Rejetting for High Comp?

[mck08]

G'day from downunder.

 

I've been running this setup for 12 mths now.

FMF Fatties,K&N pod in stock airbox lid on, snorkel removed, +4 timimg 98 octane fuel, 32:1 mix,Boost bottle, 310 mains, 30 pilots, needle all the way down, Top end good, bottom end burbly and nearly missfire sounding - it feels rich to me. Sea level

 

Anyway, I melted a piston on the beach ( turns out I had torn carby boots at boost bottle )and so I have some Nasura High compression, High performance pistons(+8HP apparently!)coming and the manufacturer recommends jetting up 1-2 sizes on the main.

 

Oh and its now had a basic port job cleanup.

 

My question is Do I need to go up on main jet size and if so to what?

 

If I go larger on main, will it make my already average low speed performance worse or am I missing something here?

 

Any help would be great.

 

Perth Australia

[sleeper06]

I have had bikes with that exact set up.With the lid on at sea level I ran 240 main ,27.5 pilots, stock needles jacked to the rich side,with a clean-up port 260s on the main,If you take the lid off 280s-290s on the main.To me you sound rich all over,make sure you pressure test the bike or else you will chase your tail with jetting,If you raised port height let me know I have jetting cards filed for those pipes in many set-ups