How to replace Air Filter?

[will108]

Hi Guys,

I have a gilera 50cc DNA working fine.
I have bought a K&N style filter, put in on and now the bike bogs at anything over half revs. (its ok on little power)

I have tried turning the fuel/air screw on the carb but no joy, so I have put the old original air filter on and everything is back to normal.

Any suggestions please?

Thanks.
Will.

[.....]

The K&N will be letting more air though so you'll also need to adjust the fuelling by altering the jets in your carb to compensate.

[Kickstart]

[Nope.]

Right, when you fit an open air filter to a two stoke you are changing the fuel/air mixture AND reducing back pressure, this means that you will effectively be running with too much air and not enough fuel as well as reducing compression. This really isn't good for the engine and drastically reduces performance. If you want to run with an open air filter you will have to upjet 10-12% if not more. This will drastically increase your fuel consumption. However, there is absolutely no point to you running an open filter. The open filters are designed for those with Big bore (>70cc) kits, larger carbs, sports exhausts and just generally tuned up engines. Basically, you've just wasted money on decreasing performance. You will probably find that even if you do upjet you will have lost a fair bit of performance.

Bung the air filter on the Variator air ducting. They look reasonable there and it wont affect performance.

This will explain the science of an airbox in better terms then I can here:

https://www.scootershack.co.uk/airboxguide.html


So, in summary, ditch the open air filter and stick with your stock airbox. Job done.
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Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400

[heehaw]

Did you oil the k&n filter?
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Its important, otherwise it wouldn't be there.

Retro Rider Bicycles: CB125TDC, CBR400RR, BSA Bantam.

[will108]

Boll***s.

Thanks guys.
I should have checked before I bought it.
£12 on eBay.

Not too bad, could have been worse.
I will stick to the origional one.

Will.

[Teflon-Mike]

[InspectaBike]

[Kickstart]

Hi

Don't agree I am afraid. You certainly don't have to change the exhaust to suit the filter to avoid losing power. But the gains from a change in filter will be tiny and the possible losses from getting the jetting wrong can easily be greater.

The exhaust doesn't care about the air filter, and it works from pressure waves dependent on rpm rather than any specific level of pressure.

All the best

Keith
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