Running without an air filter for short periods of time?

[CorriganJ]

I have a Hyosung GT125 and I want it a little bit faster. Just a little. I've heard that de-snorkelling these is a valid performance upgrade, but before I take a hacksaw to the air box, I wanted to test and see what increased airflow actually does, and if it helps. If I remove the air filter for say, a 30 minute ride up the highway and back to see what top speed does, will I kill the engine? Thanks

EDIT: would removing the air box entirely de-snorkel it too much and give too much air causing it to run lean and have lower performance?

As I understand it, the air box is snorkeled to limit air intake to bring the engine down to under 15bhp to meet EU regs for bike categories? More air = more power, but, does too much air equally cause it to loose power again?

P.S. I know the response I am going to get is "don't bother upgrading it, its a 125, it is what it is, get a bigger bike". Totally valid, I wish I could do my big bike test, I'm looking into ways to do it abroad but its more complicated not being in the UK. In the meantime, I'm on the highway getting overtaken by lorries, and I want to find another 5mph or so if I can to avoid being squished (here you can ride a 125 on the motorway without a full license and I have to sometimes. But its scary).

[Nobby the Bastard]

If you remove the air filter the mixture will be far too lean. Whether the efi can cope is a matter of conjecture. I cant see it gaining g any power and its more likely to cause it to jump into limp home or melt the piston.

Snorkels are used under water. Are there really deep puddles.where you live?


Disclaimer: bike manufacturers spend millions developing the intake of bikes. Do you really think that fucking about by removing the air filter is going to get you more power?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[xX-Alex-Xx]

If you want to go faster, you need a bigger bike. Even a 10% gain is netting you just over a pony (And you won’t get that with dicking around with the intake). You won’t notice any gains even if you find some.
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DILLIGAF

[Hong Kong Phooey]

It's not the air filter or induction system that's restricting you to 15bhp
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[P.]

Is this the one in Spain.

My old 2008 one had an SV650 K&N in there with the airbox desnorkled. It was upjetted. There were different jets front and rear, so make sure you don't just fuck it.

But, they aren't fast, see the size and weight...

[Riejufixing]

[Nobby the Bastard]

Actually damp conditions are more.likely to clog up an air filter.

I used to have to pull the k&n off my dt if it started raining just to get the bastard started. Giannellli of road only pipe....
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Riejufixing]

[Nobby the Bastard]

[Riejufixing]

[CorriganJ]

Thanks chaps - probably going to leave it as it is then. There are "performance" air filters on the market that let in more air (60mm intake hole instead of 40mm) for not a lot, so might give one a try. On the other hand I've been spending money hand over fist on gear so might try not spending anything for a while.

[Kickstart]

If you are really unlucky, without an air filter 1 stone could wreck your engine. More likely grit will increase wear.

As to the snorkel , a well designed one should increase flow through a hole. Just removing the snorkel and leaving a hole of about the same size would probably flow quite a bit worse, but be noisier.

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[xX-Alex-Xx]

[1198]

I tried running with a drilled air box lid. The bike sounded great but was gutless, wouldn't pull over about 2,500 rpm and felt horrible. It was a carb bike but the logic is the same I believe, the fuelling was screwed up massively!

[A100man]

[Easy-X]

More air in, okay... but how's the exhaust? Best think of it as one long pipe or chain:

Snorkel [in your case] > air box > filter > carb/throttlebody > cylinder > exhaust manifold > cat [on newer bikes] > silencer

So you piss about with the first but what about the rest?! And even then, you'd have to shove more fuel in to compensate! EFI? What should be happening is the ECU sees a lean condition from the O₂ and throw in more fuel. In practice it'd need to be tuned to adjust the base map.

Setting aside forced induction for the moment there's only so much you can get out of the central restriction: 125cc.

Most 125s are built to ~10kW so the best you can manage is to squeeze a touch more out to reach the legal limit. Even if you ignore the legalities the best you could probably expect is maybe 13kW? As it is the specs on the GT125 say it does 11kW - it's at the limit and really has little scope to practically go much further.

Let's be really, really generous and say you squeeze 10% more out of the engine by optimising everything you can. Great, but that doesn't translate to 10% more speed!

tl;dr 10% of fuck all is pretty much still fuck all
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[CorriganJ]

[CorriganJ]

[ThunderGuts]

[Riejufixing]

[CorriganJ]

[WD Forte]

I saw this link when googling to see wtf a HyosungGT125 was

it might offer some insight.. it might not

https://hyoriders.club/forums/topic/tutorial-hyosung-gv-gt-125-250-how-to-swap-carburetor-main-jets/
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bikers smell of wee

[steve the grease]

I knew a girl once who had a Triumph 500 which developed a curious misfire , it was after she had bought a tasselled leather jacket. The tassels were getting sucked into the carb. Whats an air filter?
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All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of.....

[spottedtango]

This is classic 125 frustration. We’ve all been there. I wouldn’t run the bike without an air filter.

You’re better losing weight from the bike than dicking about with it in that way assuming you want to be able to sell the bike on eventually.

[Easy-X]

125? Need moar powa? 3 choices:

Nitro

Turbo

Rebarrel
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter