Measuring carby's?

[TygerTung]

When you measure a carby to find out side it is?, where exactly do you measure it from?

I'm gonna go get a bigger carb for my CG for maxumum performance, but where on it do you measure the throat? It doesn't seem very round, as it's a slide carby, not like those funny butterfly venturi ones like in those bloody cages!

Cheers,

Sam

[MSTRS:Me]

When you measure a carby to find out side it is?, where exactly do you measure it from?

I'm gonna go get a bigger carb for my CG for maxumum performance, but where on it do you measure the throat? It doesn't seem very round, as it's a slide carby, not like those funny butterfly venturi ones like in those bloody cages!

Cheers,

Sam

You measure the throat diameter on the engine side. Bigger will only increase performance if you open up the inlet port on the head to correspond.

[Ixion]

And maybe not even then

[Motu]

You measure the throat dia where it bolts to the head - but some Honda's don't have a round bore in the carb,it's an oval.Guess you could guess on the average dia.....

[Sniper]

You measure the throat dia where it bolts to the head - but some Honda's don't have a round bore in the carb,it's an oval.Guess you could guess on the average dia.....

Use a bit of string to measure around the oval. The diameter should be half the length of the string. (Sound about right?)

[MSTRS:Me]

Use a bit of string to measure around the oval. The diameter should be half the length of the string. (Sound about right?)

How'd you calculate distance in your last job and is that why you longer do that? You've come up with half the circumference

[Deviant Esq]

LOL, nice.

Circumference = 2πR = πD. The diamater of a circle is C / π. And the symbol for pi (π) sux in the standard KB font. LOL

[Motu]

If it's an oval you'd have to measure area and compare that to the area of a circle...or just guess.Put a carb off a bigger Honda single on - XR125/185/200.They may still be oval...but a bigger oval,and that's all we are after is it not?

[TygerTung]

Yeah I got a honda XR200 carby for it today, bolts on, sort of, it's way bigger and doesn't run properly, I'm gonna have another look at it tommorow, but I think it should go pretty good, I need those inlet manifold blocks though, the CG ones are too small and they don't even go over the rubber ring which seals against the blocks.

It's all good fun though.