AlisoBob wrote:The piston is reciprocating....
A::roll:
B: There is no gyro effect....
C: Chain tension ( acceleration / coasting / decelerating) effects suspension reaction.
D: C/S position has little , if anything , to do with it.
E: Motor clocking will slightly effect the bikes center of gravity, but I doubt its enough to ever notice.
I like all these theory's though....
seanmx57 wrote:
IMO how the motor is clocked is the most overlooked aspect of AF.
I've seen your A/F's.... I'd say proper assembly proceedures is whats being overlooked.
Aa:
Go to the dictionary = Reciprocate - to cause to move alternately back and forth .There are quite a few other definitions, for the word, but that is the pertinent one, in relation to this thread.
Ba: - Piston / Pin / LE brg and much of the rod, have significant , alternating thrust forces, that also deliver a rocking effect and alternating giro effects. It can have a marked effect on vehicle dynamics.
Sections of these parts, deliver "Gyro effects", not only the crank and all items attached to it, as well as clutch, gear shafts , gears, partial brg sections - but, we all know that, about the obvious parts. Dealing with the engine here, only.
Ca: Well, you've got that one right!
Da: Well, you've got that, Entirely wrong.
Change the CS position, from what the original one was in the frame you are using, and you will change the suspension performance. Make it higher, and you increase the squat effects, both overall force, and when the pro-squat, takes over.
The above, a higher CS height than std, is The Classic Eff up, that many people do. When you see a bike with the Honda emblem on the clutch cover, angled upwards, at the 'DA' end, you've got the Classic Eff Up, right there in front of you.
CS height, and CS centre to SA centre, is a major tuning aspect. See the amount of Road Racers / Superbikes with adjustable SA pivots.
I'd say, if tech battles between manufacturers ever heat up again, adjustable SA pivot points, will appear on MXers.
If you Are going to change the CS centre height, the preferred change, is to lower it, especially when fitting a much higher HP / Torque engine. Look to the changes Honda made with the 09> CRF450 - I think it was a 5mm lowering of the CS centre, from previous. I'm not sure if the Gen5 250 had the same changes - I'd be surprised if it did not.
There's the possibility of changing the CS centre, to SA centre, distance too, (but this is limited), through off centre Case Spacers, and off centre Case holes.
As a side note, chain roller position, and diameter, has significant effect on chain torque, and on the suspension action. Predominantly the upper roller, but, not excluding, the lower roller.
Ea: Well, it certainly does, and, as the distance of the crankshaft centre, and top end components to the SA pivot point/ engine pivot point, is higher than the SA pivot / case interface, these points are moved more than the CS height. If you couldn't feel the difference, in the engines height, when the engine is rotated , say, with a lowering of the CS pivot, relative to the SA pivot by 5mm, giving a rough height lowering of 20mm at the front top of the cylinder head , and approximately 11mm, at the crank centre , I'd be certain that I had a bloke who wasn't much of a 'thinking' , or 'perceptive' rider.
Sean, is dead on with his comment - for the reasons, I've shown, above.
But, for blokes who think that CS height, does nothing to your handling, I'll leave you to your beliefs. As is often said, ignorance, is bliss. And, pride of ownership / of ones building efforts, can cause ignorance.
As for 'mating' an earlier generation cradle, to the Gen 5 - just make a new cradle. $30 / $40 worth of tubing, then bent, is much cleaner, and stronger, than cobbling more parts together.
musta put a lot of R&D hours on that one
