Where can I find my bike frame and engine number?
By Dr Ken German
Previously an officer in the Metropolitan Police Stolen Car Squad
27.12.2018
Buying a classic motorcycle can open up a whole new world of biking – machines with none of the electronics or fancy fuel injection of modern bikes, and with the potential for many happy evenings of tinkering in the garage. But making sure you’re getting one with that is what it claims to be can be harder, thanks to the fact that the frame and engine numbers can be in some pretty unexpected locations.
On modern machines it’s usually a simple case of checking the headstock and the rear of the engine, so this guide will show the exact position of most bikes that now have ‘classic’ status, or in the case of mopeds, scooters, flat twins etc, an approximate position…
Depending on the bike, locations to look for the numbers are:
Headstock
Nearside top of crankcase below barrel(s)
Top of crankcase behind barrel(s)
Cross member below tank/saddle join
Front of crankcase
Approx position only
Top nearside of crankcase behind barrel
Nearside frame down-tube below headstock
Offside top of crankcase below barrel(s)
Cylinder head
Offside rear fork leg in front of wheel spindle
Approx position
Front nearside of crankcase
Front nearside frame down-tube on lug
Recess under nearside crankcase
Offside radiator frame loop
Reynolds fork approx position
Under offside of crankcase
Under and forward of nearside crankcase
Nearside rear fork assembly near wheel spindle
Nearside down tube lug
Offside frame down-tube below head stock
Offside crankcase cover
Where to find your motorbike frame or engine number
Using the image above and the following key, you should be able to look in the correct location for almost any model of classic motorcycle. The numbers correspond to the picture above, while the codes mean the following:
As an example, 1FS-2ES shows that the frame number is stamped into the frame (FS) at position 1, and that the engine number is stamped into the crankcase (ES) on the nearside barrel at position 2. You will find variations in locations for some brands – BSA for instance has three possible frame number locations and one for the engine. The numbers represent the area to look – number 24 for instance is where the frame meets the top tube.
This is intended to be a guide for those who aren’t experts in each marque, but we do welcome any updates or additions – please drop us an email at enquiries@bikesocial.co.uk
Motorcycle manufacturer’s frame/engine number locations