Clew’s book of the Scott p111.