Cheap Airbox Mod

[Blakes7]

I'll try to keep this short and sweet (that's what she said!).

If you have a UK/ Euro spec CB500 (any variant), the velocity stacks (tubes inside the airbox) have an inbuilt restriction, as an easy way to ensure A2 licence compliance.

Go to Partzilla.com and order;

17251-MGZ-A00 FUNNEL, L. AIR (Honda) $7.57

17252-MGZ-A00 FUNNEL, R. AIR (Honda) $7.57

It's another $15 for delivery and takes about 10 days. 

Whilst I was in there, I binned the snorkle and opened up the air filter cover, so that the air can get through.  Keep enough of the cover that it can seal against the foam part of the air filter.

You can either trim back the air filter plate (as I did), or go to racingairfilters.eu and buy a foam filter which already has the plate opened up.

Change the velocity stacks over and put it all back together.

On the road, it has a slightly stronger midrange, revs out easier and has a nice intake growl.  Bum dyno only, as we're cheapskates, so no lovely before and after figures- sorry :( Son's bike has a Scorpion silencer, so it's all nice and throaty :)

So, there we have it.  Wait until the air filter needs changing (or valves need doing), order up the bits a few weeks before and say hello to easy power.

Your bike will of course, no longer be A2 legal.  But... since you would have to open the airbox AND know what to look for, let's face it, you're never going to get caught by Larry Law.

BTW, whilst I was servicing the bike, I noticed there wasn't any vacuum take off point, to sync the throttle bodies. WTF!!!

If you need any advice, or whatever, just let me know.  Also, please let me know how you get on.  Regards, Nick.

[Rexelstar]

Great research and info!

Thanks.

 

[slowrider]

Interesting.   

How does this affect MPG?

[Blakes7]

Originally Posted by slowrider

Interesting.   

How does this affect MPG?

Too soon to tell.  It's only been a few days.  I'll get back to you in a few weeks.  Nipper does a long commute and knows exactly how it costs, so it should be possible to give you an accurate answer.

On a side note, I took it out for a longer ride this evening and I can confirm that it rides much better.

[Jaws]

Originally Posted by Rexelstar

Great research and info!

Thanks.

 

As a matter of interest, whats to stop you simply cutting the restriction plate out ?

[Blakes7]

It's possible John.  It's what I would have done, had the OEM option not existed.  It would be quite fiddly to do a neat job though.  Not worth the hassle for £25.  It's not just like tapping a washer out of our 125s  exhaust

Check out the photo that looks like a smiley face; you'd have to cut out the sides without cutting through the 'main tube'.  If you want the FOC option though, you could do that.

What brings you into CB500x world John?  Blackbird too fast for you ol' timer 

[Blakes7]

BTW folks, I forgot to mention in the original post, I also blanked off the PAIR valve with a 12mm blanking plug at the airbox end and with a bolt and jubilee clip at the hose end.

No idea if this made any difference- it did on my old VFR.

[Jaws]

Originally Posted by Blakes7

BTW folks, I forgot to mention in the original post, I also blanked off the PAIR valve with a 12mm blanking plug at the airbox end and with a bolt and jubilee clip at the hose end.

No idea if this made any difference- it did on my old VFR.

Are the new ones completely open ? I.e no restrictions at all ?
If so then I can see a job in my future.. could even stick it in the lathe to ensure a neat job 

[Blakes7]

Originally Posted by Jaws

Are the new ones completely open ? I.e no restrictions at all ?
If so then I can see a job in my future.. could even stick it in the lathe to ensure a neat job 

It wasn't a newer one, it's an American part, which is different to the one we get in the UK.  It's a different part number, for a different market.  Not sure a slightly curved rubber tube is the most lathe friendly medium.  A nice shiny aluminium one could work though...

From what I can see of these forums, other than the Rally Raid stuff, CB owners don't really seem to have embraced the farkling lifestyle.

[Blakes7]

Actually, on second thoughts, there might be a (limited) market served by selling the US stacks, a blank plug, modified cover (Probably milling a big circle in the middle will do the job) and the aftermarket filter- all as a kit.

Wish there was something like this on GSs ...