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Roger 04 RT Roger 04 RT is offline
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Join Date: Oct 2015
Location: Naples, FL and Cape Cod
Posts: 143
Originally Posted by tm1100s View Post
Did some testing and there seems to be a little interest so this is what I came up with. I'll just post it here for whatever the interest is and also so Lennie can look and download but I'll send him the actual session in Picoscope format. I didn't get the detail I was looking for but this R1200S stock cam and gear should prove to be a good reading. Taken running on one cylinder just above idle. I couldn't get the R1100S to run on one cylinder even for a few seconds but I'll try it again tomorrow. The R1200S had very little problem running on only one. I marked up the waveform but rather than get longwinded right here, a better explanation is located at this site, with examples:

This is the actual running compression waveform. The area between the two peaks is one complete 720 degree four stroke cycle.

Other than the peaks at 'A' which is TDC compression stroke, the rest of the waveform is much flatter than the examples on the ATS website and from automobile engine. This test reads in-cylinder pressure. I suspect that because our bikes have virtually no intake manifold or at most a very small volume one between the throttle valve and the intake valves, and have very little exhaust backpressure to affect the in-cylinder pressures, almost the entire range of pressure readings is a little lower than auto engines. I'll try for better detail but this should actually have enough detail to see the differences in cam timing between stock and Lennie's changes. This was done with a Picoscope. Timing differences can be measured down to tenths of a degree. I also have access to that same equipment shown on the ATS site. It'll allow me to overlay the ignition and fuel injection operation on top of the valve timing data.

Sorry, I just find this stuff interesting. And, just for some other information, this particular test is becoming invaluable for diagnosing engine and variable cam timing issues with a lot of the new cars- flat cams, lifters, skipped/slipped belt tooth inline or bank-to-bank and even roller tappets found with a slightly out of round rollers causing misfires.

I'll post the Pico data file here later for Lennie and anyone else who wants to play with that using the Pico software.

The areas of interest are where the 180 degree line falls in reference to the exhaust valve opening (D-F) and the 360 TDC line falls in reference to the overlap (near G-H).
Bravo! Great start. Looking forward to the next set of data.

What about measuring pressure in a cylinder that is firing, at least partly. Since these are twin spark cylinders you could run on one plug (although the effective ignition timing would be retarded due to the lack of the second flame front).
Old 05-31-2018, 02:40 AM
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