I was wondering?

[Mudflaps]

So I was talking to 'a guy' today who said my carb would produce more power out of the corners if I put my air box back on, instead of having a gauze over the mouth of it, as the carb would accept still air into it faster than moving air.

If this is true, and that is the first question, is it, Then what if instead of having still air pulled into the carb from inside an air box attached to the carb, you had a 'scoop' of some description pushing air to the carb mouth! Would this work?

Disclaimer
If it sounds like a rediculass thought/idea, please note that I don't know anything about engines at all, and was merely putting the guys comments through the grinder in my head

Can't think about much more than buckets at the mo...I have the bucket desease

[Sketchy_Racer]

Depends on each bike, but generally I've found that all my bikes have run much better when I have had a air box on.

My current bike won't run without it on now, it needs the static air.

Give it a try, it may work. Pod filters are just for posers....

[Mudflaps]

Yeah was originally looking at pod filters, but soon stopped. I might try a scoop and see what happens. Failing that, I'll chop the back off my air box and gauze it over.

[DELLORTO]

my fxr150 wont run with anything but a straight pod....

but now im working on my 2nd generation RAM air induction system..... so hopefullly my engine will run on that

[nudemetalz]

I put my pod filter on for the last meeting at Kaitoke which was wet, thinking it would keep the water out of my carb.
All that succeeded in doing was fill the pod with water and killing my power (well, what a Loncin has to begin with anyway !! ).

[mossy1200]

Yeah was originally looking at pod filters, but soon stopped. I might try a scoop and see what happens. Failing that, I'll chop the back off my air box and gauze it over.

CV carbs like airbox unless you modify the springs,air jets etc.Dont try ram air system ducts into cv carbs if thats what you have.

[CookMySock]

CV carbs like airbox unless [...]

Thats what I have always found too. My 650 won't go past 5,000rpm with no air box, but the 250 comet goes like stink with no air box on. Go figure..

Steve

[Mudflaps]

A cv carb? Not sure what this is but I prob don't have one. I have a standard ax100 carb which is I think 22mm? I was going to enlarge this though to a 28mm. I found the bike revved faster and ran faster without the air box on. I haven't re jetted yet.

[quallman1234]

I think the stock AX100 carb, is more like 20mm or below. Skunk would know. Its not very big at all.

Maybe im confused, but i believe CV carbs, relay on the vacuum to pull the slides up. Therefore the airbox and carb's have to be at the same pressure?

[pete376403]

Among (a lot of) other things, the air box reduces some of the intake noise.* An engine with an open carb is pretty noisy, which can sometimes be percieved as faster

* a chainsaw makes more noise from the intake than from the exhaust, according to a very skilled small engine mechanic I know

[StoneY]

Dunno if its the same thing - ive had an air box all along BUT the intake pipes were not connected to the inlets on my fairing (the GixxeR)
89$ later I had the two flanges that attach the intake pipes-

Bike now idles a lot smoother (or am I just imagining that) and seems to be able to pull longer than before- might be my imagination-

I guess the engineers test this shit at the factories

[mossy1200]

A cv carb? Not sure what this is but I prob don't have one. I have a standard ax100 carb which is I think 22mm? I was going to enlarge this though to a 28mm. I found the bike revved faster and ran faster without the air box on. I haven't re jetted yet.

cv carbs have (normally) a round top above slide that contains a bellows diaphram that lifts the slide.Non cv slides lift dirrectly from the throttle cable.
If you slide lifts with bike not going by turning throttle then its not cv.If it doesnt lift it will be cv.
If its not cv airbox shouldnt be needed but it will run lean if not rejetted and needle heights adjusted. lean is not good as engine temp increases and under load when riding it will loose power instead of make more even though it seems good when you rev it in neutral.

[mossy1200]

I have heard that rg250 flatslide carb is the altra mod for ax100 engine .You would need to check its not to large for you class of racing though.

[Mudflaps]

This is all great stuff thanks!

I have heard that rg250 flatslide carb is the altra mod for ax100 engine .You would need to check its not to large for you class of racing though.

I am racing f4 so think I'm allowed up to a 28mm carb?

I'll check out how big the rg250 carb is. It's all food for thought.

[F5 Dave]

Golly there is all sorts of advice flowing freely.

here are some reasonable - what I'm going to call facts;

1. you don't have a CV carb
2. your bike is 100cc so not restricted by carb size (as a 125 is to 24mm)
3. RG (28mm) will be fine, but you will have to find the right jets by experimentation else it will run worse (or worse seize)
4. depending on other modifications (ports & pipe) it may not be an advantage
5. always remember you have a 4 speed gearbox when making mods
6. I'd always mount a carb with rubber manifold if you change it
7. your mate's advice is pertinent for modern 4 strokes, your bike is neither
8. Cheap Pod filters are a restriction

& more anecdotaly,
9. I've made a few airboxes for my small 2 stroke race engines & have always ended up returning to open carb (albeit now with fully enclosed guards on 5 sides).