120/70 on a 620ie?

[Nickj]

Originally Posted by Dukedesmo

Same sized wheel as other bikes so why not the tyre?

I recall back in the 916 and 748 days, the bikes used the same frame, suspension, wheels etc. yet 748s were fitted with a 60 profile front whilst 916 a 70 profile, similarly, at the rear 748 had a 180 width whilst 916 a 190 width.

It wasn't long before most adopted the 70 profile front and 180 width rear for both, my understanding was that they tried to sell the 748 as a more nimble bike (presumably to compensate for less power?) and fitting a lower profile front and narrower rear made it tip into a corner quicker but it soon became apparent that it ran out of front tyre/grip sooner due to the lower profile. The narrower rear, however was a good thing.

I can confirm that the 748's, certainly the R's, are faster .. much faster.. into corners than 916's. Fitting the fatter rear profile trashes the handling. The power difference isn't that significant a good 916 has at best 9bhp at the limiter over my R. They're a much closer match than you'd imagine and that edge into corners and the insane corner speed they'll carry is a great leveler. The fast spin up of the 748 motor virtually compensates for the torque difference.
I like the 916's and the 748's, take the stickers off and you'd not know which was which without a close look.

[Dukedesmo]

Originally Posted by Nickj

I can confirm that the 748's, certainly the R's, are faster .. much faster.. into corners than 916's. Fitting the fatter rear profile trashes the handling. The power difference isn't that significant a good 916 has at best 9bhp at the limiter over my R. They're a much closer match than you'd imagine and that edge into corners and the insane corner speed they'll carry is a great leveler. The fast spin up of the 748 motor virtually compensates for the torque difference.
I like the 916's and the 748's, take the stickers off and you'd not know which was which without a close look.

I would say it's all in the setup.

Tyres being equal and engine power aside what is the real difference between the bikes with regards to geometry and weight? because the chassis is the same, the engine is the same other than a few internal components and the weight difference is minimal (basically the weight of the missing oil cooler and 1/4L of oil on a standard 748).

Now a 748R will have better suspension components and some weight savings over a standard bike along with more power and the more rev-happy nature should make it easier to get on the power whilst the the larger engines have more torque - making it easier for the less race-focused.

But given that most people (that I've met) run the 180 rear/70 profile front combination regardless of model then any differences must be largely down to setup and, of course the size of your testicles...