Best PIPE

McScooterson

PSEUDO TUNING
I have a slightly tuned MHR-R, and am getting a Polini Evo.

I am currently running a Yasuni c16, and was wondering if there was a better pipe for running both of these motors.

I looked at the dyno reports over on S-A, and it looks like the R1200 would be good for both.

Is that correct?
 
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Are you getting your evo tuned?
If its stock I would just keep the C16 because its a verry good combination!
Otherwise if you are getting it tuned you should choose a higher revving exaust and (get) your cilinder tuned to those specs.
It also depends about what evo we're talking about, is it the one with the butterfly exaust port?
 
It is for a A/C horizontal minarelli. 12mm pin. I am very happy with my yasuni on the replica, but I was concerned it might not be enough for the EVO after looking at the S-A dyno for the MHR Team kit.

I am keeping the EVO stock, so I'm glad to hear it will work well with my pipe.
 
the C16 would work fine with an EVO AC kit, it's got low port timings for a racing cilinder, if you set the squish to 0,60mm you'll get 186/129 port duration. it is like a midrace cilinder only with a bigger port area for a given duration.

i don't see any reason why you are having problems with the MHR Rep but probably you haven't touched the transfer ports which are very low for the pipe you are using (not enough time/area), i ported an MHR R AC to 185/130/126 & it uses an MHR copy pipe & it runs very well with a 24mm OKO carb, it can keep up with a tuned 90cc scooter & has a topspeed of 130kmh, not bad for a street scooter.
 
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I haven't really touched the cylinder walls. I raised the main exhaust port ~1mm, and that is it.

I matched this cylinder to the cases, and the cases to the cylinder.

I matched the cylinder opening to the same size as my Yasuni flange.

And I have my squish at ~1m. That was brought down from almost 2.5mm.:(
 
I haven't really touched the cylinder walls. I raised the main exhaust port ~1mm, and that is it.

I matched this cylinder to the cases, and the cases to the cylinder.

I matched the cylinder opening to the same size as my Yasuni flange.

And I have my squish at ~1m. That was brought down from almost 2.5mm.:(

i see but you didn't raise the transfer ports so you are running out of breath at high rpms b'coz of the short transfer port timings, at least you should try raising the primary transfer port (closest to the exhaust port) by 0,50 for starters & see how it does.

the MHR R has a lot of potential if you port it correctly but with an EVO AC kit you don't need much work done to it, just match the cilinder ports to the cases & you're all set.
 
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