Aprillia RS125 smallie engine

[Rosi-C9]

Smallframes are not my buisiness but this might be interesting:
40 HP at the backwheel.

http://www.youtube.com/watch?v=2iij325r ... re=channel

dyno scene: Exhaust control by pulling the break lever

[Wayne Miller]

exhaust wise, consider using the std aprillia one,just adapt it to fit and give it a longer reflective cone to suit your four speed box........also a slightly longer down pipe....
just an idea ,and if you could do this your self it could save you £100s
one off pipes can be very expensive,would not be suprised if you,ve had quotes of £500 plus.

I bought a standard exhaust today so I just need to find some software and take a few measurements of exhaust and transfer timings as well as the standard exhaust measurements
One question though Sean, how the fook do you measure exhaust port area?
and if I input this data into a program Im guessing it will show me the required sizes/angles that I require but how do I adjust these for 6 / 4 gears ?

Hmmmm, I guess that was two questions not one

PS this question is directed to anyone not just Sean

[J1MS]

You need to do a rubbing of the exhaust port & transfers to get an accurate cm squared measurement, wrap your tracing/rubbing of the ports around a piston of the same size and use dividers to transfer the chord of the port to graph paper this will give an accurate exhaust port measurement, but the transfers enter at an angle, you will need to square that angle to the bore to get a measurement that means anything, otherwise the transfers appear larger than they are in reality.

DO NOT INCLUDE ANY PORTION OF THE EXHAUST & TRANSFER PORTS THAT ARE COVERED BY THE PISTON AT BDC. as this will also give over large port areas that will mess up your results.

[Wayne Miller]

Hi Jims,

Thanks for the reply mate,

So if Im getting this right to get the port area I take the widths from here?

Excuse the rough drawings



Once I have the correct width and the height what maths do I do to get the port areas?

[J1MS]

I usually crunch the numbers using A G Bells two stroke tuning book formulas, but there's probably easier ways... But transferring the dimensions with dividers to graph paper, this gives you squares to count... all the whole squares = one, then each part square, just count as 0.5. If you use 1mm squared graph paper the final areas will be very close to right...
If you can think of a better easier & more accurate way then let me know.

Youve got the diagram spot on, thats the correct way.

[Wayne Miller]

A pic of the new packer/adapter plate



Just needs matching to the transfers on the cylinder and then scooping some meat out of the casings

[twin]

looks good ,
i put a rs125 lump in a lammy frame,
and cut and shut the rs pipe ,
when i have done my twin autos,T,D,R, made some pipes for me,
a mate has just had them do one for his LD auto,
and i think it was about £300 all in,not bad for a one off,

[Wayne Miller]

T,D,R, made some pipes for me,
a mate has just had them do one for his LD auto,
and i think it was about £300 all in,not bad for a one off,

TDR? Have you got a link or contact details?

Cheers

[MrG68]

tdr just done a very well made and brilkliant fit pipe for me drag too,


01933443430

[Wayne Miller]

Cheers, Ive just googled there number '01933443430' and found out that there in Wellingborough.
I'll pop over and have a word with them soon