IBRARY’s comprehensive booklet on obtaining speed & performance from your Harley-Davidson 74 & 80” flathead 1937-48, including model letters U, UL, UH, ULH, UA, UMG, etc. It’s the original, best, and most complete idea source for speed & power from your UL (first published in 1984). It should be your first step to modifying your own motor. These instructions get immediate results, and are easy to follow; no welding or expensive & complex machine work is needed.
Your “obsolete” 80” side-valve is capable of surprising speed & power, without loss of original appearance or reliability. Over 30 years of research and experience has gone into this booklet. It’s the best do-it-yourself literature you can buy to get the most from your Harley-Davidson UL. Before making any decisions about modifying (or even rebuilding) your motor, get the most help available, and do it right the first time. This booklet is not a repair manual, but goes far beyond into fine tuning, improvements and modernization. Use it with your service manual for best results. Not an expert mechanic? You’ll still find many improvements you can make yourself with common hand tools.
IBRARY is the original
source of side-valve performance (since 1971). Click here for a brief bio on the author: . This information is not reprinted from other articles, magazines, or H-D factory literature
and is not available anywhere else.
Stuff & nonsense; some common myths & legends about motors.
I guarantee that you’ll find information in this booklet you’ve never seen before, and that will help you plan and complete your 80 project.
Consider this: if this booklet saves you from making even a single mistake or bad purchase, or gives you one new idea, doesn’t that make this purchase worth while? The price is a small fraction of what you will invest in the motor - plan more intelligently, and get better results.
Contents are newly revised (March 2011) and expanded to almost 50,000 words, stapled in paperback to save you printing costs, including many black & white illustrations, diagrams and charts.
Stroker flywheels; details on installing long-stroke flywheels using Truett & Osborn (or S&S) flywheels, selecting components, where clearancing is
necessary, calculating skirt lengths, piston compression distances, ideas on adapting commercially-available pistons, much more. I wrote the original Easyriders” magazine article on this subject in 1978!
Relieving; a general discussion of relieving the cylinders & heads for better flow and more effective combustion, plus detailed specific instructions to help you plan & complete reliefs on your UL for better performance.
Timing the cams; how to fine-tune cams to change their effect.
Quench and squish; what do they mean, effects, measurements.
Compression ratio; calculations, measurements, suggestions.
Porting; instructions for improving the UL’s breathing capacity, both intake and exhaust, from the valve seats to the port opening, for all cylinders 1936-48.
Dual-port cylinders; a guide to modifying your cylinders for new intake ports, for better flow
using 2 carbs, with tuning tips, dimensions, diagrams, etc (machine work required).
Dual intake manifolds; a guide to fabricating new manifolds (using the original port position),
for better flow using 2 carbs, with tuning tips, dimensions, diagrams, etc.
Hot parts; the only detailed guide to speed equipment for the U-Series motors, gives part #s, data on original use, measurements, interchanges between models, how to identify parts such as heads, manifolds, cylinders, rods, crank-pins, cams, & cam covers by casting numbers, dimensions, much more.
High-speed valve gear; detailed instructions: how to plan, modify & install high-RPM springs,
tappets, collars, etc. with charts, diagrams, dimensions, formulas, & tables; parts needed.
Exhaust system; design & build a better 2-1 exhaust, choose mufflers, tuned lengths.
Oil system modifications; including breather timing, increasing pump efficiency.
Big twin trike; some hints on making a 3-wheeler with a big twin power train, selecting motor components, gearing choices, major differences between models of Servi-Car frames, rear axles, forks, etc.
Racing specs; clearances, end-play, settings, dimensions, etc. for high-performance engine
assembly of 1937-48 motors.
Bore & stroke chart; gives engine size for all bore oversizes & stroker flywheels.
Big twin sprocket ratio chart; gives ratio and speed for all motor & transmission sprockets.
Big twin transmission ratio charts; gives exact ratios for all 1936-* 4-speed gearsets, factory and aftermarket, with RPM recovery proportions, which gears mate with what in the transmission, shows how ratios are calculated, as well as tooth counts etc.
Service tips; many useful shop short-cuts and hints.
Good numbers?; some ideas on decoding VIN numbers, detecting alterations etc.
Spark advance charts for most stroke lengths.
Harley-Davidson special thread size chart.
Please note: this is not a coffee table book, it is intended to be a research tool for those who seriously want to improve their UL engines. It is not a repair manual. If your bike won’t start, float bowl leaks, spark plugs foul, &c. my booklet will not help you. It does not contain information on tune-ups, or explain how to remove, disassemble, clean or restore the bike. If you do not already have this information do not buy this booklet. If your engine is stock and you’re pleased with how it runs now, this booklet is not going to be of much use, although you might find it interesting.
“80 Performance” does not include any 45, Linkert, Mikuni, 45 Magnum or British transmission information, please order these separately: .
New: get this booklet plus “The Linkert Book” at reduced price, click here: .
New: get this booklet plus “45 Performance” at reduced price, click here: .
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