flat spot (more like a black hole??)

[lewis]

My bikes together (gsxr 600 with 750 in it) and i took it for a whirl. Increase revs slowly and it runs sweet all the way to limiter, start below 3000rpm, nail it and it takes off, hits 4500rpm and dies for a second or two, then coughs and splutters all the way through. I was thinking its a fuel problem, engine / carbys are stock. Filter is K&N from my 600, stock headers and shorty d&d pipe. any ideas? It seemes to be getting better as i ride it a bit more could it be dirty carbs or the fact the engine has been sitting for so long? (over 16 months)
Any help appreciated,
cheers, lew

[Issues]

sounds like a fuel restriction, cant supply fuel rapidly. Maybe dirty fuel filter, shit in fuel lines ect.

[Docktor]

Might be a touch lean with ya K&N hangin off it. Restrict the air with some tape wrapped around it and see what happens, failing that lets find the dude who shit in ya fuel lines :). Bet he is only little and we could bash him.... maybe. Bedtime and no more wackyweedindeed.

[EFE 1230]

This is SRAD 600/750? A k&n won't give a flat spot with stock carbs as I have one in my 600 + full Yoshi (or stock can), but a bmc will with stock can (but not full yoshi)!!. A guy I knew a few years ago had a 750 with flatsides + adapters to fit stock airbox he wanted to open up air intake opening in the airbox so bought another from wreckers for a 600 and I seem to remember he said something about the opening being smaller than a 750.Not sure if this could cause the problem you have but easily fixed if you have a dremmel!!

[Rocket]

I heard somewhere that those SRAD's have some sort of fuel pump to keep fuel flow up to the carbs because of the layover engine arrangement or something.
I think it's a vacuum operated bizzo, might be worth a look.

600 bodies are different that 750. the throttle position sensor is an issue.Booster knows these carbs

[Booster]

I know its easier to replace them with efi ;)

i'd look at the fuel tap, suck on the vac signal line and make sure it flows (should if its running at all) most likely fuel pump/internal filter, run the outlet hose to a container and externaly power the pump, should be at least 5cc/hp/min
so if you can't get at least 600cc in a min you have a problem
(be careful with sparks and fuel...)

[pt]

what airbox are ya using? sounds like it's running lean to me. popping and farting worse on steady throttle? check that the airbox is reasonably sealed(lid, connection to carbs, filter).

if this is all ok then i would head to the TPS. and then move straight to EFI like booster said. i spent so much time and then cash trying to get mine going ok....

EDIT: oh and make sure you check the vacuum hose ffrom the carbs to the fuel pump (goes in horizontally). but i reckon youd probably have that down pat.