"A local bike-shop bought that 650cc racer with the blown engine from Ed and they were pissed because there were no racing parts in the engine, Ed had just blueprinted the engine and modified the stock parts so they worked much better, he also did lots of testing at the drag-strip to get the exhaust and intake-tract length optimized which he said made a big difference in power."
This isn't a surprise at all. Back in period there wasn't much available unlike today.
Most of the period race engines that are road / production based used modified internals. The Norton twins' weak point was conrods and crank but by 1961 Norton start fitting nodular iron cranks (spherical graphite) to it sports bikes 88ss, 99ss and 650ss, also other AMC twins like Matchless and AJS CSR twins too. This pretty much sorted the crank braking issues. Rods were still suspect however so were regularly changed but always balanced and polished.
Nimonic steel valves were a usual mod (factory race kit and available to buy) much stronger than standard and perfect fitted valve spring length by shimming under the lower cup. There wasn't a huge amount you could do regarding camming either, as wide-ish valve angles made radical timing almost impossible without pocketing valves / pistons and loosing compression. As for race pistons? There was virtually nothing available so standard high compression SS pistons with a head skim either 20, 40, 60 thou to raise the ration a little more was also normal. But even standard high comp 650ss pistons are a difficult find today. Its fair to say that most internal engine mods were about reliability and not purely seeking peak horsepower. Utilisation of inlet and exhaust pulse was were most radical work was done by factory and home tuner (if they had the money).
Interestingly Triumphs Thruxton T120 bikes from 65 (factory specials) were quite standard except for cams and followers, 40 or 60 thou head skim, a good port shape and 1 3/16 monoblocs, with stepped down small bore header pipes (with balance) all good for 135mph with a fairing. Likewise AJS and matchless factory prepared racers were similarly prepared. Or rather nothing special. I have owned a genuine Triumph Thruxton Bonneville from 65 and AJS Model 31 CSR Thruxton from 61.
I guess when thinking about some of these older bikes you have to set aside modern ideas and think "period".
If the bike is looking for a new home, it can come over this side of the pond and live in my workshop and in the company of Manx's, race Domi's and even the odd XRTT after a little sympathetic and gentle preservation.
This isn't a surprise at all. Back in period there wasn't much available unlike today.
Most of the period race engines that are road / production based used modified internals. The Norton twins' weak point was conrods and crank but by 1961 Norton start fitting nodular iron cranks (spherical graphite) to it sports bikes 88ss, 99ss and 650ss, also other AMC twins like Matchless and AJS CSR twins too. This pretty much sorted the crank braking issues. Rods were still suspect however so were regularly changed but always balanced and polished.
Nimonic steel valves were a usual mod (factory race kit and available to buy) much stronger than standard and perfect fitted valve spring length by shimming under the lower cup. There wasn't a huge amount you could do regarding camming either, as wide-ish valve angles made radical timing almost impossible without pocketing valves / pistons and loosing compression. As for race pistons? There was virtually nothing available so standard high compression SS pistons with a head skim either 20, 40, 60 thou to raise the ration a little more was also normal. But even standard high comp 650ss pistons are a difficult find today. Its fair to say that most internal engine mods were about reliability and not purely seeking peak horsepower. Utilisation of inlet and exhaust pulse was were most radical work was done by factory and home tuner (if they had the money).
Interestingly Triumphs Thruxton T120 bikes from 65 (factory specials) were quite standard except for cams and followers, 40 or 60 thou head skim, a good port shape and 1 3/16 monoblocs, with stepped down small bore header pipes (with balance) all good for 135mph with a fairing. Likewise AJS and matchless factory prepared racers were similarly prepared. Or rather nothing special. I have owned a genuine Triumph Thruxton Bonneville from 65 and AJS Model 31 CSR Thruxton from 61.
I guess when thinking about some of these older bikes you have to set aside modern ideas and think "period".
If the bike is looking for a new home, it can come over this side of the pond and live in my workshop and in the company of Manx's, race Domi's and even the odd XRTT after a little sympathetic and gentle preservation.