When you read this heading you doubtless think we should provide a lot of information, and so we will, if you send along your enquiry stating the model and also, the particular class of work for which it is to be used. Has it not struck you that different engines require different treatment in the way of tuning ? Let us hasten to assure you that such is the case. Many suggested alterations are supposed to add "miles" on the performance of your machine, so they will but not M.P.H. or M.P.G., they will actually be miles of slower touring, lower cruising speed, and more petrol to be poured into the tank !
Some of the suggestions are really very good, so they should be, they are those issued by us in reply to enquiries but, if intended to assist in the tuning of a "Super Model" they are not much good in view of the fact that they were issued to cover the early Replica engines. Yes, we agree the cylinder will look like a Replica, but you must take into consideration such things as Port Timing, Compression Ratio, Type of Piston etc. The letter shown earlier under the Heading of REPAIRS is connected with just such a case of "Super Tuning".
The point to remember is,- by indiscriminate alteration you may absolutely ruin the performance of the engine at small throttle openings. Acceleration may take "yards" more, and the only advantage be a mile or two on the actual maximum, WHEN YOU GET IT, therefore, be advised by the makers of you motorcycle, they are just as keen to assist in the matter of performance, as you are to obtain same. Here are a few tips for the owners of Flyer Models (Engines FZ and FY), assuming the same to be in good condition, preliminary attention, as outlined in the "Book of the Scott" given.
ENGINE.- Clear all carbon, polish rods, cranks , piston heads and combustion head, remove all carbon from plug ferrule threads. Polish all ports, use a dead smooth file or scraper, do not alter the contour except in the case of ports around the cylinder spigots, these can be "squared" and the bridges streamlined. Clear any roughness from the crankcase inlet port and polish same. Enlarge the hole in packing to allow free flow from carburetter. Carefully "ease" any high spots from pistons, check skirt clearance (when new .006 in.). special attention to deflectors, the pistons should be quite clear of the cylinder wall at these points. Piston rings should be any easy fit, gaps .008 in., rods perfectly "true."
Shorten piston skirt by 1/16th in. on inlet side to give earlier opening and increased R.P.M. Test half compression valves and correct the lightest leakage. When re assembling, take care to register all packings. Do not fit transfer port gauzes. Thoroughly clean exhaust system and use GENUINE SCOTT pipe, bend and size of which has been determined by extensive test.
CARBURETTER.- Three jet Binks Amal type-Jets Pilot 35. Centre 50, Main 120. or, when using P.M.S. 2 Pilot 50, Centre 70, Main 170 or 180. Amal. needle type, (Standard)-Racing Jet 180, with P.M.S. 2-Jet size 200. Amal. type 29/005. with 1/32 in. choke-Jet 200 with P.M.S. 2-Jet size 325.
NORMAL FUEL.- Pure Benzol and Aviation Petrol in equal quantities.
MAGNETO TIMING.- as standard see "Book of the Scott."
PLUGS.- For racing, K.L.G. 583 or 346. Lodge BR. 53, for fast touring K.L.G.-KS5.
LUBRICATI0N.- For gear, use same quality as for touring. For engine Castrol R. Set feeds to 20 drops per minute, oil level in crankase to be slightly lower than top of well. When cylinder wall oiling is not fitted add a little Castrol XXL to petrol, about ¼-pint per gallon.
GEAR RATIOS.- These are best found by test, suggestions are :- with 498cc. engine - 18 tooth, and with 596cc. engine - 20 tooth counter-shaft sprocket.
GENERAL.- careful alignment and adjustment of chains, also Lubrication. Avoid over-tightening of wheel hearings, do not over-fill with grease and by so doing impair the efficiency of brakes. Adjust brakes accurately, see they do not "rub" when "off." Find the most suitable tyre pressures by careful experiment. Regular check of all nuts and bolts, particular attention to such vital parts as Brake torque anchor bolts, steering damper fixing, gear operation rods and parts. Space will not permit our detailing all points, and "hints" on other types, but your enquiry will receive every attention.
A FEW FINAL REMARKS.
DO NOT ALTER YOUR ENGINE BEFORE HAVING THE MAKERS' ADVICE. LOOK FOR THE "SCOTT" SIGN AND OBTAIN GENUINE REPLACEMENTS. HAVE YOUR REPAIRS EXECUTED BY ACCREDITED REPAIRERS. ALWAYS QUOTE THE ENGINE NUMBER AND SERIAL LETTERS.
And lastly, make every use of this department, we are,
At your service,
The Scott Motorcycle Company
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