NU50 Custom QUIET Airbox

Just finished fabbing up my Urban Express Super high flow and super quiet airbox rig. Cuts noise level tremendously.

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Re: NU50 Custom QUIET Airbox

There's other stuff on your bike that's far more interesting than your airbox...

Please feel free to talk a bit about you setup!

Re: NU50 Custom QUIET Airbox

That looks cool! would you mind PMing me with parts/instructions? i'd love to make one for my magnum.. i'm getting tinnitus!

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I'm glad I looked at this.

Pretty cool set-up; at some point you should spill the beans on the rest of it (I know what it is, just want some details and results).

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I have tried to get into detail about the nitrous setupbefore but wayne or ryan usually jump in and say how it doesn't work. the truth is its works flawlessly and have been running it for years, the bike will run over 60 mph from a dead stop in the the 1/8 mile in 10 seconds. top speed so far is 72mph gps in about 1/2 to 3/4 mile. the bike has a malossi liquid cooled kit which is unbelievable kit (the air cooled kits just got too hot too fast for reliable nitrous runs) electric water pump, never runs over 150 degrees, vm20, hobbit peoples pipe, 2 stage reeds, adjustable timing. top speed no bottle is right at 60mph, actually a real good cruiser now with this quiet air box setup. waiting on a progressive nitrous controller which I had on it but it was acting up and had to send it back to cold fusion, nitrous needs to be ramped up slowly or the bike want to flip backwards violently and breaks spokes all the time. my brother runs a different nitrous setup on his na50, with nx50 motor and a liquid cooled malossi belt drive water pump setup and speed around the board are similar to mine, he might be able to just squeak by me but but its close, his has a dry setup so he has to jet his dellorto red race 21 carb all the way to around a 120 when he uses the spray making it not as user friendly as just turning on the bottle and flipping a switch. the urban has electric fuel pump for the nitrous and both bikes have auxiliary 1 quart fuel tanks that run 110 octane for nitrous runs.

Re: NU50 Custom QUIET Airbox

So cool, thanks for sharing.

If you have links to some video I'd like to see.

Re: NU50 Custom QUIET Airbox

david! this is my swap I just finished!

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hell yeah. just wait till u run those 14inchers!

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Heres some pics of my brother derek's nitrous injected na50

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Re: NU50 Custom QUIET Airbox

Cox Brothers running the Express game!

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Have been since early 90's! Thousands of long hours tuning and many blown up engines testing to boot!

Re: NU50 Custom QUIET Airbox

So cool!

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Thanks for the info! I'm going to rig one of these up asap!

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That thing looks like the ones on a Caterpillar bulldozer or a Freightliner truck....

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lol..funny shit!

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This is amazing. Good work dude! Would love to see a video!Edited 1 time(s). Last edit at 03/19/15 08:04PM by jeremyfreeze19.

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yes officer, it's toootaly stock.

impressive, but will the u shaped tube work itself loose from the carb from repeated shock compression? the big cylinder is mounted to the frame right?

not very performance related, but did you mount the fender to the pipe? pics?

i like seeing na50 framed builds, but that shock weld looks kinda scary.

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You know I love me some air boxes.

The larger the box, the more flow.

It looks like an evaporative canister.

Sweet.

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I agree on the shock welds but it was done 3 yrs ago and hasn't failed, trust me at high speeds it enters my mind whether it will hold or not, so far so good though. david normally does the welding but he wasn't around when I did the shock mod so I grabbed the welder

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its a donaldson cyclonic air filtration setup of 99% of commercial mowers sold . this one was from a 36hp vangaurd big block 993cc engine. It has 2 filters inside which we could care less about but they absorb the sounds tremendously. Yes its mounted to the frame and the tube is so long it cant work loose. The ridiculously large size allows no restriction on airflow but lowers the sound level by 2 or 3 times what it was maybe more. At cruise speed around 50 mph it sounds like a stock urban! it did seem to lower the rpm range of the power band but not overall power. bike still hits hard and will run 60mph with no bottle. it is quiet. we have learned intakes make 3 times as much noise as a pip ever will! wish companies would sell aftermarket airboxes for kitted bikes.

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Even a short small airbox in the good kart style shape (rounded terminal end, with right angle air tube inlets on the side) makes a huge difference in noise with very little performance change.

I just can't stand the sound of a 24oko wide open no airbox.

So fucking loud!

One of these days I'll moped again. :)

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Derek ordered this for his na50

http://www.racingplanetusa.com/airbox-racing-kartbox-2850mm-p-2448-1.html?utm_source=google&utm_medium=google_merchant_us&utm_campaign=google_products_us&gclid=CML09ZCvt8QCFdgSvQodnAIAKQ#.VQxNBo7F-So

Hopefully it quiets his some, his is the loudest intake i have ever heard with the dellorto red race carb. You can here it all the way across town!

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I think Crazy Wayne and DPCRyan are on to something.

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Road Rash Dave /

Love the TriZ and the 200x i believe...had a tri z first year they came out..awsome machine

Back to the air cleaner..I knew what it was and would use one as i can get it for free

I work at a mower shop lol

its just to big for my tomos...

And i like Jbot hate carb noise

Awsome

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yep, 85 triz and 85 200x. the z is a beast but the x is much funner to ride overall..but hell, we love 2 strokes so we go with the z!

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I have a big update. I found on ebay a smaller donaldson unit to use for this airbox. Its 4 in shorter and a couple inches narrower. Donaldson # G042544 on ebay. $89.99 shipped and comes with everything including the canister, air filter, cover, and mounting bracket. The on i got has a straight 44mm house connection but they have one with a 90 degree for same price. I went to oreillys and bought a radiator hose that will work for $10. $100 invested total. This setup will go right onto a mikuni vm20 carb. I am pretty amped bout it cus the other one was so big. It will be a week or so before it comes in. i will post updated pics of the smaller unit when i get it mounted.

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200x is a joke, Ive ridden a 200x and loved it but then got a 350x... no pics :\

dang how'd i miss that... in the pictures...

Just picked up a pumper 250r ( 87 4wheel) so sick, keeps up alright with a 450 dirtbike but doesn't beat it for sure.

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200x is classic for what it is. we like it and that is all that matters.

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Where the hell did you guys come from?

This blows pretty much every noped build out of the water.

Seriously, SERIOUSLY impressed.

Also that radiator placement on the NA50 is perfect. Almost like it was meant to be.

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thanks homz, have had the na50 since 1991 and been messn with express's since, we don't put alot of the info about them on here do to nay sayrs but will private message alot if people need info, Davids nu50 had a peoples pipe but I (Derek) kept dusting him so he went back to the h95 and it is alot better, now he can run right beside me and his bike is much heavier

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