Air filters

Dr Nick · World Chat Champion Joined: 20 Jun 2003 Karma :

Having my Major service next week and was thinking about putting a k&n filter or gibson filter on instead of the standard honda air filter as i apparently need a new air filter at 16k mile service, i asked the mechanic if it need rejetting and he said not really, i already have a Leovince end can on at the moment, and thought it would need a dynojet kit with both air filter and end can?, as it would run lean? attached is a scan of my dynochart which has fuel to air ratio on it if anyone could tell me if its running rich of lean at the moment? thought it would help

Thanks
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is that it

AcIdBuRnZ · World Chat Champion Joined: 28 Jul 2003 Karma :

I'd say that is a very nice power curve you got there Thumbs Up

No dips or flat spots - any idea what it was like before you fitted the can?

As far as dyno jetting, maybe you should fit the air filter and see how it runs first? Will it cost a lot to get it (dyno jetting) done?

I know K&N sell jetting kits designed to match their air filters. Wouldn't do any harm I suppose - think they go for around £30-£50.

Been thinking about this myself too, let us know if you do it Thumbs Up

Mark
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instigator · Super Spammer Joined: 19 Oct 2004 Karma :

I got a k&n filter in my er5 mark. Thumbs Up

Haven't realy noticed the difference really. First gear feels as if its more useful and my mpg has gone up (ABOUT BLOODY TIME)

I automatically assumed that when you got an end can and k&n filter, dynojetting came after that. I don't suppose its vital on every bike, but I suggest you run the bike and see how it feels, and if it wallows in power where you think it shouldn't, then you probably should have it done

Gracie Jones · Trackday Trickster Joined: 31 Aug 2004 Karma :

Can somebody explain what re-jetting is? Do they adjust the size of the jets in the carbs or what?

cc123 · Geez a joab? Joined: 17 Jan 2005 Karma :

Thats my next step. I wouldn't put a K&N on unless I had the DynoJet kit to match....

I don't think it will instantly make a huge difference but might start knocking the air/fuel mixture out after time.

Nick, how much did it cost you for your Dyno run? What was all included, just a run or some setting up?
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instigator · Super Spammer Joined: 19 Oct 2004 Karma :

If its just a run(usualy 2 or 3 minimum) and a print out of the power output, it would set you back anywhere between £30 to £60.

Mine cost £45 in stirling and that was with 3 runs.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

To be honest I am very doubtful of any claims for much extra peformance from a K&N. It still has much the same surface area and still retains the standard airbox. Difference in power (and fueling requirements) is probably about the same as the effects of the weather on 2 different days. Most people who will have fitted one will have replaced and old and dirty as hell filter with a new K&N, and noticed the gain more from that.

A can is more likely to need jetting changes while a full system designed for more power is very likely to need them (and that is where the main gain are to be had, rather than just bunging on a cheap can).

Rejetting involves changing various jets in the carb to change the fueling at different revs. Mainly (with a CV carb) the main jet size, needle jet shape, needle jet position and changing the hole in the slide transferring pressure above the slide to affect the speed it opens.

All the best

Keith
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