For the motorheads: If I was to B&B my stock engine what could I expect to see in improved redline and power? Also I would expect to see some reduction in vibration, no?? At this point I'm only dreaming. I know Tyler did his at PCW, re-sleeved to 1260?? and the results are great. Wayne H Pettipas Tel 613-596-9473 Fax 613-596-9969 E [EMAIL PROTECTED] VMOA--#1266
Hal, If you want a really true calculation then the measurement should include the entire loaded vehicle. The 12.47 figure that I use for a stocker is from a Cycle World test indicating 809 revolutions per mile with the K525 on the bike. This is a typical value to use for a stocker since this is supposed to reflect the results of a stock tire. If I used a 591 or something similar .... which is advertised as having a 25.6 diameter then I doubt that it would lose 1/2 inch sitting on the ground .. but what do I know. That is why you will get different results ... if this tire only compressed 1/4 inch then the rolling diameter would be 25.6 / 2 = 12.8 - .25 = 12.55 .... this .08 difference would yield a 5th gear RPM of 4404 at 70 mph as opposed to 4433 for the dunlop, (a more exact RPM calculation than the 4450 I stated earlier). Assuming you have no clutch slip .... the gearing on the stocker is a known value .. so an easy way would be to simply see what RPM you are turning at that speed and calculate the "rolling radius" from that. Unfortunately, this is no easy task with the mini-tach .. and is why I really rounded the RPM off to 4450 as I doubt anybody can tell the difference between 4433 and 4450 or our stock tach. Also .. the chances of 70 mph actually being exactly 70 mph is questionable. Soooooooo .... sitting the bike on the ground ... having someone sit on it or simply hold it up ... and measuring from the center of the rear axle to the ground will get you pretty darn close for most purposes. An even easier way is to put a mark on the sidewall of the tire with your favorite dragstrip white shoe polish and the ground ... roll the bike forward until the mark rotates around again to touch the ground ... measure the distance between the two marks and you have a pretty accurate "rolling circumference" like Eric was talking about ... and that work just as well, (if not better). The "rolling" circumference is infact 2 x (rolling radius) x (pi) so to derive the "rolling" radius from that would simply be .... (rolling circumference) / 2 x (pi) ... Back to our stock tire .. if we did the "mark on the ground" routine .. we should have recorded a distance of 6.53 feet or 78.36 inches ..... plugging that into our formula we have 78.36 / (2 x 3.14) = 12.47 ......... Hope that helps ... campbell ----- Original Message ----- From: "Hal" <[EMAIL PROTECTED]> Subject: RE: Rpm at 70 > TC, > Is that 12.47 a static measurement? Does it include the > rider? Is tire rise at high speed ever significant enough to > be a factor? > -----Original Message----- > From: TC [mailto:[EMAIL PROTECTED]] > Subject: Re: Rpm at 70 > > Eric, > The rolling radius is the distance from the center of the axle > to the ground with the bike sitting on the ground. 12.47 is > the advertised rolling radius of a Dunlop Qualifier K525 ... > If you want to talk distance per wheel revolution I'll take that > too .. for the 12.47 rolling radius stock tire that would be 6.53 > feet. ............................................. To unsubscribe go to http://www.sayegh.org/unsubscribe.htm .............................................
