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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.
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
Oil Tap with Cutout Switch - Dimensions
Our oil taps are available in two configurations. Either Male to Female or Female to Female. Each of these configurations are available in two sizes, giving a choice of four taps in total. 1/4 BSP Male to Female 1/4 BSP Female to Female 3/8 BSP Male to Female 3/8 BSP Female to Female Kingpin Oil Tap with Cutout Switch Dimensions 1/4 BSP Oil Tap Dimensions 1/4 BSP threads measure 0.518" (13.16mm) outside diameter (OD) and have 19 teeth per inch (TPI) Both types of 1/4 BSP taps
Andy Marks
Mar 101 min read
Workshop Update - February 2026
I had a lot of time out of the workshop this month - but we've still got work done so here it your latest update.
Andy Marks
Mar 24 min read
Calculating Cylinder Displacement and Compression Ratio
Learn how to calculate cylinder displacement and compression ratio for classic and vintage motorcycle engines. This guide explains the practical method to use your engine’s bore, stroke and combustion chamber volume to determine swept volume and static compression ratio, and outlines how to measure combustion chamber volume accurately. Most standard production machines will have these figures clearly stated in the owner's manual. However, if you are fitting non standard par
Andy Marks
Feb 82 min read
Workshop Update - January 2026
The first monthly update of 2026 - see what we've been up to in January
Andy Marks
Feb 16 min read
Making New Girder Fork Spindles
This article explains how to approach making new girder fork spindles for vintage motorcycle suspension, focusing on correct material selection (EN16T or EN24T) and why unsuitable steels like free-cutting mild steel, silver steel or stainless should be avoided. It also highlights why it’s preferable to source ready-made spindles if available. Why Buying Ready-Made Spindles Is Often Better Making a one off set of girder for spindles can be time consuming and expensive. There i
Andy Marks
Jan 292 min read
Repairing Worn Girder Fork Damper Threads
These threads often rattle and wear. Here is how we repair them
Andy Marks
Jan 292 min read
How to Fit Girder Fork Bushes
When girder forks that were not originally fitted with bushes wear, it's time to fit a set of bushes. Here's how we do it.
Andy Marks
Jan 272 min read
Welcome to the Kingpin Components Blog
What you'll find in the Kingpin Components Blog and why you should read it
Andy Marks
Jan 222 min read
Smart Diode Cut Out
Learn how to install and use a smart diode cut-out on vintage and classic motorcycles. This technical guide includes fitting instructions and specifications to ensure correct electrical operation during restoration and routine maintenance. For use with three brush dynamos, some Miller two brush dynamos which use separate regulator and cut out units and all dynamo systems which use permanent magnets for the field including the ML/Lucas Maglita units. Included with every cut o
Andy Marks
Dec 23, 20252 min read
Oil Tap with Cutout Switch
Our combined oil tap and switch which prevents wet sumping and can be connected to bikes with magneto or coil ignition. This ensures that, if the oil tap is 'off', the switch will stop any sparks and the engine cannot be started until the oil is switched on. Included with every tap we sell is a comprehensive instruction sheet. If you have misplaced yours or would like to take a look at how to fit one before buying, please read on. If you would like to download a copy to print
Andy Marks
Dec 22, 20252 min read
Magneto Static Timing Light
This guide explains how to use a magneto static timing light to accurately set ignition timing on vintage and classic motorcycles. Designed for use with all makes of magneto, and battery/coil equipped engines, these instructions provide a clear, reliable method for checking and setting timing during restoration or routine maintenance. The very best performance from an engine can only be obtained if the ignition timing is correctly set. Over-advanced ignition will make the eng
Andy Marks
Dec 22, 20253 min read
Magneto Vernier Sprocket
Using a Kingpin Components vernier sprocket for setting the ignition timing on your vintage or classic motorcycle makes getting your timing spot on considerably easier and far less time consuming. The use of this vernier sprocket allows fine adjustment in increments of just 2.35° rotation of the crankshaft. The vernier sprocket has a major advantage when searching for that last ounce of performance. When experimenting to find optimum ignition timing, if testing shows that you
Andy Marks
Dec 22, 20253 min read
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