Why The 1970 BSA A65 Is The Best Year
There are still many opinions today of which BSA A65 that was produced is deemed to be the "best" year. It appears today that everyone automatically believes that they have the best year A65 simply because they own it.
Brief History
Artwork of a BSA A65 unit twin engine - pulled from a period magazine article
Frame
BSA A65 "dry frame" blue print
Probably one of the best features for the 1970 was the "dry" frame. Just the next year in 1971 (also carried on in 1972) BSA designed and produced a new frame in which the oil was located in the center frame down-tube. Also known as the "oil in frame".
The oil in frame design ultimately put the nail in the coffin for the BSA motorcycle company and severely hurt Triumph during the fallout. BSA had control, influence, and power over Triumph at that time as BSA owned Triumph. Many are not aware that the Triumph oil in frame was designed by BSA.
There are many opinions on the oil in frame models. From a value point of view prices typically drop for BSA and Triumph models from 1971 and on due to the oil in frame design. Although the oil frame models handle very well they are not appealing and they also have there flaws.
Horns
Just like the 1970 Triumph Bonneville the BSA lightning was the only model for 1970 that featured dual horns. For those that are familiar with the dual horns they are called Clear Hooter horns which today are extremely difficult and hard to locate.
Although the 1970 BSA Lightning featured dual horns not all came equipped with them from the factory. Many where fitted with 1 single horn or dual "thunderbolt" horns which where different in style, shape, and sound.
Lightnings that came equipped with dual horns had a special head stay bracket in which one could fasten the Lucas 6RA horn relay for the dual horns.
Base Studs
3/8" diameter base studs along with 3/8" size 12-point base nuts
The cylinder base studs in 1970 where changed from the smaller 5/16" diameter to the larger 3/8" diameter. It only took BSA 7 years to make this change - should of been implemented sooner.
The larger diameter base studs allowed a higher torque rating on the cylinder barrel. I heard of one instance in which a cylinder barrel lifted from the crankcase on an early model that had 5/16" studs... according to John Healy.
The 3/8" base nuts where also changed from standard hex to the new 12 point nuts to allow easier adjusting when using a box end wrench.
Cylinder Barrel
Cylinder barrel fin cutouts as seen on this 1970 BSA A65
Never seen before until the 1970 - A65 models where now fitted with cylinder barrels that featured cutouts above the cylinder base nuts. This change was also carried through 1972.
This new change allowed easier access for a box end wrench to slip over the base nuts. Previous years did not feature this design which made it more challenging to slip a wrench between the base of the barrel and over the nut.
Late barrels from 1970-1972 are getting harder to find today as they where only used for 3 years. They are not interchangeable with early models as they are suited (and offset) for the 3/8" diameter base studs.
Stud Pattern
We now know that in 1970 BSA A65s now had the larger 3/8" base studs. Although the design is similar to that of the 5/16" studs, cases with 3/8" studs have an offset pattern.
Clutch
New clutch set-up on the 1970 BSA A65 - very similar to Triumph twins
The new clutch actuator allows a much smoother feel on the clutch lever for a more positive clutch release.
Notice that the outer timing cover has been changed as well. Inspection plug and an extra fastening screw - new for 1970.
Coils
Smaller Lucas 40MM diameter coils and bracket - new for 1970
Normally 48MM Lucas coils where fitted to A65 models - 1970 A65's where fitted with smaller 40MM coils as usually found on most Triumph and Norton models. I am not exactly sure why this change was implemented. I can only assume that perhaps the large Lucas coils where not available or where to expensive.
The coil bracket to house the smaller Lucas coils where also changed making them a "one year only" part. 40MM coils and brackets are listed in the 1970 BSA 650 parts book only.
Mirror Holes
Mirror holes on both the clutch and brake perch - new for 1970
Mirror holes on both the clutch and brake lever perch was a new design for 1970 models. Most laws in the USA (depending on the state) require to have at least (1) mirror on either the clutch or brake side. Mirror holes shown above accept an 8mm threaded mirror.
Earlier BSA models prior to 1970 did not feature this clutch and brake lever perch design. To adapt a mirror you would have to use the "clamp-on" style mirrors.
Conclusion
If you're familiar with early BSA A65 models I'm sure that you can come to the conclusion and agree with me that the 1970 BSA A65 is the best year based off of this information and experience.
From a buying, selling, and an investment point of view I personally feel that all 1970 BSA A65 models are the best choice. 1970 models retain there value better than any other year (except rare models) especially the 1970 BSA Lightning.
So there you have it - my 2 cents on why the 1970 BSA A65 is the best choice. If there is any information that I missed or did not touch on, please let me know by commenting below. I would appracite everyone to chime in using the section below. As always, thank you for reading today's blog post.
Classic British Spares
@Scott – I agree with you 100% The 1970 is the best and last year for the more “traditional” BSA. I have a fancy for the 71-72 OIF twins. Although the OIF is not eye appealing they are more “modern” considering what BSA was producing just a year earlier. I hope all is well with you. Thanks for reading and commenting!
Scott Dundas
This subject will always open a can of worms! I think that the 70 model was the last of the traditional looking Beezas. However the only real difference between the 70 model and the 71/72 models was styling with the Later models having oil in the frame, indicators, breadbox tank and chrome guards. The OIF idea was ok but just didn’t carry enough oil ! Which was a problem in hotter climates outside the U.K. The 71/72 twins needed at least another pint of engine oil and an oil cooler as standard like the Rocket 3. The engines and electrics were basically the same in 71/72 as 70. Therein lies the problem. When Honda was offering trouble free leak proof bikes with electric starts, good suspension at an equivalent price to BSA , it was only a matter of time before BSA Triumph and Norton were gone . I like the preunit A10s for styling over the unit construction A65s. Unfortunately the poms didn’t realise that simple styling changes wouldn’t cut it against improved motorcycle technology