749 Homemade Carbon Airbox

I'm currently making a carbon airbox. Took a mould of the original and adapted it slightly. At present it should weigh in at under 800g. I used reinforcement carbon, unidirectional which is much stronger than a weave lay up. Of course it will have a final weave as in plain or twill and has Kevlar mounting points.

Now in the process of sanding, as can be seen in the last picture. I believe EVR are approx 1.2kg so will be well under and stronger. Then repeat it all again for the bottom section.

 

Its made strong enough as not to warp (from heat) or/flex under different pressures in anyway, not even 0.5mm as this would have massive effects on the bike. Although not directly connected to the frame, there was an article years ago, circa 2003-2004??? about running 749 999 airbox with less stiffness/strength to weight and how it has a huge effect on the bikes handling even though its not as critical to the chassis stiffness of, say, a 916 style airbox. It may have even been from EVR, but cant remember where, but I wish I could.

I used U/D tape as it has better mechanical performance than crimped (woven) reinforcement because as under tension, (or any load, such as air pressure) the straight fibres are not prone to 'straightening out' in the way that woven fibres do.

The cloth is held together by a very lightweight stitching which, unlike a 'woven' unidirectional tape, keeps the carbon fibres perfectly flat without the 'crimp' of passing over and under horizontal weft fibres. Still tricky though in the mould to work with, but OK in the end.

I used Kevlar at the mounting points, but only in the middle of the carbon layers as although carbon is much stronger/stiffer its weakness for me, in mounting points, is its too stiff. The amount of times I see hair line splits/cracking on mounting points in carbon. Its still one layer of carbon, two Kevlar and a final carbon layer. I just want the tiniest bit of flex in that area alone...Should be OK.

I kept the volume as standard as larger volumes require some dyno development work as it will change the amount of air going into the engine at every rpm, so the fuel map would have to be altered and really can't be bothered with that as its a street bike.

The 749 999 airbox volume minimizes mid range rpm dips when it comes to the torque curve, race bikes use a larger airbox to gain red-line power....like the EVR one is designed for.

So, to put a larger airbox on a stock bike which is used on the road, will degrade power in the frequently-used rpm range just to get a higher maximum power...and thats only if you do the dyno or develpment work.

So a larger airbox for me is good for a race bike that lives at high rpm, but not for a street bike where you are not hitting that massive power range.

Anyway, thats all my thinking behind it! I made one for my old TL1000R, although 749 is a little bit more intricate.

 

Got the lip on by placing it on a flat board and putting the carbon on from the side and down to the board. Came out very well, I anticipated some sanding but was spot on. So now it's a case of sanding everything smooth. The volume of the top compared to stock is within 10ml. I measured by plugging all holes on each and then pouring into a container and weighing on digital scales.

 

Thanks, it will be a while before its finished as I spend an hour here and hour there...Due to family and work commitments. I did make my own single headlight conversion and various other lightweight items.

 

Will upload in a few days time for you

 

I have big feet!...Nah I bought them from avanti race and didn't realise they had the wingspan of the A380, but yes I will change them out, not too clever when filtering through traffic!

 

Here is the breather, I used the original plug and drilled through to insert the tube. I could not find the proper breather adapter anywhere to buy. Luckily I have a spare plug for the tank. It runs through two ball valve, think it was Hi-Flo who makes these and then runs into a conical in the nose unit which I have taken off at the mo as I am re-crimping a few electrics.

As you can see, I have a SES aluminium clock brace and projector light so there is a huge void where the headlight unit used to sit. So plenty of space to house the conical. I just used a couple of tiny ty-wraps to keep the line in place and that's pretty much it.

 

Bj

Ah I see! It is not on my bike at the mo as it is an ongoing project, it's at my work. All I'm doing is carbon the outside of the original, then will cut exactly in half. Remove the original and coat the inside of the carbon in a chemical resistant coat and put the two halfs together and then a final layer of carbon to hide the joins. Won't change anything performance wise but just hate the black plastic.

 

To be honest, it should not be too complexed for a company to make...but as you say they would charge £££. I was thinking that the breather could be more of a box shape as its only the side that sits next to the frame which is a little complexed, I reckon it could be simplified as long as the volume of the box is near enough. Suprised no-one has ever produced one. I'm bored of all the usual carbon like tank protectors, clutch covers, etc...I would like to see the more unobvious items manufactured!

 

That looks very tasty!