You have a 73a sp correct? - Your petcock should face backwards, and the fuel line passes through the gap in the middle of the airbox to the fuel inlet to the carb, which should be pointing up. Quite a short run of hose.
It;s a real PITA getting the airbox on and off on the 73, but I can do it with just a long reach phillips. (maybe I'm just super human!) I did eventually resort to pods though!

I've re-routed. Took a couple of goes to work out where is right. When it was wrong it was pretty obvious. I haven't shortened the fuel line yet, so it does go around the top of airbox a little but it's all horizontal at that point.

I tried to tighten the centre two clips but it was absolutely impossible with the phillips bolts. None of my screwdrivers are thin enough in their shank/shaft. So I switched the bolts on the clips to cap head. Bloody doddle for me now!!!!! 3mm (I think) alan key fits in there a treat :) So that's my top tip of the day!!!!! But may only work well for a numpty like me. Normal people may find the phillips is easier/easy enough.

Cheers,
Glen.

did the rerouting fix your fueling issue?

I'll let you know 120miles time.......

Although I ripped out the air silencer/horn/restrictor from the airbox when I rerouted. But I've yet to re-jet and it runs SOOOOOO lean now. Will not pull above 5000. So those 120miles may take me a little longer than normal.

Without trying to sound boring! You need the intake horn, as it correctly meters the air for your bike. It will run worse, and also too lean and subsequently lose power. Can you not re-install it. You are meant to re-use it when you replace the air filter.
If you have a race can this will also lean the mixture off further.

I know the horn can add to the helmholtz effect but that side of the filter I'm unconvinced by that being its primary function.
It feels, seat of pants, that it is now pulling way more air and is subsequently running quite lean. I can sling it on the dyno to find out for sure but it screams lean to me. So bigger jets seems the way forward. Actually, its the needles that are lean at the 5k that I mention but hey, it's the same hole.
It is my intention to make a few more ponies, not to keep original.

Maybe I could follow your route with the pods. But as I've already got the SP box I'll stick with for now.

Cheers,
Glen.

HI Glen, no you're right it deffo is mega lean. This is partly caused by fuel stand-off, due to there being no back pressure left in the airbox. The back pressure helps keep the mixture in the carb at lower revs.
I found out you have to use pods with a backing plate to reflect the reverted fuel back into the carb, otherwise it won't rev past 5 or so grand. If you use foam pods with cv's, you may as well forget it on the gsxr400.

I've been toying with a slightly larger intake for the std sp airbox, and re-jetting. This should then make more top end power than pods, and minimise the classic cv/pod flat spot when you crack open the throttle. I practiced this with fair success on the Aprilia RS250.
I find the pods are now too loud for any sustained ride. I found it good fun for a bit though!

Well it's "fixed" in as much as once I connected the vac port for the petcock to cylinder one it runs on reserve. It's looking VERY likely I have tight inlet valve clearances on cylinder two. Cam cover coming off this evening.......