For years now I have wondered how the different pipes that are available for the RS50 stack up to each other in a fairly real world environment. Well I finally got off my ass last night and went full throttle on the test. I would like to take this opportunity to thank Chuck Cofer (chuckles from the forum) for his extreme amount of labor last night on changing pipes between runs and him making his RS75 available fo the test....even installing the new piston ring to ensure good results.
We chose to use the TP75 cylinder kit since the port timing is actually very aggressive and the TP75 is by far the most popular kit sold in the USA and probably world wide. Had we used a TP72, or a Malossi 68cc kit the "street" type pipes would have performed even better and the shorter "race" type pipes would have made less power since they are deigned for peak operation at rps's higher than the port timings of the street oriented kits.
If you use a TP72, Malossi 68, Airsal T6 or any of the other street oriented cylinder kits you will get best results from the street type pipes....especially good looking are the Lomas and the Leo...with the stock pipe preforming admirably well.
Here are all the pipes tested together in one graph...pretty cool:
All testing was done on the same bike. The bike in this test is equipped with a TP75cc cylinder kit, lightly ported and with a new ring installed for the test. The motor was also fitted with a TM24 flatslide carb kit jetted with a 200 main jet, this was intentionally lean to allow the full rev out potential of the motor since this was a pipe test. The correct main jet for these conditions (58 degrees, 18% humidity and 29.71 pressure) was about 220-230. The bike was run on VPUltimate4 fuel premixed at 28:1 with an octane rating of about 93-94. Reeds were TP carbon. Clutch is a Barnett. Ignition chores were handled by a completely stock system with stock USA spec CDI unit with fixed timing at 20 degrees BTDC from idle to 15,000 rpm. Most of the pipes in the test were brand new, the used ones were clean race use only pipes with little to no carbon build up. Jetting was not changed from pipe to pipe but if it had been the results would have been higher peak power and torque numbers but little over rev past the torque peak.
All pipes were brought to full operating temp on the dyno before testing began. This means a temp of about 600 farenheight at 5 inches down the header and at least 280 farenheight at the convergent cone prior to the stinger. Coolant temps were kept in the 50-60 degree C range. Case temps were all between 130-145 degrees farenheight. The TP cylinder was set up with a .75mm squish band width and the exhaust port opening 20mm ATDC. T1 and T2 transfer ports opened at 30mm ATDC and the total stroke was 39.3mm with an 85mm rod length from center to center.
The only pipe I did not get to test in this series was the Gianelli which has traditionally performed very well from 9,500rpm to a max of 13,500rpm.
The stock pipe was also tested with the stock silencer and with a slip on from an older Leo Vince three bolt system.
All testing was performed in 4 hours of back to back runs on the same bike to eliminate as many variables as possible