WE CLAIM:
1. An engine comprising a crankshaft having a magneto mounted on one side thereof, and an oil filter, wherein the oil filter is mounted on the magneto side of the crankshaft.
2. An engine as claimed in claim 1 further comprising a clutch; the crankshaft having a clutch portion near the clutch and a magneto portion spaced from the clutch; the oil filter being mounted proximate the magneto portion of the crankshaft spaced from the clutch.
3. An engine as claimed in claim 1 or 2 wherein the filter is a centrifugal filter.
4. An engine as claimed in claim 3 wherein the centrifugal filter is connected to or mounted to the crankshaft.
5. An engine as claimed in claim 1 or 2 wherein the filter is mounted to a gear or surface also mounted, either directly or indirectly, to the magneto portion.
6. An engine as claimed in any one of the preceding claims including a starting system having a 'bendix' drive comprising a drive gear; and a starter motor, an output shaft of the starter motor being engageable with the bendix drive gear on starting and the bendix drive gear being engageable with a ring gear that is fitted to the crankshaft enabling the starter motor to drive the ring gear.
7. An engine as claimed in claim 6 wherein the ring gear of the starting system is connected to the magneto portion of the crankshaft for reducing the length of the crankshaft and the width of the engine.
8. An engine as claimed in claim 7 wherein the centrifugal filter is connected to the ring gear on the magneto side of the engine, also allowing reduction in the length of the crankshaft and thereby reducing the width of the engine.

9. An engine as claimed in any one of the preceding claims wherein the engine transmission is a continuously variable transmission (CVT).
10. An engine as claimed in any one of claims 1 to 8 wherein the engine transmission is a non-CVT transmission.
11. An engine as claimed in any one of claims 8 to 10 wherein a filter cap or bowl of the centrifugal filter is mounted to the ring gear.
12. An engine as claimed in any one of claims 3 to 11 wherein efficiency of filtration in the centrifugal filter depends on the diameter or radial extent (and so the volume) of the bowl cavity in a plane of rotation perpendicular to an axis of rotation of the filter.
13. An engine as claimed in claim 12 wherein the bowl of the filter is provided with means to assist oil churning.
14. An engine as claimed in claim 13 wherein a plurality of projections, or fins, protrude from a wall of the bowl to enable churning of oil.
15. An engine as claimed in any one of claims 11 to 14 wherein the filter cap is covered by a magneto cover having a guide which maintains contact with the filter cap during rotation.
16. An engine as claimed in claim 15 wherein the guide is a centrally located guide bush which constantly maintains contact with the rotating filter cap.
17. An engine as claimed in claim 15 or 16 wherein the magneto cover and guide bush are also provided with an oil passage communicating with an oil gallery of the engine crankcase enabling inlet oil to be led into a cavity of the filter cap; and an oil delivery passage enabling filtered oil to be directed to engine components to be lubricated.

18. An engine as claimed in claim 17 wherein the oil delivery passage is centrally
located in the magneto portion of the crankshaft.
19. A centrifugal filter for an engine lubricating system comprising a filter cap
having radial extent or volume determined with reference to available space for
mounting the filter on a magneto side of the engine.
20. A filter as claimed in claim 19 wherein the filter cap is provided with means to assist oil churning.
21. A filter as claimed in claim 20 wherein a plurality of projections, or fins, protrude from a wall of the filter cap to enable churning of oil.

22. An engine substantially as hereinbefore described with reference to Figure 3.
23. A centrifugal filter substantially as hereinbefore described with reference to Figure 3.