These issues may now be resolved but mud tends to stick.
The one i recall is that the Boyer could be hard to start for one of two unrelated reasons. The first is that as a result of being timed at max advance revs they could sometimes be a little retarded at cranking speeds, the second is that early Boyers put ignition advance in at quite low speeds, causing all kinds of dramas. Both problems were curable - involving making sure that you had the right model Boyer for your cam (the problems particularly hit R100Rs and RT models where the owners had swapped cams after breaking off the "nose" (or misguidedly thinking that RS (or 90S) cams offered a pathway to additional power - as I recall nearly all early Boyer woes came down to cams being changed without also fitting the correct cam gear and takign note of the ignition timing difference between models. Just putting the old cam gear on a new cam (and remember in duplex cam days these were regarded as just about a "life of bike" part) and/or continuing to use the original timing marks on the flywheel were the major causes of dramas.
The second and separate cause of boyer woes was (and remains) failure to read the bloody instructions.
A brief digression. My wife's bike has a 1986/87 R80 engine fitted, it retains the 1979 R65 crank (to avoid having to buy a new gearbox) and has a "sports" grind cam fitted by the original owner of the R80 engine (and I only new that because the engine's PO thoughtfully left a piece of paper in a plastic bag tucked in one of the "voids" in the timing cover.
Now if you (as an example) had only ever had points ignition and superficially read the Boyer instructions, after fitting the thing you would fiddle around getting it started and then set the timing at idle. You might then wonder why it was gutless and slower than it had been with a tired R65 engine- so much so that you might end up thinking about the work involved to revert the "points in a can" Boyer conversion back to points.
Then, if you were lucky, the penny would drop and a closer read of the the cam notes and the reading of the spec for the R80 engine generally - A calculation of where max advance should be and a new mark on the flywheel - followed by setting the timing at max advance revs and the problems went away. - At idle the "std" timing mark isn't even visible which caused some consternation for a "real" mechanic who worked on it a few years back - a quick phone call set him straight.
