Re: Suzuki LS650 - only 30hp???

Albrecht via MotorcycleKB.com wrote:
Rafael wrote:

Wouldn't the stroke give you the linear velocity of the
rings for a given RPM?

This formula gives you the mean piston speed.

Cm = 0.166 X Stroke X RPM

Cm = 0.166 X 3.7 X 6500 = 3992 ft/min

Peak piston speed at 90 degrees ATDC might be as high as 8000
ft/min but that doesn't cause ring flutter because the piston
has accelerated to its peak speed and is beginning to slow
down gradually.

Ring flutter is worst at TDC when the ring keeps going as the
piston comes to a stop at the end of the upstroke.

Rod angularity causes piston rocking, but the peak pressure in
the cylinder is falling off at 90 degrees ATDC.

I think the Savage engine might survive being run up to 7400
RPM, where it would have 47 horsepower, but I need information
about the center to center dimension of the connecting rod.

If the center to center dimension of the rod is 7.5 inches, it
looks like Gmax is 98730 ft/sec^2 and the Savage engine will
encounter the onset of ring flutter at 106000 ft/sec^2.

Gmax = { (RPM^2 * stroke) /2189 } * 1 + the reciprocal of 2 *
C-to-C

Suzuki rates the LS650 redline as 6,500 RPM. I have oversped it a few times by accident without apparent damage, but am reluctant to purposely push it beyond 6,500 RPM.

I would think that once one pushes it beyond manufacturer recommendations is only asking for trouble. Possibilities could be entrance into plastic deformation region of the metal and embrittlement from work hardening. Then cracking and possible separation (grenading) occurs.

It is safer to remain within safe limits of the spring range of the metal and within safe limits below that of cyclic fatigue.

Keith mentioned something of a circulating system problem with his.

--
Cheers, Rafael
.

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