A question about the intake system [Archive] - ApriliaForum sponsored by AF1 Racing, inc.

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GV2NIX

10-18-2005, 09:42 PM

I read this thread (http://www.apriliaforum.com/forums/showthread.php?t=65665). Very informative! Thanks to all who contributed to that one.

I have a question regarding the other end of the system. I know it was mentioned in another thread that a pod filter makes things smoother, but what does it really do, and how is it different from the normal air filter? I'm guessing that any performance air filter, on top of catching particles, should be designed to create the least flow resistance and a stream of air with low turbulance right? Does this go for both the normal air filter and the pod filter? Thanks in advance! :)

Edit: I just realized that a pod air filter is probably the normal air filter right? Am I a dumbass? Haha!

RS50 Owner

10-19-2005, 02:33 AM

A performance airfilter is designed and supposed to let more air in to the engine. But some people see this mod pointless because it can turn out to be more trouble than its worth, Because they've been known to let shit through and in to the engine...

Most people just drilled holes in to there filter instead,...

williamr

10-19-2005, 02:55 AM

We've talked on another thread somewhere about 2-strokes being a resonant system, from intake through to exhaust.

While an after market filter may flow more air in static tests, a good airbox will pulse the intake air and actually get more into the cylinder, as long as the filter isn't too restrictive.

It would be interesting to dyno test aftermarket filters against the original with different pipes and levels of port work.

Don't forget to check your jetting if you make any changes.

Rob

GV2NIX

10-19-2005, 07:19 AM

Moorie

10-19-2005, 07:31 AM

** just to clarify **

u dont drill the actual filter..

You drill the box above the filter!!

GV2NIX

10-19-2005, 08:02 AM

I didn't know there was an air box, I thought the filter was just sitting there fully exposed...?

Davido

10-19-2005, 09:17 AM

The case is not counted as the air filter. The bit that's underneath when you unscrew it is the actual air filter. As Moorie said, that's what you drill.

If you wanna have a look, unscrew the bolt at the front of your tank and lift it up. Make sure you don't pull out the fuel line though, like me. :)

GV2NIX

10-19-2005, 09:34 AM

Any drawbacks to drilling the air box? Why don't manufacturers make intakes larger to begin with? I suppose smaller intakes would save fuel huh?

ExtremeAcres

10-19-2005, 10:21 AM

I believe that the airbox is so sealed up , for wet weather riding.....It only has that one intake hole.....and it is hidden and protected very well..... For most of us who hate the rain and choose not to ride in it.... Drilling the airbox, above the filter, might be of a little benefit......
But if you were to get caught in the rain( anyone who rides everyday to work or school or such)... The worst would be getting caught in that Huge mist when following a car or truck in heavy traffic, while running WFO.... this Could take in much too much moisture and run it through the engine, and while the engine may keep running (but wont run as perfect) You would be washing all the Crank bearings and rod bearings and everything that is in the lower end and top end of the engine...With WATER.... This will put Excessive wear on parts and shorten the life of the motor dramatically....
Just my opinion as to why the airbox is the way it is... :blah:

GV2NIX

10-19-2005, 10:23 AM

Makes perfect sense to me, thanks! :)

D148L0

10-19-2005, 10:35 AM

Any drawbacks to drilling the air box? Why don't manufacturers make intakes larger to begin with? I suppose smaller intakes would save fuel huh? And it reduces intake noise. The stock RS50 is very quiet compared to a modded one.
As williamr said, the airbox contributes actively to the air inflow. Do a search for "holes in air box" or similar topics in this section, there is one post made by the AF1 guys where there is a picture of where to do the hole/holes (they recommend a total of 2" drilled) and the explanation of pros and cons of drilled box vs pod filters vs stock box, etc.

I cannot stress enough the use of the search function and to see who makes the post. While most guys around here mean well, a lot of times the advice provided is just... not accurate.

GV2NIX

10-19-2005, 12:23 PM

Been reading up and it seems the stock oil pump can handle a 21mm carb, but what about a 24mm carb? Heard that it's not safe to run the oil pump and I should go premix? Is this true?

SpikeR

10-19-2005, 12:52 PM

when i put a 25mm on i went pre-mix. much safer imo.

GV2NIX

10-19-2005, 01:07 PM

If I went with a 80cc bb kit, do you think I would need a carb bigger than 21mm?

fast_tzr

10-19-2005, 01:37 PM

nah, im gonna get an 80 with a 21mm, though I am considering a 24mm, not sure if a 24 would be worth it though, and i'd be running oil injection so if itsa gonna bust that up....

GV2NIX

10-19-2005, 01:42 PM

Hmm, I see. Why don't you think a 24mm would be worth it?

fast_tzr

10-19-2005, 02:28 PM

well for a start it worsens the fuel consumpstion, and also i was reading some thing about some people that had a 21 on their bike, then switched to a 24 to see how much of a difference it would make, and their lap times only increased by like 0.2 of a second or something.

GV2NIX

10-19-2005, 02:30 PM

Oh ok, I see. I guess it would only make a difference if you went nuts with a 28mm, got rid of the oil pump, and had a super high flow exhaust purely for racing, haha!

I'm glad a 21mm can feed an 80cc big bore because I don't want to mix!

fast_tzr

10-19-2005, 02:39 PM

lol yeah me neither!

SpikeR

10-19-2005, 03:54 PM

21 wont give very good performance on an 80cc kit, a dellorto 28mm would do the job nicely. i ran one on a 71.8cc MK SP kit and it worked a treat, fuel consumption was still okayish. i got around 50 miles to the gallon atleast.
spike

GV2NIX

10-19-2005, 04:25 PM

I guess if you really want max performance, you have to go with premixed fuel huh? =T

fast_tzr

10-20-2005, 10:37 AM