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mc21 hrc air box dimensions


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fenton
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mc21 hrc air box dimensions

Sun Dec 09, 2007 11:27 pm » Post: #1 » Download Post

can any one tell me the dimensions and angles for the mc21 hrc air box ? as i am looking to make one for myself over the winter
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j911brick

 
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Mon Dec 10, 2007 12:09 am » Post: #2 » Download Post

I have one, but I'm out of town right now. Its pretty much the same as the stock box, except without the lid or filter.
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Mon Dec 10, 2007 1:30 am » Post: #3 » Download Post

It's much bigger than the stock airbox.
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mick

 
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Mon Dec 10, 2007 9:33 am » Post: #4 » Download Post

Did anything come of the NSR-World HRC copy?
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StephenRC45
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Mon Dec 10, 2007 9:50 am » Post: #5 » Download Post

Theres one on the racer and I think Maxim had one as well so they are out there. I wouldn't mind a copy one or a ram air system now I think.
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fenton
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Mon Dec 10, 2007 11:13 am » Post: #6 » Download Post

if you get one Steve i can copy it for you mate what color gelcoat would you like
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Mon Dec 10, 2007 11:26 am » Post: #7 » Download Post

I have one of Andy's genuine ones on my bike right now. We did have a few but they seem to of got lost somehwere.
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fenton
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Mon Dec 10, 2007 11:29 am » Post: #8 » Download Post

just thinking roy mite have one on his racer ?
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Mon Dec 10, 2007 11:31 am » Post: #9 » Download Post

Roy might have, I can't remember.
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fontyyy

 
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Mon Dec 10, 2007 12:13 pm » Post: #10 » Download Post

Roy's got one.

Anyone dyno'd it back to back with a modded airbox?

I've run;
Open airbox, (i.e. no lid)
Modded lid (2*1.5" holes)
Open carbs.

Open carbs made 1-2 bhp more at peak but cost 3-4 bhp all the way up and past 10,000rpm.
Modded lid wasn't dyno'd but felt like it made even more mid than with an open airbox, wheather it cost even more at peak I don't know, it was a lot easier to get off the line to.

Whatever, modded lid would be my choice, I haven't got the skill, the practice time or the gearing options to setup on every track so finding myself way under 10,000 rpm with a 400 breathing down my neck is all to common an occurance.
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StephenRC45
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Mon Dec 10, 2007 12:45 pm » Post: #11 » Download Post

Ive got some back to back graphs on open carbs vs moded air box on a 300 but I dont think any on a 250.

Maybe we need your bike back down Fontyyy and try all 3, plus I've got the funky fly wheel we need to try for extra Bing!
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j911brick

 
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Mon Dec 10, 2007 2:16 pm » Post: #12 » Download Post

Have you tried just an open air box? I would think this that would be about the same as the HRC air box if not better. But something to consider: the dynamics of the air flow around the bike are going to make a big difference on any tests without an air box and you test test that on a dyno.
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StephenRC45
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Mon Dec 10, 2007 3:57 pm » Post: #13 » Download Post

I've done some runs with open stock air boxes (oe boxes) but even like that the peak power isnt as good as the HRC box, or lack of it. The HRC air box isnt really a box though is it, more a means to stop large bits of crud getting in carbs.

I tend too agree with Fontyyy, a stock air box with a couple of holes in it does feel the most responsive on the road. However a good set up with the HRC air box can feel almost as good in the middle with the extra zip at the top.

A good half way house is the pod filters.
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cgallant
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Mon Dec 10, 2007 5:10 pm » Post: #14 » Download Post

I was going to say my HRC "air box" I had on my MC28 wasn't really an air box but more a rock guard for open carbs. that and it helped keep fuel/oil blow back from getting all over everything (with exception of the underside of the tank).
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Andy
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Mon Dec 10, 2007 5:30 pm » Post: #15 » Download Post

mick wrote:
Did anything come of the NSR-World HRC copy?

Um, if I recall correctly, Roy has one, the racer has one, SteveC has one, Maxim has one, there's one in Belgium somewhere (can't remember who that was!) and the prototype is with the moulds, hidden away in a lockup somewhere until we can arrange somewhere suitable to restart manufacture.

I don't even have one for mine... good eh? Sad

I do have a ramair kit though! Very Happy
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