Airboxes R vs SP

[casal-fan]

Looking on the old forums, there are a lot of references, to the different airboxes. Some pics aren´t there anymore wich is a shame, but nevertheless references, are.

This is imo, quite an important issue specially on road going bikes, and for people as myself that don´t fully understand the meaning of an airbox, or better, the consequences of modifying a gearbox.

Common practice seems to be to "upgrade" the left hand cylinder lid to SP spec, and by this get rid of the possible airflow obstacle that the tapered intake tube has. But this got me thinking...
The right hand cylinder airbox also has a "restrictor" device inthe tube that connects the vertical tube to the airbox body... and this is, in most cases kept by the people modifying airboxes.
When there is air flow involved caused by different pressures involved, intake diameters, lenghts etc play a major role imo, and I´m a bit scared that just cutting away would really be to no usefull effect.
There is of course the side that the upper lid was modified for 1995, while the right hand cylinder airbox was not...

I stod ready with a heated knife blade , ready to cut the snorkel on the upper lidt, but then I thought I´d better writte something here first, and hope for some opinions to show up.

Does someone remember if in the past someone tested upper lid "mod" vs standart?
Or some good opinions on this subject would be great.

Rui

[jt3xv]

ramair pod filters are supposed to be ok on all 3xv's, putting em on my r with martin 77 ported barrels n dfr chambers ,sugo plugs instead of boost bottles ,n all heating pipes removed from carbs,cheap too mine were £30 for a pair delivered

[jcsnook]

Cut it...

Before:



After:

[eyrey1]

i cut mine and kept the bit ,but never try'd it ! ive gone to pod filters as well
£35 for a pair they look pretty good ! not used yet as its still in bits !
i will post something once its dyno'd

[Kingy38]

i've modded both the upper & lower airboxes on my 3XV,i'll post the pics soon as i find where i put them!! 

[41juergen]

Hi Rui,
funny, I thought the same! If we want to stick with the air boxes (instead using the pods which I do eg. on my RZ and they work perfect) I think the mod for the upper box is clear. But I fully agree (if I understand your point correct  ) the rubber hose or connection between the lower boxes will still restrict the air flow (assuming we run a 32 or even more worse than with the 36mm flat slides)! I still had a first look how to change that but still need some time as priorities are set different at the moment. Looking forward for other opinions, EEKNOWS    ?
Juergen

[Paul]

excuse me for butting in here
what are you trying to achieve?
or is it legistrature that is influincing your decision
are you looking to open it up and roar around?
most race bikes use nothing behind the carbs
i use mesh on TZ and pods on MC21 (and 3XV - added later), mainly because im scared of sucking stones
my 3XV would only run without airboxes after derestricting motor, custom pipes, Ignitech CDI and sugo carbs
if you are eventually going to come to this point over time, dont cut your airboxes as you have a scanario where it'll run as standard and you can always go back there for MOT/COR/testing.
are you running the little 28's?
for me i always start at what the end goal must be and work backwards, then it is clear to me what i can cut, hack or sell or throw away
(i have SP and std boxes for sale in for-sale section by the way)
else you just end up playing with jetting and running more risk of seizing/damage with every small change you make

[casal-fan]

Thank you all for the feedback.
Paul, I totally agree with you about setting a goal, and define where you want to go before you start going.
For the rest, just trying to get some input on something not yet discussed before (?), the little rubber tube connecting the upright tube that feeds the right cylinder rearbox.

Juergen, me too looking forward to see how peole tackled this.

Kingy, looking forward to see the pics. Running 28mm carbs? Or did you try it with 28mm carbs?
By the way, congrats with the 2012 results.

Good pic jc, thanks.

[Warwick]

When using the 28s, the only airbox mods I made was to use the freer flowing SP top airbox lid. It didn't look like the lower airbox link tube was quite as restrictive of flow, so I left that alone. It seemed to work pretty well. I ran the SP upper box lid from the off, but a friend was using an R upper lid on a very similar set-up to mine. Borrowing the SP top box lid gave him about 1bhp at the top end in back to back testing so he bought one. I made some other changes to the carburation (needles and nozzles) after initial set-up with the 28s and it seemed to give some improvements to the power feel over the initial set-up, but I never got round to dynoing it again like that as I went over to the bigger carbs before I had the chance to get back on the rig.

Might be best to get a base reading with the boxes completely stock and then try mods though so that you can properly assess their effectiveness?  The 28s seem quite sensitive to airbox mods though, so you may have to jet any mods in a bit to get it working well after after any airbox mods .

[EEKNOWS]

Looking forward for other opinions, EEKNOWS    ?
Juergen

Sure thing here is what happened when we removed the 'restrictive' snorkel from a Aprilia RS 125

[Warwick]

...you may have to jet any mods in a bit to get it working well after after any airbox mods .

[EEKNOWS]

was rejetted got 2HP lost back but using more fuel. Juice not worth the squeeze on that one.

[Neal]

So it was worse ?

I don't want to start an argument , but will the 3xv behave the same way if the airboxes are changed / modified etc ?

[Russ B]

Probably not that much of a comparison, but still a fairly highly strung 2T, albeit a single........My Cagiva Mito 125's run rubbish in the mid range when the snorkels are removed or when running a pod filter, (even with re-jetting) they also usually drop a couple of peak hp from graphs I have seen (which is quite alot as they are not that powerfull anyway.lol circa 32-34 quoted  in the manuals depending on model). I always run airbox's with the correct snorkel type on mine & they run perfect.(there are 3 fpwr types depending on spec).  I see it as Cagiva new what they were doing with the airbox & snorkel design 

[maccas]

Hi guys,

I'll give my take on the airboxes.

I'm running the right hand box as stock for a 92 RS model with SPR airbox to carb rubbers.

I'm running the left hand box with an early SP airbox lid and SPR airbox to carb rubbers.

Early SP 36mm carbs.

I've had fairly good results with the airboxes as above. The intake to the upper airbox is larger compared to the one for the lower cylinder. I'm having to run 3 jet sizes larger on the left hand side compared to the right cylinder and even then the right cylinder is running richer than the left.

It is unclear as yet whether the airboxes are what is causing my bike to drop off so sharply after peak but that will be investigated next time I get it on the dyno.

One test we did do last time was to remove the air filter element from the right hand box and compare that to a run with the air filter element fitted. The gas analyser showed that the mixture went leaner with the filter removed compared to when it was fitted. That tells me that the snorkel on the airbox WAS NOT governing the airflow into the right hand cylinder. If it was, the mixture wouldn't have changed. Yes I know people say the gas analysers are not accurate, I probably agree, however it was the relative change in gas analyser reading that was interesting. It went from 12.5:1 to 13.5:1 which is a big change.

I'm sticking with the airboxes until they become the limiting factor, as yet I don't think I have reached that point.

Dan