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Blog
Welcome to the Kingpin Components blog, where I share my experiences of riding, restoring and maintaining classic motorcycles, alongside running Kingpin Components. Along with technical articles and practical workshop insights, this is a place to explore classic bikes as they are actually used — not as museum pieces, but as machines to ride, tinker with and enjoy. Long before Kingpin Components existed, I was a motorcyclist first, and that’s the perspective this blog is written from.
Here you'll find technical articles alongside posts about my own bikes, restoration projects, workshop jobs, rides, rallies and events, together with honest opinions, lessons learned and practical advice for using classic motorcycles on today's roads. There will naturally be some overlap with the work I do through Kingpin Components — parts I’m developing, interesting customer projects and problems that needed solving — but this isn’t a sales pitch. It’s simply a place for me to document the experiences that come from classic motorcycles being both my hobby and my business.
How to Fit an Andre Steering Damper
A complete guide to selecting, assembling and fitting an Andre steering damper. Covers both 2-plate and 4-plate dampers with detailed photographs and practical fitting advice from the workshop.
Andy Marks
Jul 234 min read
AMAL Type 76 Carburettor Fault Finding and Repairs
When my Norton CS1 started fouling plugs and smoking badly after cylinder head work, I assumed the carburettor would need minor adjustment. The real fault turned out to be far more interesting and had probably been hiding in plain sight for years.
Andy Marks
Jun 243 min read
How to Check and Adjust Fuel Level on AMAL Pre-Monobloc Carburettors
This guide explains how to check the fuel height using a simple sight glass, identify common faults and make any adjustments required.
Andy Marks
Jun 223 min read
Norton Dolls Head and Upright Gearbox Shells - Repairs and Modifications
A common problem with Norton Dolls Head and upright gearboxes is cracking or breaking around the upper mounting ears. This guide covers our preferred repair method, including modifying the top mounting arrangement, repairing worn pivots and machining new mounting components to prevent the problem returning. Why Norton Gearbox Mounting Ears Break Cracked or broken mounts are usually caused after the gearbox has come loose and been allowed to rattle. This wears the bottom pivot
Andy Marks
May 184 min read
Oil Tap with Cutout Switch - FAQ
This page answers the most common questions about our oil tap with cutout switch, designed to prevent wet sumping on classic motorcycles. It covers how the tap works, how to fit and wire it, and what you need to install one on your bike. How does the Oil Tap with Cutout Switch work? Our Oil Tap with Cutout Switch can be connected to bikes with magneto or coil ignition. They ensure that, if the oil tap is 'off', the switch will stop any sparks and the engine cannot be started
Andy Marks
Apr 134 min read
Wet Sumping - Why It Happens and How to Stop It
Wet sumping is a common issue on classic motorcycles where engine oil drains from the oil tank into the sump while the engine is not running. This guide explains why it happens, how different types of oil pumps affect it, and the practical solutions available to prevent it, from maintenance and riding habits to anti wet sumping valves and oil line taps. What Is Wet Sumping and Why Do Classic Motorcycles Do It? Wet sumping is when engine oil slowly drains from the oil tank int
Andy Marks
Mar 235 min read
How to Convert Road Speed to Engine RPM
This guide explains how to convert road speed into engine RPM using the gearing and rear wheel size of your motorcycle. By using the number of teeth on the engine, clutch, gearbox and rear sprockets together with the rear wheel diameter, you can convert miles per hour into rear wheel speed and calculate the corresponding engine RPM. A downloadable spreadsheet is also included to automate the calculation. Using Motorcycle Gearing to Calculate Engine RPM This is very useful w
Andy Marks
Mar 172 min read
How to Convert Engine RPM to Road Speed
This guide explains how to convert engine RPM into road speed using the gearing and rear wheel size of your motorcycle. By using the number of teeth on the engine, clutch, gearbox and rear sprockets together with the wheel diameter, you can calculate rear wheel speed and convert it into miles per hour. The article also includes a spreadsheet tool that performs the calculation automatically. If you want to perform the opposite calculation, see our guide on converting road spee
Andy Marks
Mar 172 min read
OHV Norton Piston Options
This guide looks at the piston options available when increasing the compression ratio of an OHV Norton engine. Standard ES2 pistons, modified 16H pistons, BSA B40 scrambles pistons and custom piston designs are compared, along with the advantages, drawbacks and machining work required to make each option work. Standard Norton ES2 Piston As you'd probably expect, standard ES2 pistons offer the simplest option during an engine overhaul as they fit straight into the engine. The
Andy Marks
Mar 174 min read
Norton SOHC Cambox Tunnel Repair
This guide explains how to repair the damaged camshaft tunnel in a Norton SOHC cambox, a common issue on these engines. The article shows the full machining process required to restore the tunnel, including boring the cambox, turning a replacement tunnel in the lathe, drilling oil drain holes and reassembling the cambox correctly. The Common Problem with Norton SOHC Tunnels One of the most common problems with the Norton SOHC cambox is damage to the tunnel that the camshafts
Andy Marks
Mar 174 min read
Velocette M Series Cam Data
From the first MOV to the last Thruxton the M series Velocettes all used the same basic design for their cams. The profiles varied but all are interchangeable from one model to another. Below is a table showing the timing figures for each cam along with the checking and running clearances and finally a note on what they were originally fitted to. Return to Velocette Technical Guides or Technical
Andy Marks
Mar 171 min read
Pre-war Norton Engine Numbers
Pre-war Nortons did not have consecutive or matching engine and frame numbers. The only way to properly identify and date these engine and frames is to contact someone with access to the factory records. The Norton Owners Club has them. Pre-war engines can be dated from the number. The table bellow shows the range of engine numbers from 1923 through until 1939. 350cc engines used a separate range of numbers as follows: From 1929-1936 the ranged from 1000-6200 From 1937-
Andy Marks
Mar 161 min read
Post-war Norton Engine and Frame Numbers
Post-war Nortons can be easily dated and identified from the prefix. The letter denotes the year and the number denotes the model. The same numbering system was used on both engine and frame, and they should match on an original machine. The two tables below show the pre Commando models up to 1960. Return to Norton Technical Guides or Technical
Andy Marks
Mar 161 min read
OHV Norton Cams
Post 1948 OHV Norton valve timing is very ‘soft’. If you are trying to get the best out of your engine it is one area that significant gains can be found. You can get a bike to go well with standard cams but it is important that the timing is spot on - don’t rely on the dots! You can check your valve timing against the figures shown on this page. If you would like a little more performance from your bike - read on to see what your options are. Irving’s Recommendation This dia
Andy Marks
Mar 162 min read
Norton Engine Data
The table below shows data for Norton singles from 1928 to 1955. A couple of notes: Valve and ignition timing given in inches for all models except the 30 and 40, these are given in degrees. Notation for valve timing as follows: IO - Inlet Opening (Before TDC) EC - Exhaust Closing (After TDC) When tappet clearances are given as ‘zero’ pushrods should be free to rotate with no perceptible up and down movement. Tappet clearances are running clearances and taken when cold. Cle
Andy Marks
Mar 161 min read
Quick Restoration Tips
On this page you will find a selection of technical hints and tips that we think you may find useful but don't justify a page of their own. If you can think of anything that would make a good addition, why not Contact Us. Tip 1 On a Norton gearbox replace drive side lay-shaft bearing, no. 6203 (40mmx 17mmx12mm), with a NJ203 roller. Tip 2 Norton primary chains get tighter as everything warms up – aim for at least 1’’ up and down movement when cold. Tip 3 Valve Timing on OHV N
Andy Marks
Mar 163 min read
How to Identify Unified Thread Series
Unified Thread Series (UTS) is a set of thread forms most commonly used in North America. As you would expect most American bikes use these threads. Influenced by the number of bikes being exported in the 1960’s a lot of British manufacturers started using them as well. Unified Thread Series Form UTS nuts, bolts and screws all use the same thread form as shown here. It is the same 60 degree thread angle as ISO Metric threads but uses a number of Teeth Per Inch (TPI) rather th
Andy Marks
Mar 131 min read
How to Identify British Standard Threads
British motorcycles used several forms of threads and it can get a bit confusing trying to identify what you have got. But if you have a vernier calliper and a thread gauge it doesn’t need to hold you up. Here are the most common ones used on most British bikes before about 1960 when pressure from the export market caused some manufacturers to start using American standards. British Standard Whitworth (BSW) This is the coarsest thread you are likely to find on a British bike
Andy Marks
Mar 132 min read
Converting Crank Rotation to Piston Drop
Some manuals show how to time an engine using degrees of rotation at the crankshaft, some show how to do it measuring piston drop down the bore. Few, if any, give figures for both. If your manual gives a number of degrees from top dead centre (TDC) but you would prefer to use piston drop as a distance before TCD - this page will show you how to convert. If you don’t fancy doing the maths yourself just skip to the bottom and download our spreadsheet that will work it all out f
Andy Marks
Mar 122 min read
Converting Piston Drop to Crank Rotation
Many workshop manuals specify engine timing as piston drop measured down the bore before top dead centre (BTDC), while others use degrees of crankshaft rotation measured with a degree disc. Few manuals provide figures in both formats, which can make it difficult to use the timing method you prefer. If your manual specifies piston drop before TDC, but you would rather set the timing using degrees of crankshaft rotation with a degree disc, this guide shows how to convert piston
Andy Marks
Mar 122 min read
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