A buddy of mine P/U a KN air filter Crusher slipons and Vance & Hines fuel pack my question is How do u modify a stock air cleanerso the bike breaths better he wants to drill out the backing plate has anyone done this before...

 

Since he's committed to using a Fuelpak, he'd better stick with parts they have key-codes for or he'll be SOL getting a "good" tune. If they have one for "modified stock airbox" then you'd better find out from them just exactly how to modify it. But I'll bet they don't, so he'd best not do it.

 

Is the K&N for a stock air filter assembly? If yes, then it qualifies as a high flowing air filter for the Fuelpak. He can always drill holes in the "football" so the element can breath better. The Fuelpak is designed for all free flowing air filters. I slightly modified my Arlen Ness Stage 2 by making a cover from a Harley derby cover so I have a completely exposed filter element. The Fuelpak will be fine as long as he chooses a map for his bike and exhaust. If he does not see what he has from the V&H site, then he can contact them for a recommendation. The Fuelpak is an excellent choice for anyone who just wants to add slip-ons and an air cleaner since it is easier to use and cheaper than its competition regardless of the what others say.

 

Whatever. Easy to use is in the eye of the user. Most folks think Microsoft Windows is easiest to use but whenever I have to sit in front of a computer running that crap I feel like I've got handcuffs on with a very short chain between them. It's way too difficult to do any useful things without almost entirely transforming it into a Unix clone of some sort.

A replacement filter element in the stock airbox does not qualify as a high-flowing intake. The design of the airbox itself is the limiting factor. The effect of the filter element inside is almost negligible unless it's very dirty. Different flow dynamics at various impulse frequencies is what needs to get tuned to. One high-flow airbox design can be quite different in that respect from another. Making additional holes in the stock airbox will open up a whole can of worms that can be properly dealt with only when using a fuel management system which can be fine-tuned to the specific conditions. If there is not a map already developed, or if V&H aren't willing to do so, for specific components, then using one that's "close" will only net you "maybe almost good" results.

I don't like the Fuelpak. I don't like the business model. It's like Microsoft. "You don't need to know how what does what, just use it the way we tell you to. You'd likely mess things up if we told you how to do this stuff on your own." If a person is not the tinkering kind and they want to only use parts which match the parts the V&H engineers have chosen to tune with, then it can be a viable option. It's not the cheapest, it's not the most capable, and it's certainly not the easiest to use. It ain't bad so long as all the criteria are met. For many purposes, for another $20 or so, the PC-III will flat out leave the FP in the dust in all three of the cost, performance, and ease categories. But they're both piggyback units, with the common downsides of that option as a whole.

This particular question, about opening up the stock airbox, squarely flies in the face of the Fuelpak. Either use a different tuner or purchase a prescribed airbox assembly to use with the FP. Life's too short...

 

The KN is for a stock air cleaner ..I think maybe he should buy the full kit seeing that no one here has done one yet I will keep u guys updated....

PS I personaley have used Fuel Packs in the past w/ no problems but I now use a SERT.

 

Okay, I'll jumped in here thinking I've read everyone's feedback and offer my 02 cents. First let me ask this question: Why drill the holes in the air box? Will the holes serve as multiple opening for the extra air to pass through? If so, then what I have done, (I am a tinkering type of guy) is what you are looking to adopt. I hope I can paint a good picture as I describe the result from my madness.

take your stock airfilter. now imagine the eliment that is bonded to the two sheet metal and replace that with a K&N filter and bond it the same manner as the stock filter and able to use your original "football" cover. But the only difference is the K&N filter is an inch or so thicker than the stock filter. Hence it will push the footblall cover away from the plastic half mounted on the intake. If you have been around in the V-8 world one of the trick us old guys use to do was turn the airfilter cover upside down so the entire perimeter of the aricleaner is open. Well picture that result except it's vertically.

I hope these photo take.

 

with this set up the only thing I can think of that would offer better air flow is a larger dia throttle body. Maybe I am wrong but this set uses a K&N filter with the stock structure as the main base and using original parts.

 

Drill out the backing plate? Might as well poke holes in the air filter. The non-stock K&N air filter is wider, has a K&N backer plate and kit fits under the stock cover, but the Air Filter area is hugely increased and air flow is increased. Fuel Moto sells them.

 

The K&N stock-replacement filter element may be able to flow more than the stock element can, but that's not the limiting factor here. The limiting factor is the design of the airbox. The only effect the K&N will have in the stock airbox is that which a really, really clean filter would provide.

I would not modify the airbox without being able to tune the EFI to particularly match the end results. Yeah, I know, I've turned the air filter cover over on my '70s cars, too. But these ain't them.

 

Guys thanks for the feed back believe it or not he got this idea from some guy who works at a harley dealer parts dept..I am also a tinkering type of guy but after and long conversation w/ him he has decide to go w/ a S/E High flow air cleaner and KN filter...Thanks for all the imput