Ditching the airbox?

[Coyote]

I was reading up on the TYGA site about preparing your MC21 for track days (I do relise I have a MC22 4 stroke, but I was interested in reading it anyway). I came across this which I thought was interesting:

Airbox

If it's going to be a track only bike then you may as well junk the airbox. It does nothing but restrict the high speed airflow. Open carbs are the way forward.

I was wondering if it was a good idea to do this to my CBR? Is it at all worth it, will it only cause trouble with shit geting into the engine and do streetstock rules allow for this?

http://tyga-performance.com/pages/MC21_tuning.php

[TwoSeven]

If you ditch the airbox on an MC22 you'll go backwards. The principle design behind the engine was that it required still dead air, filtered from dust.

Also the airbox is resonance tuned to the engine, so unless you have another method of duplicating that, you'll lose power as well (its why the airbox is the shape it is).

About the only thing you could really do with the bike on the cheap is add a ram air system in - but you'll need to pressurize the carbs as well.

[Two Smoker]

I was reading up on the TYGA site about preparing your MC21 for track days (I do relise I have a MC22 4 stroke, but I was interested in reading it anyway). I came across this which I thought was interesting:

I was wondering if it was a good idea to do this to my CBR? Is it at all worth it, will it only cause trouble with shit geting into the engine and do streetstock rules allow for this?

http://tyga-performance.com/pages/MC21_tuning.php

waste of time and will cause problems... best bet, stick on sticky tyres (GPR-70's) and work at riding fast with good lines... ive got virtually no mods to my ZXR other than a pipe and headers and a slightly modified rear shock...

[Coyote]

About the only thing you could really do with the bike on the cheap is add a ram air system in - but you'll need to pressurize the carbs as well.

Sounds interesting. How do you pressurize the carbs though? It sounds like work thats far too advanced for me

[Two Smoker]

Sounds interesting. How do you pressurize the carbs though? It sounds like work thats far too advanced for me

yes, advanced and a waste of time on a SS250 bike that has strict rules...

[TwoSeven]

Sounds interesting. How do you pressurize the carbs though? It sounds like work thats far too advanced for me

Have a look at the ram air design on the cbr600 (1995 onwards). Also kehin do a conversion kit for their FCR carbs for the 600. See if you can find a pic for it. Basically you'll have to make the same things for your bike.

[Ivan]

streetstock wont allow it

[Coyote]

streetstock wont allow it

streetstock don't have to know

You aren't allowed a different sprocket in the rear right? I need to replace the chain and sprocket as the originals are still on it and have suffered their 20,000k life. I was going to get a bigger sprocket as this improves acceleration doesn't it? I don't reach top speed at all so I wouldn't be sacrificing much

[Ivan]

Why do you need to cheat it wrecks the class I think that is why they call it Street stock so the bikes are standered not modified

[Coyote]

Im a vic club commitee member so now I know.

Bah, foiled again!

So you can tell me about the rear sprocket then right? I need to replace it with one with the same amount of teeth on it don't I?

[TwoSeven]

Its a 17/52 425 standard (check that chain pitch I cant remember exactly).

[speights_bud]

Have had the suggestion of removing the air filter from my A100. The bike runs pretty sweet with it in at the moment and was just wondering if it should be left as is?

[Coyote]

http://www.cr-x.org/cbr250/forum/top...49&whichpage=1

How illegal is this for streetstock? Would it be allowed for the F3 class then?

Allthough,doing all this willl be way out of my league at this stage

[TwoSeven]

I was just thinking, if you did remove the airbox, then you need to go for a stage 3 or 7 dynojet tune. In your case a stage III.

This type of tune uses longer velocity stacks to reduce the intake turbulence and will also normally have an individual dust filter over the end (i'd suggest this). Often you will hear them called pod filters.

You'll need to try some different length stacks to find out which ones work as they are different for each bikes requirements.

You'll need to completely rejet the bike (all jets and needles) which will be expensive and also set it up on the dyno. While you will get more power (on the 250) you wont have any low down power (so forget trying to accelerate out of corners).

ps. Why the fek is it that aussie mechanics cant use the proper terms for things. I mean who the heck calls a velocity stack an 'air funnel' anyhow (the cibby manual is written by aussies).

[FROSTY:Me]

dude my advice plain and simple. Dont fuck with it.If you wanna go fast invest in tyres and suspension and learn how to ride fast.
I wasted a whole frigging season learning that lesson