Ace, I would appreciate it if you would go into the flow or wave dynamics of exhaust technology, particularly as it applies optimizing combustion chamber filling. Most Enfield owners go to a free flowing exhaust. However, more modern systems are using 2-cycle expansion chamber technology and flow formulas for the exhaust systems to aid scavenging as well as well as intake. In high-revving engines this type of exhaust allows for wilder cam timing yet still manage to produce a relatively wide power band. Taken to extremes these exhaust systems even have variable valving in the system itself to change resonance frequencies at different RPM. How would any of this technology benefit a low revving engine such as the Enfield? Would a tuned expansion chamber allow for more effective use of existing cams and port sizes?
Ace, when I asked about variable valves I meant that some modern bike have a valving mechanism actually in the pipe after and in addition to the exhaust valve. It does not completely block the port but rather is a relatively small restriction in the port. This restriction changes with RPM and throttle setting with more restriction at low RPM and less at high RPM. Two stroke engines drive this with gears driven by a Sprag clutch. Four stroke engines are usually computer/servo controlled. Less refined systems could be throttle cable controlled. Would this be of help or even be worth the trouble?
SO, I was wondering about slightly enhanced cams instead of "performance" and "full race" options. Designing a new cam is a little more involved than just adjusting the Duration, Overlap, Lift etc. Would it be easier (less expensive) to design and produce a higher ratio rocker? I don't know the ratio of the RE rockers but say something modest like going from 1.5 to 1.6? And if someone was were going to do this, how about a roller?
Ace, wow-wow-wow! That's some great technical writing and explained in a way that most will grasp. Will the installation of the adjustable cam spindles and the re-phasing of the cams bring the HP up to Redditch specs on a stock motor or is it in conjunction with the high comp piston? Also, are you planning on installing a set of these spindles yourself? This has been a very entertaining thread, keep up the good work! Blltrdr