Alpha Bearings Parts & Big-End Kits
Alpha Bearings built its reputation on the part of a British twin most likely to end a long ride early: the big end. Their kits are the usual answer when a crankshaft has been reground past the standard sizes, or when an owner wants a roller conversion in place of the original shells, and they are specified by measurement rather than by model.
We list Alpha components alongside the engine parts they go in with, so a bottom end can be ordered as one job rather than assembled from four sources. Which kit you need depends on the crankshaft in front of you rather than on the model, so it is worth having your figures ready.
Standard, reground, or converted?
Which Alpha part you need depends on what has already been done to your crankshaft. A journal reground to an undersize needs bearings to match that size, not the factory one, and a roller conversion changes what the rest of the bottom end has to suit. If the crank has been out before and you do not have paperwork for it, measure it.
What we list
- Big-end kits: roller and shell options for classic British twins and singles
- Bearings: main and journal bearings in standard and undersize
- Bushes and shims: components that go with a bottom end rebuild
- Related parts: gaskets, seals and fasteners needed for the same job
Send us your measurements
Journal diameter, the machine it came out of and whether the crank has been reground are enough for us to confirm the right kit. Guessing at this stage is expensive later, and a big end that has been assembled to the wrong clearance rarely gives much warning before it lets go. If your engineer has supplied figures, send those.