I think more about crank angle than the rod buckling. The rods being made today are great. Cylinder filling is important, so that tends to speak well of increased dwell. Though increased dwell at BDC tends to lead to more charge short circuiting as well - a mixture of the old and new gasses. So, is it the rod length that seems to provide better power through the mid range or is it the longer dwell which increases the cylinder filling time which creates it? As it turns out both - you can't increase the rod length without increasing the dwell.

Using the 10 mm longer rod and 88 piston and base plate spacer is an interesting combination. It's unusual for a rod to be much more than twice the length of the bore. With a 66 X 72 combination the 125.3 mm rod would have the engine open its ports at 89.5 degrees ATDC, increase the rod length to 130.3 mm's and the exhaust timing changes to 89.9 degrees. Add another 5 mm's (135.3) and the timing gets mellowed out even further. It now opens the exhaust at 90.1 degrees ATDC. As you can see, rod length affects everything - so even when you keep the distances the same, it changes the timing. These are just the numbers for the exhaust ports. The transfer ports would be as follows - 125.3 mm rod = transfers open at 120.1 degrees ATDC, add 5 mm's to the rod and the transfers now open at 120.4 degrees. Add another 5 mm's and it changes to 121.0 degrees. Again, mellowing out the engine.

Long rod motors allow for more radical port timing with less power hit when on the pipe. It also tends to move heavy vehicles a little easier. That could be a side benefit of the decreased rod angle as well as decreased friction or both. To get the best of both worlds in the TRX it's best to use the early barrels with their "big mouth" inlet opening, or should I say friction reducing but piston wearing out sooner opening. All this data and still I prefer the short rod engine and early model barrels. When going from point "A" to point "B" the fastest, I'll take the short rod version of the TRX engine every time.

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Rod Length and Rod Angle