“Harley-Davidson” name for reference purposes only. Not affiliated with Harley-Davidson Motor Co.
This is the complete
IBRARY booklet on the Linkert (L&L) Model “M” brass carburetor, as used on all Harley-Davidson
motorcycles 1933-56 (and some until 1964). This includes: Knucklehead 61” & 74” 1936-47; Panhead 61” & 74” 1948-64; VL Flathead 74” & 80” 1930-36; 45” Flathead solo, military & Servi-Car 1933-58; K, KH & KR Models 1952-65; U-Series Flathead 74” & 80” 1937-48 (sorry, not Sportsters).
Although I’ve written this primarily for H-D models, the information is generally applicable to Indian Chief 74” & 80”, Scout 45”, Junior Scout 30.50”, Motoplane, 841 & 741 Military, and Four Cylinder.
If you own (or plan to own) one of these great classics, they all came factory-equipped with a Linkert carburetor! For best performance, you should learn all you can about the Linkert carburetor, and how to get the best results from yours. This is not a repair manual, but begins where they leave off, and 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 this
useful to identify what parts you need, detect wear and damage, mis-matched parts, etc. - take it along to the next swap meet.
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 factory literature and is not available anywhere else, and not included in any of my other books; click here for other related titles: .
I guarantee that you’ll find information in this booklet you’ve never seen before, and that will help you plan and complete your Linkert 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 have invested in the carburetor - plan more intelligently, and get better results.
This booklet was just revised in January 2011. It’ stapled in paperback to save printing costs, includes all the following subjects in 59 pages (over 45,000 words), over 30 black & white illustrations & diagrams plus 31 data tables:
How the Linkert Works; an in-depth examination of how the different circuits operate, exactly what each component does, how to interchange parts and make adjustments. This is the only place you’ll see this
information (much more detail than the factory service bulletins).
Linkert Speed Tuning; any Linkert carburetor can be adapted to another motor, or fine-tuned for better performance with these simple modifications and adjustments. This chapter explains how to make high-performance modifications, adapt the larger 4-bolt 1½” model Linkert to the 45 or U-Series, improve throttle response, make adjustments for hot cams, more air-flow, includes formulas, list of tools & supplies, and a worksheet for you to record your progress. No complex machining is required.
Linkert Carb ID; gives the body casting size, serial number, throttle disc (butterfly) & venturi size, and application for more than 50 Linkert models (including knucklehead, panhead, 45, UL, K & KH Models, Indian, etc.).
Linkert Carburetor Selection; can’t find the original Linkert carburetor for your motor, or don’t want to use it? This chapter explores possible alternate choices, depending on your motor type, size, intake manifold, cam timing, etc.
Linkert MR-5; can’t find (or afford) a big factory racing Linkert for your hot 45? Here’s how to make a Linkert “MR” replica for your WR or racing WL from the more easily available M-74B.
Dual intake manifold fabrication; how to convert your engine to dual Linkert carburetors, size selection, what parts are needed for your current carburetor, how to make your own individual manifolds from common materials.
Tuned length intake manifolds; how to make calculations for more power, including 5 Tables of pre-set manifold lengths based on cam duration, RPM, etc.
The Linkert Main Nozzle; what does it do? Why are there so many different Linkert main nozzles? Which one is best? Can the Linkert nozzle be modified?
What's a “booster venturi”; what does it do? Will it help your Linkert?
Tunnel-ram intake manifold; more power for Linkert single-carburetor racers with theory, calculations and dimensions, including illustrations and Tables of pre-set data.
Tuned “Helmholtz” resonator; add an air box for power, discusses theory, calculation and dimensions, including Tables of pre-set data.
New intake port fabrication; how to convert your side-valve cylinders or OHV 1936-47 knucklehead or 1948-65 panhead heads to dual port, alignment, size, &c. with illustrations.
Dual 1½” Linkerts; setting up a big twin dual-carburetor Linkert installation, using the common 4-bolt M-74B.
Dual 1¼” Linkerts; setting up a 45 dual-carburetor Linkert installation, using the common 3-bolt M-51 or M344. Indian Chief & Scout owners: make your own “Altoona” motor!
Linkert MR-8; making a high-flowing, adjustable “MR” replica for your knucklehead or panhead OHV stroker from an M-74B for maximum performance with old-time appearance.
Linkert MR-9; making a high-flowing, adjustable 1¼” carburetor for your pre-1940 H-D racer or Indian Chief or Scout from the common Linkert M-51 or M344, etc. for maximum legal performance where later & larger carburetors are not permitted.
Linkert Air Cleaner; how to modify & improve the standard Linkert “bell” air cleaner for more air flow, while retaining stock appearance.
Velocity stacks and ram tubes; how they work, which ones are best.
Beck Replacement Linkert Carburetors; decoding the numbers.
Converting the Linkert to Alcohol; methanol, ethanol, etc. effects on jetting, ratios, safety, etc.
I’ve also written booklets for British motorcycles on Amal Concentric carburetor tuning: , Amal Monobloc carburetor tuning: and Mikuni VM carburetor tuning: .
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 Linkert carburetors. 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 carburetor. 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.
New: get this booklet plus “45 Performance” or “80 Performance”at reduced price, click here for details: .
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