Crankshaft Timing Degree Disc Wheel
The crankshaft degree / timing disc degree wheel is an essential tool for any vintage British motorcycle mechanic, as it allows for accurate engine position when setting magneto, points, or electronic ignition systems.
Thin poly-vinyl construction and oil resistant, with easily read graphics. The center hole can be enlarged for use on the crankshaft side of the engine. Single degree graduations for a full 360 degrees of rotation. Made in the UK from Wassell. The OD is 7.5″ while the pre-cut hole in the center of the disc is 1/2″, with circular templates graduated up to 1-1/4″. Can be easily cut to accommodate your application.
Useful for cam timing when marks are not present on the pinions and when setting up aftermarket or performance camshafts.
A pointer must be sourced and fitted to a stationary point on the engine calibrating top dead center. For use on the camshaft side of the engine, an adaptor must be fabricated or purchased separately.
Please note: Due the nature of the product, we unfortunately do not accept returns on bearings, service tools or electrical components. Please be confident about your purchase before ordering. If you have questions, please contact us.
The product images shown are for illustrative purposes only and may not be an exact representation of the product received. Manufacturers occasionally make minor cosmetic changes to items, such as color, finish, label, or design. These changes do not impact the item’s function or compatibility. Please contact us if you have specific concerns regarding appearance.
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Crankshaft / Timing Degree Disc Wheel FAQs
What else do I need to use this degree wheel?
The disc mounts on the crankshaft, but it doesn't come with a pointer. You'll need to make or buy one and fix it to a part of the engine that doesn't move, then set it at top dead center (TDC). The center hole is 1/2" and has cut-out guides up to 1-1/4", so you can enlarge it to fit your crankshaft.
To find TDC accurately, use a piston stop or a TDC tool such as our Triumph Norton BSA Ariel 14mm TDC Timing Tool (TBS-0112W) or the Triumph 500/650/750 TDC Timing Tool (TBS-6152). The usual method is called the positive-stop method:
1. Turn the engine by hand until the piston touches the stop, and write down the reading on the disc.
2. Turn the engine the other way until the piston touches the stop again, and write down that reading.
3. Add the two readings and divide by two. Move the pointer by that amount, and zero now marks true TDC.
Can I use it to set or check electronic ignition timing?
Yes. The disc gives you an accurate engine position for setting magneto, points, or electronic ignition systems such as Boyer Bransden. It's also worth using to check the factory timing marks, which aren't always right.
In one Norton Owners Club discussion, a rider set his ignition with the built-in crankcase scale and got a painful kickback. When he checked with a dial gauge, the scale was 3° off. The fix other members recommend is to find TDC with a timing disc, turn back to your timing figure (for example 28° BTDC), and mark the rotor yourself. https://www.nortonownersclub.org/forum/equating-degrees-tdc-mm-tdc
Will this degree wheel fit my Triumph, BSA, or Norton?
Yes. It's a universal 7.5" disc made in the UK by Wassell. It's thin, oil-resistant PVC with single-degree markings all the way around, and it works on most vintage British twins and singles.
Crankshaft side: enlarge the center hole to fit.
Camshaft side: you'll need an adaptor, which you can make or buy separately.
Triumph 650 and 750 owners: our Triumph degree wheel tools come in the right thread for each model:
650 Bonneville/Tiger, 26 TPI (TBS-0335 E)
750, 28 TPI (TBS-0335 L)
The disc is also handy for cam timing when the gears have no marks, or when you're fitting an aftermarket or performance camshaft.
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