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Hole in airbox
Jubal - 21/4/07 at 06:35 PM

The hole in the airbox as per the pic below ended my day early at Elvington today. Under load it now won't pull more than 6k revs. Sat in the paddock it revs just fine.

What do you reckon has happened? And should I just replace it with a sausage filter?

Sorry if this is a numpty question but I'm no mechanic and am learning as I go. Rescued attachment smallairbox.JPG
Rescued attachment smallairbox.JPG


JoelP - 21/4/07 at 06:41 PM

maybe vibration, check that nowt has fallen into the carb! And i would use a sausage filter myself, maybe hooded if it doesnt sit nice out of the bonnet (ie air ducted to it)


David Jenkins - 21/4/07 at 06:43 PM

Didn't notice any backfires, did you?


PAUL FISHER - 21/4/07 at 07:00 PM

Hope you have not done any damage to the engine,bent any valves,those big bits of plastic pipe must have gone somewhere,it does not sound good that it won't rev over 6000rpm on track,I think it should not make that much difference to it reving out with the hole in the airbox,have you tried to driving it since with the airbox completely removed? to ensure there is no engine damage.


Jubal - 21/4/07 at 07:13 PM

Nope, no backfires. The piece that blew off lodged itself in the carb, it was one piece, nice clean break.

Cheers for the pointers. I'll get a sausage filter and chop a hole in the bonnet


Jubal - 21/4/07 at 07:19 PM

quote:
Originally posted by PAUL FISHER
Hope you have not done any damage to the engine,bent any valves,those big bits of plastic pipe must have gone somewhere,it does not sound good that it won't rev over 6000rpm on track,I think it should not make that much difference to it reving out with the hole in the airbox,have you tried to driving it since with the airbox completely removed? to ensure there is no engine damage.


Eurk I'll whip it off and check tomorrow before spending any cash on filters.


smart51 - 21/4/07 at 07:22 PM

Have a look at the airbox pictures in my photo archive. It flows air quite nicely. The plumbing bends that you have used have 90° corners and will strangle airflow.

A foam filter isn't too bad but can be noisy at full throttle.


Hellfire - 21/4/07 at 07:57 PM

As Chris says, I would be tempted to stick with the original airbox. Just remove the 90 degree extensions and fit the box back on. You may have to cut a hole in your bonnet though and fit a bonnet bulge but that's not too difficult. Better power and quieter too.

Phil


higgsti - 21/4/07 at 10:05 PM

i would say that because of the crack in the airbox your getting to much air in causing it not to rev(fuel air mixture too lean)if you do put sausage filter on you would need to re jet the carbs


tks - 21/4/07 at 11:09 PM

quote:
Originally posted by higgsti
i would say that because of the crack in the airbox your getting to much air in causing it not to rev(fuel air mixture too lean)if you do put sausage filter on you would need to re jet the carbs


yupsz thats it...
in fact i guess that for cilinder number 1 its easyer to pull using the new break in cilinder 2 i wouldn't run it without a filter anyway.. the bad running is surly because its out of balance...

Tks


ReMan - 21/4/07 at 11:17 PM

quote:
Originally posted by chris mason
why not just fit the airbox as it should be? cheaper than a sausage filter and probably gives you more power than one too!!

Chris

Fairly sure you need a bonnet with a bulge to do this.
IIRC thats why I have one.. as I wanted to fit th 'blade box

[Edited on 21/4/07 by ReMan]


mad-butcher - 22/4/07 at 07:42 AM

Isn't the bulge available as a seperate item or wasn't it modeled off kia sedona
Tony


RazMan - 22/4/07 at 08:22 AM

Just a thought - did it shatter due to a stone hitting it?


Peteff - 22/4/07 at 09:13 AM

Fireblade airboxes fit either way up don't they? You shouldn't need too much of a bulge with it straight on the carbs. You could cut the bonnet and just have a bit of the box showing through if you're already on the road.


ChrisGamlin - 22/4/07 at 01:43 PM

Yep, as long as the airbox doesn't foul the engine cradle etc, it can be mounted in reverse orientation to where it is on the bike, ie the same way as it is now in the pic above, so the main body points down towards the gearbox.


Jubal - 22/4/07 at 02:51 PM

Thanks for the pointers all. I'll try with the original airbox before going further. Raining all day here today and a list of trackday pennance chores have hampered any testing.


jack trolley - 22/4/07 at 03:23 PM

Are those pipes plumbing bends?
If so, plumbing waste pipe has a Max. Temp. of 50-60C.
Under bonnet temps. can often reach that range.
Also petrol vapours may be corroding the bends.


Jubal - 22/4/07 at 04:49 PM

quote:
Originally posted by jack trolley
Are those pipes plumbing bends?
If so, plumbing waste pipe has a Max. Temp. of 50-60C.
Under bonnet temps. can often reach that range.
Also petrol vapours may be corroding the bends.


Hehe. They've lasted over two years! Nice locost way to avoid cutting the bonnet by the guy who built it.

I've just binned them and quickly refitted the airbox. I now need a dry day to test. Here's hoping.


ReMan - 22/4/07 at 06:39 PM

quote:
Originally posted by Jubal
quote:
Originally posted by jack trolley
Are those pipes plumbing bends?
If so, plumbing waste pipe has a Max. Temp. of 50-60C.
Under bonnet temps. can often reach that range.
Also petrol vapours may be corroding the bends.


Hehe. They've lasted over two years! Nice locost way to avoid cutting the bonnet by the guy who built it.

I've just binned them and quickly refitted the airbox. I now need a dry day to test. Here's hoping.

So did the bonnet fit?


Jubal - 22/4/07 at 07:15 PM

quote:
Originally posted by ReMan
quote:
So did the bonnet fit?


No way! It needs a dirty great big hole making in it It's gonna look hideous but holes are cheap to make!


Jubal - 24/4/07 at 06:43 PM

The car works just fine with the airbox back directly on the carbs. Revs hard throughout the range. No apparent ill effects.

What I've discovered is that the engine will not rev out without static air at the carbs. A big thanks to everyone, especially those who u2u'd with advice and offers of help etc.

It's bl**dy ugly with a hole in the bonnet mind! Anyone have some edge trim knocking around? Or a bulge?