The Classic Motorcycle
My enquiry is a request for help restoring a 1922 211cc Levis Popular, specifically in relation to the belt rim, drive pulley and flywheel measurements, which are all missing from this project. I cannot find a Levis club, period literature doesn’t give precise measurements and specialist vintage clubs haven’t been able to help. Any advice gratefully received.
Here’s a précis of advice I’ve passed onto Sean, gleaned from over 50 years of vintage and veteran motorcycling.
While period sales literature, owners’ guides and maintenance manuals will provide little or nothing to help quests such as Sean’s, often they include side-on sketches of the machine, from which components can be scaled from known dimensions, such as outside diameter of the tyres. However, one must remember such material has sketches or artist touched up photos of models, which may vary from what was actually made.
Literature-wise, the best help I’ve found for veteran and vintage machines are the ‘How To’ books such as ‘Motor Cycles and How to Manage Them’ published by the weeklies, and the late Frank Farrington’s (Radco) book ‘The Vintage Motorcyclists’ Workshop.’
But none of these will help
When we undertake the remaking of veteran, vintage and even some later machines, we have to accept some specifications quoted are like the sales brochure images – so best taken with a pinch of salt – as makers altered specification during, or even before, production, for a variety of reasons, including economy, the use of what was available to them and improvement of design. Additionally, the manufacture of spun, rolled etc items such as mudguards, wheel rims, belt rims, other tinware … was never that precise, due to the operators’ accuracy, the limitations of equipment and, if wheel rims, for example, were sourced from more than one maker, there would be further variance. An accuracy of 5% variance could in these cases be regarded as ‘accurate!’
Then makers offered alternatives to standard design to suit specific needs and applications. For example, Villiers offered heavier flywheel magneto flywheels to suit off road trials work, where engines were needed to run smoothly at much lower revs than for roadsters.
And experience of accumulating a few mechanical spares for my 1924 550cc OEC’s Blackburne engine confirms differing weight and diameter outside flywheels for this and other engines. I’ve run this machine on outside flywheels as light as 8½lb, which yield faster engine pick-up at the cost of less torque and lumpier running in the low rev range. Using a
14lb flywheel of near-identical diameter has had almost no effect on engine pick-up, but gives more torque and smoother slow speed running.
Doom mongers state the crankshaft main bearings (bushes) will wear much quicker, to which I can only reply, ‘They haven’t yet.’
One assumes if Blackburne offered a choice of outside flywheels for their engines, so too would the Butterfield family when they made Sean’s Levis. Thus, the following can only be a guide.
Levis specifications state the 1922 Levis 211cc Popular (direct drive) had a transmission ratio of 5 3/4 : 1 (5.75:1). From photographs we know the Popular was shod with 24x2 inch tyres which will give an inner wheel rim diameter where spoked of 19½ to 19¾in (19.5 to 19.75) and the fact there is precious little daylight between belt rim mounting flange and the wheel rim we can assume, with some accuracy, the business part of the belt rim will have an outside diameter of approximately 18in, to which the mounting flange of a depth of ½ to ¾ of an inch is added. Once the belt rim is established, the desired engine belt pulley size can be calculated. At this stage, I’d ask my daughter for help, as I secured my maths O’ level pass in a raffle...
From photos, one can deduce the Levis Popular had an outside flywheel diameter in the order of 10½in, and having weighed the flywheel of a 1918 269cc Royal Ruby and other like machines during engine strips, they’ve all scaled in at 8 to 8½lb. One assumes the Levis Popular will be similar.