clam shell airbox

[neil p]

will this fit straight on, in place of the newer square box ?

it looks like it will pass a lot more air !

 

[Kenny]

Sort of fits...but won't pass anymore air..looks cool on bob tails etc though

 

[Rob Farmer]

They do pass more air, I have one on my R100PD to clean up the air/fuel ratio at the top end. The only downside is an increase in induction roar which I presume the later airbox was intended to remove. You also need the starter motor cover to go with it, this has a vent on top for air intake. It's also a good idea to fit the small cover and spring clip onto the back of the starter motor to prevent clutch dust and warm air being drawn through your carbs.

when I put the bike on the dyno it was obvious that the standard airbox doesn't work properly at high RPM. I had the standard jetting fitted but the bike constantly ran too rich at the top end. There are only a limited amount of mains jets available and they come in too big an increment to set the jetting accurately so I tried alternative airboxes to bring it in line.

Interestingly if you put 32mm equipped bikes on the dyno the jetting works really well with the standard airbox.

I use Hilltop motorcycles in Earl Shilton for dyno tuning. He has a great reputation for unleashing the 1200's as well.

You can just see the airbox here -

There are different types of clamshells you need the RS one with the perforated holes in the back of the box. There are also different castings for breather pipes. There's a clamp that bolts to the top of the gearbox you will need as well as a small spring clip to secure the left hand shell.

The clamshell you need looks like this from the back. The non sport bikes had a solid unit and just breath through the starter motor cover.

Of course you could leave your bike alone and just ride it If you get on the slippery tuning slope you really need some dyno time to make sure you're not screwing things up. The best thing to do is take your bike for a dyno run with it as it is. Fit a genuine air filter - some of the aftermarket ones are terrible for air flow. I had one that swelled up, strangling the engine, when it got damp

 

[neil p]

thanks Rob, good info........

its a R80 ,so 32mm carbs , so perhaps i will leave well alone.

i am using a K&N, mainly so i can clean and re-use, instead of just chucking the paper ones.................

 

[Kenny]

Seriously, you can't beat a genuine OE air filter