Scooterotica

People often mention that they use a longer con rod with the Rapido Classic kit, 115/116mm, so as to tame the timing and have it run smoother.
I am just over half way through break-in and can see (feel) the need to smooth it out eventually.

Is the end goal to make it so the top of the piston (Not the crown) reaches the top edge of the cylinder then you know that everything else will be as it should?

My setup is with a 107mm con rod and the 2 ring Asso piston from AFR.

Curious as to how other Rapido users setup their motors, con rod lengths, piston skirt modification etc.

Cheers

The end result should be that it rides how you want it to. End of. A Rapido Classic has good port timings all round provided you're using the full skirt piston. Depending on final ride choice pretty much any combination of porting can be achieved, even without changing from a 107 rod.
To this day, I believe the best tune I've achieved is on a 225 Rapido, that gave higher torque figures than Hp, and rode like a dream, topping out at 70mph.
If you want it to do 65 like a train it will. If you want it to do 80 like a sprinter, it will. You chose.

B-Race Tuning wrote:The end result should be that it rides how you want it to. End of. A Rapido Classic has good port timings all round provided you're using the full skirt piston. Depending on final ride choice pretty much any combination of porting can be achieved, even without changing from a 107 rod.
To this day, I believe the best tune I've achieved is on a 225 Rapido, that gave higher torque figures than Hp, and rode like a dream, topping out at 70mph.
If you want it to do 65 like a train it will. If you want it to do 80 like a sprinter, it will. You chose.

How did you accomplish your "best tune...rode like a dream" Rapido tune?

Guess I am curious to see if it is worth the hastle to change out the con rod in order to smooth it out.

Last winter I did change the front sprocket so it now has a 4.9 ratio, as per AF Rayspeeds recommendation, which helped greatly.
Also switched to a 28mm delly, this also helped.

LI225Canada wrote:People often mention that they use a longer con rod with the Rapido Classic kit, 115/116mm, so as to tame the timing and have it run smoother.
I am just over half way through break-in and can see (feel) the need to smooth it out eventually.

Is the end goal to make it so the top of the piston (Not the crown) reaches the top edge of the cylinder then you know that everything else will be as it should?

No, it is to achieve a less acute angle between the big-end and the small-end bearings, and therefore reduce side trust forces between the two (and cylinder + piston as a result). Comprende?

Yanker wrote:

LI225Canada wrote:People often mention that they use a longer con rod with the Rapido Classic kit, 115/116mm, so as to tame the timing and have it run smoother.
I am just over half way through break-in and can see (feel) the need to smooth it out eventually.

Is the end goal to make it so the top of the piston (Not the crown) reaches the top edge of the cylinder then you know that everything else will be as it should?

No, it is to achieve a less acute angle between the big-end and the small-end bearings, and therefore reduce side trust forces between the two (and cylinder + piston as a result). Comprende?

That makes total sense, thx for the clarity.