GF racing sell HRC style short air stacks, do these replace the centre stacks so the air box have 4 short stacks? And what is the advantage? I'm needing to sort my fueling out as I have 112 factory pro jets on GF pipes, standard air box with foam filter in place of paper, the bike doesn't pull as hard as I'd like but the top end seems fine, I do think it is running rich and I can't really afford dyno time, any pointers? Oh it's also the early (A) carbs, recent engine rebuild so all valves reground and shimmed. If anyone near Bristol area fancies a nosey, let me know

Hi
Just fitted the trumpets, foam filter and jets which i believe were the same as you have on mine at the weekend. GF trumpets go on the outside and the standard outside trumpets replace the long middle ones. i just run a race can on mine at the moment but it feels a lot stronger through midrange, so i am very pleased.
Cheers

What are the difference with gf trumpets or are they similar to the smaller standard ones,?

They are a little smaller than the outside small ones they replaced

I don't suppose you could measure the difference as I'm thinking of getting some made of nylon

They need to be made of a flexible material so you can get them through the base plate and in the right position.

The rubber also forms a seal between the carb and the underside of the plate which stops air from entering the carb from underneath the airbox.

I can't see nylon being any good to be honest.

To be honest I haven't had a good look at how they are fitted, I know that nc29 are ally and some like zxr400 rubber stacks can be replaced with fibreglass or nylon ones, I might just try standard short ones if I can find any

Mine are now fitted unfortunately, but they wernt that expensive from GF, if you look on his website they will be on there with a price
cheers

You could always cut down your long ones if you're happy to sacrifice them. Don't expect to notice the difference though.