It seems that with the advent of the 1100 motors, performance 900 builds are becoming a thing of the past.
When I joined the forum, hot 900 builds were common with people fitting hi comp pistons, big bore kits, cams, bigger valves, porting and light internals.

Everyone's moved on mate!






It's all about the hot 750's these days!

We'll have to finish the bloody thing so you can do a hot 750 thread.

Check out Yorkies builds. All three of them.

Hot 900's are too easy.

Real men build hot 750's.

Nibor would agree with you.

Yes he would 

I have finaly got time for my projekt. Frame painted in gold   Next in line is hom made struts to the shortened front mudguard, new bracket for seat/fueltank, cambelts, shorai battery under seatpan and so on.... Tank to be painted flat black...

I think this is a hot 900

 
What you doing to the motor?

Changed heads from W2 to V1, lightly homeported, keihin 41mm with as big K&N filters I could fit, lighten flyweel. Should be OK 

Very cool. How much weight you take off the flywheel? Which pods on the carbs?

Im offshore and dont have my papers here.... I think the flywheel ended on 1250grams, but not sure....
I bought K&N RX-4040-1



Thight fit, but its there

 What fun! Looks great!

Once I get back on the $$ saddle, I'll show you my 620/750 . . .

I am trying to make sure most of mine loose as much weight as possible.

Primary gears:



Butchered clutch cases:





Lightened adjustable cam wheels:



Alloy intakes:



And where possible a lightened fly wheel (this one is from my ST2 - 5kgs down to 1.3kgs):



Yorkie.