Hi Guys,

Just wondering if anybody could give me advice to setting up my bike carbs properly? (believe that they are zxr900's).

I don't think that the air/fuel mixture is quite right at the moment.

Cheers

Best way is to take it to Bogg Brothers.

The best way to do it yourself is get a wideband air fuel ratio [afr] meter and be prepared to do some messing about with needle positions and jet changes.

The only mixture you can adjust with a screw is the idle mixture.

Taking it to Bogg Bros will be a lot easier though.

Stu

[Edited on 4/4/11 by whitestu]

It's very hard to say what you need to do as you have not said what engine you have fitted them too
also what mod ie cam pistons has it had a re bore any head work etc

as above the only way / safe way is to set it up on a rolling road and the best people are Bogg Brothers
Jacko

As a basic set up this may help?
Assuming the timing is already correctly set start off by setting the idle screws all the same 2 ½ -3 turns out, then balance the carbs when it is running either with a flow meter or listening to the sound of the suck with a bit of rubber hose. One of the carbs is the master, probably the one with the cable connected so get the next carb in the line sucking the same amount by adjusting the throttle linkage screws, then the next and so on. You will have to adjust the idle speed as you do this as the revs will be going up and down. This will give you a good starting point, if there is a lot of spitting back through the carbs at idle and slight throttle opening or overrun then the idle mixture needs richening. If the exhaust is sooty after normal driving then perhaps the needles could be lowered to lean the mixture if it is sooty after a real thrashing then the mains are probably too big. Conversely if the exhaust is very pale and it struggles under load then the needles need raising and possibly bigger mains, but without a rolling road session it will be just trial and error, do runs then check plug colours to get an idea of what is going on.

[Edited on 4/4/11 by Dingz]

Just be aware of the dangers of the mixture getting weak at high rpm

It really needs something to tell you what the mixture is doing across the rev range...........