I'm really don't wanted to start this thread as I thought that I can figure out all by myself.
But I can't.
I hope someone can help me with right jetting.
Prehistory:
P150X not matching ports with DR 177 and Malossi cylinder head.
Rotary intake
SI 24/24 E drilled 2.5mm: AC 160 - BE3 -125 MJ and 55/160 idle.
Original air filter with drilled holes above jets
Mazzucchelli racing crankshaft 57mm stroke
22/68 primary
SIP Road 2 exhaust
SIP Touren flywheel 1.6 KG
SIP fast flow fuel tap.
I ride on that setup near 7000 miles short in town and really long hard runs on the mountain roads. Everything was fine, plug colour is right, I can easily hold 55-57 MPH for a really long time and temperature holds on 275-285º F.
Then I change exhaust for Polini Box and like it more than old despite I lost 2-3 miles of max speed. Still runs perfect without any other changes.
And then I put new SIP T5 air filter and Polini carb case cover. Run for a long stretch and I see that the temperature is growing faster and already at 50 MPH it easily reach 300ºF and continues grow up. Obviously jetting is too lean.
Then I change idle jet for 50/140 and main jet for 128. But it seems that it not helps really.
So its time to play with air corrector and mixer tube?
I don't understand anything at all, please help me understand. Maybe there is some links where I can read about SI carb settings? TIA.



Last edited by roland87 on Tue, 11 Apr 2023 10:31:59 +0000; edited 2 times