Motorcycle tuning four strokes by John Robinson
- Thread starter Bernhard
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I've never read anywhere about advancing and retarding camshafts to find the optimum to suit the exhaust and inlet systems. It is something that I did with my short stroke Triumph to find more torque. The only thing that worked was to ditch the separate pipes and megaphones and use a 2 into one pipe with a long single megaphone, then fiddled the cams. I also cut the collector back in stages. I lost about 1500 RPM off the top however I started to get much better lap times.
It is mentioned in 'Tuning for Speed', most recent versions being by Phil Irving.
He specifically mentions and shows the vernier cam adjustment arrangements in the Norton International (ohc (cammy) 500cc single cylinder).
In that engine, THE INLET CAM TIMING can be advanced or retarded, to suit a straight pipe or muffler (or megaphone).
The inlet timing in those engines can make a considerable difference, where it is not recommended that the exhaust timing figure is altered at all.
In more recent proddy bike racing, it was found that some Z900 exponents were reboring the cylinders slightly offset to stock.
This had the effect of giving slightly advanced inlet timing, a few more ponies and thus a slight advantage.
Took very detailed scrutineering to pick that one up - some bikes obviously had an advantage, and they went looking for it...
Lotta cars and bikes these days have V V T badge on them = variable valve timing etc.
Quite complex these days, they have come leaps and bounds in this field.
Even to having power valves in the exhaust, that can open and close (to an extent), to boost power in some rpm ranges...
A review of the book mentioned above above.
http://www.amazon.com/Motorcycle-Tuning ... ewpoints=1
He specifically mentions and shows the vernier cam adjustment arrangements in the Norton International (ohc (cammy) 500cc single cylinder).
In that engine, THE INLET CAM TIMING can be advanced or retarded, to suit a straight pipe or muffler (or megaphone).
The inlet timing in those engines can make a considerable difference, where it is not recommended that the exhaust timing figure is altered at all.
In more recent proddy bike racing, it was found that some Z900 exponents were reboring the cylinders slightly offset to stock.
This had the effect of giving slightly advanced inlet timing, a few more ponies and thus a slight advantage.
Took very detailed scrutineering to pick that one up - some bikes obviously had an advantage, and they went looking for it...
Lotta cars and bikes these days have V V T badge on them = variable valve timing etc.
Quite complex these days, they have come leaps and bounds in this field.
Even to having power valves in the exhaust, that can open and close (to an extent), to boost power in some rpm ranges...
A review of the book mentioned above above.
http://www.amazon.com/Motorcycle-Tuning ... ewpoints=1
Fast Eddie
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I have the second edition which has quite a bit of info on changing cam timing, re-profiling etc. maybe that's the one you had in mind.
Thanks for your reply.
Once again I am looking specifically for the one edition which came with specific engine mods that you could carry out on certain specific models. I will know it when I see it, as it does not appear in any of the other editions.
Once again, thanks for your reply
Once again I am looking specifically for the one edition which came with specific engine mods that you could carry out on certain specific models. I will know it when I see it, as it does not appear in any of the other editions.
Once again, thanks for your reply