Hi everyone,

Now we already have a thread for general fitment and queries on bike carb conversions, and also one listing various setups. They are also worth a read. The large FAQ thread has a lot of useful info too, links to the other thread can be found in a pinned thread at the top of the FAQ.

I have put this thread together to list information, hints and tips and allow people to ask about setting up their carbs.

I will update in due course, and write a bit of a guide and hopefully some others will input to, however for now I have just copied a few posts over from the setup thread.

Key bit of info for setup quoted here, the right sized carbs for the job

Heres the way to calculate the correct carb sizes for the job,

Venture size = √ (0.6 x Inlet valve Diameter^2 x Number of inlet valves / 0.85)

just to let you know 0.6 is an estimated flow coefficient, i would expect it to be that being ported and polished,,, may be 0.5 if not,, and if you

think you have an F1 head which you wont 0.7

the 0.85 is effective area dont worry about the its just a percent!

For top end power round up to the nearest mm

For bottom end round down 2 mm

for example 6n 16v

√ 0.6 x 29.5^2 x 2 / 0.85 = 35.05mm

Where to start. I've read through the various carb threads and setups but no one seems to mention needles. My problem is anything over 6000 goes dangerous lean and runs rich under 3000 which the engine can deal with but it cannot deal with the lean part at the very top I have found this out the hard way. It's running a 160 main which is supplying enough fuel but when it get to that part of the rev range the needle is limiting it to how much fuel it's allowing through. So my question is how do u guys get around this. Ideally I would need different shape needles something bigger up top so it doesn't run so rich down low then something smaller at the bottom so it can allow the fuel through to be safe to rev higher, even with shimming the needles it doesn't help much as it still runs rich at the lower revs. Know I have hunted around for needles and my searches bring up nothing. My options is to very carefully machine down the thickness at the very bottom by fractions. However getting all the needles the same is near on impossible. So can anyone point me in the direction of a place that sells different needles are any ideas on ways to get it richer at the very top of the rev range