Hi , Is there a selection of rear sprocket sizes available for 1963 A65 Star, 4 bolt fitting type
I'm only aware of 4206331 (42T) and 68-6034 (43T)
The usual changes to drive ratio are on the engine sprocket or the gearbox sprocket.
I have a 42T rear sprocket but feel it could be geared up I'll have to check the engine and gearbox ones then see what's available
I raised the gearing on my A65, made it much nicer to ride and moved the vibration out of the normal range. I fitted the biggest gearbox sprocket I could get, I think its 22T, this is the easiest way to up the gearing. Mine was a late model and the case was cut behind the clutch so the 22T would fit. I don't know if this was standard on all A65s, someone will know or call SRM as they sell the 22T sprocket.
Ive checked mine 20t gearbox and 43t rear sprocket, was there a standard fitment when leaving the factory?
I think standard is 20 / 42. Depending on where you ride you may find the standard gearing a bit low. Fine in town and in hilly / country lanes but on A roads and motorways you will want a higher gear.
When your bike was sold in 63 only about half of the M1 was open and there was no other motorway. A roads (trunk roads) were often 3 lane not dual carriageway so there was a lot less need for a high cruising gear.
US export models were geared for a fast 1/4 mile so even lower gearing.
Hi,
I went up one tooth on the gearbox on a '51 Flash and an A65. It was enough to reduce the business of the engines at cruising speeds but did not compromise lower speed riding. Many miles and a great variety of terrain ridden covered and very suitable for both bikes.
Dave.
Thanks guys i'll leave it for the summer and change it in the winter time