carbs
 

anyone every try an off road card on a onroad car and what the differance would b ?

as long as the venturi size is the same, I wouldn't think there would be any difference in performance if they are both slide carbs.

In most cases, I would rather go the other way and run an onroad carb on an offroad car. Except for Nova, OS and a rare few others, most carbs on most offroad motors are junk.

i was comparing the 2 novarossi carbs both slide carbs brand new i see the low speed needle that goes across the inside intake hole on the off road is thinner and longer and when throttle is fully open that neddle does not come out of the high speed neddle hole all the way like the onroad neddle which is shorter and fatter and when open all the way is 50% across the intake hole.
i would b testing this instead of asking but here in ny we still got 2 feet of snow on the ground!!! lol i heard it comes down to a tuning issue that the off road carbs dont tune as good as the onroad cause they dont really have to cause an off road clutch is not as precise as an onroad...

I hear a lot of offroad guys don't like the long needle nova carb, they all went back to the short needle.

I really liked an OS long needle carb in onroad though.

Basically and to explain it simpler, the long needle gives a smoother more gradual acceleration needed in offroad, while the shorter blunt needle gives a more agressive sudden acceleration kind of a on-off situation more according to on road driving style.

On the tuning issue i would say the longer needle will give you a more fine tuning possibilty an less sensitive comparede to the short needle on the on-road carb.

AFM

Short & Long interchangeable Needles
 

Are Novarossi carburetor needles interchangeable?

I would say that if we are talking about carbs that have the so wrongly called mid-range needle, which is actually the main jet, yes, because you have to change both in pairs, that is the low speed needle with the main jet, because the taper of both are matched.

If we are talking about carbs with fixed main jet, i would say no, becuse changing only the low speed needle wouldn't match the taper of the main jet.

AFM

Production wise I would say the hole in the main jet is a standard. The shape of te needle is making the characteristic, some Picco engines do come with 3 needles......

The shape of the needle is not only making the characteristic. It has also have to match with the speed of the servo and the reaction of the revs of the engine.

maybe the long needle might good a good thing for an onroad track without traction when u have a really banging clutch it might make less tire spin..

I like the long needle for whatever the case. At least in principle it makes more sense, the long needle will not suddenly open the jet at 1/4 or 1/2 throttle, giving the engine a better chance of reving up a bit before the full gulp of fuel is released and thus giving the engine(glow plug) a better chance to handle it. It keeps the engine more in the lean spot while opening the barrel and reving up, so it should give more instant power/torque.

Although it may require a little bit of a different tune...

xe

I would prefer a long needle too, in theory it is better, but practise might show to be worse.
Like people said before, the longer needle makes a more gradual change and the sensitivity of changes would be a lot smaller than a short fat needle.
It makes sense for offroads to have the longer needle, they more or less vary the throttle in midrange a lot compared to onroad - either full throttle or varying somewhere close to no throttle.