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Discussion Starter #1
Hi Everyone,

Just researching some information on my bike (1999 GSXR600) and come across a post off some other site saying:

"One mod that is quite good is pull the crankcase breather hose off the back of the airbox and stick a mini K&N filter in it. Tie it to frame with the pipe as vertical as possible. Block hole in airbox with silicon. This stops all that warm crappy air goin into it! good for 1.5-2bhp on a normal day! Only downside is sometimes at lights you might wiff the oilly smell a bit but never too much really. "

I guess what i want to know if its true and if theres any detrimental effects from doing this? I like the idea of keeping the warm/hot air out of the airbox....but am wondering if its going to make the bike bog down in certain rev ranges or any other crazy stuff (loss of power etc)
?

What do ppl think? Please don't flame me if this has been asked before -- i did a search and couldn't find anything on it.

Cheers,
Rob
 

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Can't think of anything. Should allow the bike to run slightly cooler = more power. Not very environmentally friendly.
 

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Discussion Starter #3
I must admit I didn't think about the environmental aspects..I might try an experiment to see if its worth it, but i'll consider a way to let the crank case breath into a carbon filter or something so i'm environmentally friendly. (I do respect mother nature)

Thanks for your reply

Rob
 

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Please bear with me here as i am not a bike tech but an auto tech so i am going to generalize a bit, but same rules should apply. when you open throttle you are creating a vacuum effect in your airbox (although i dont know to exactly what degree) that in turn is is also then pulling vacuum from your crankcase. So by disconnecting that you now have to count solely on your engine preassure to vent it on its own (again albeit a nominal amount). The effect of changing that is going to be nominal at best and should not cause you any trouble. Now on the flip side of that with the airbox location on a hot engine, and the small amount of hot air that you would be pulling from the crankcase, would probably be so small i would highly doubt you could feel any differance, let alone probably see any differance even on a dyno or at the gas pump. Again i could be wrong here as i am not a bike tech, but i know as far as cars most people do it to clean up an engine bay from all the emmissions clutter not because of any realy hp or fuel gains. Hope this can help you though.
 

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I actually produce and sell kits that take advantage of the performance gains to be had by doing this very thing. My versions are alot cleaner, however, than just sticking a K&N filter on. Unfortunately, I don't have any versions available for SRADs yet, but should in the next month or so.

Regadless... here's a link to some good info I've posted up on the subject:

Crankcase Ventilation FAQ

TK, there are actually noticeable gains to be realized, especially if your bike is running loose rings. And I'll tell you one thing... most every SRAD I've seen has loose rings!


Seriously though - the advantages aren't limited to mild HP increases. Clean valves, reduced carbon deposits in the combustions chamber, blah, blah, blah - all add up to increased longevity and increased performance over the life of the engine.

And as far as vacuum goes, for one, that's vacuum that could be better used sucking fresh air & fuel into the engine. Also, the vacuum's never constant... in fact, at small throttle openings at higher bike speeds, air's being pushed into the crankcase, causing positive pressure conditions
 

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Biggest advantage that I can think of is one less vacuum hose to have to hook back up

I have done a similar mod on a car that I had because the intake tube that I put on did not have a hook up for the breather. I put a filter element on it where it comes off of the motor to prevent oil from venting directly into the air. Worked well (of course no power gains to speak of, but I did not expect any), and no oily mess. I would say go for it! Will keep your air filter a lot cleaner too!
 

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I wasn't correcting you bro... you have valid points. I've just spent an inordinate amount of time researching this subject, for obvious reasons


I hope to have some good solid data posted sometime in the very near future, comparing performance increases and pressure conditions between bike's running with, and without, the breather routed into the airbox, in as controlled an environment as possible. I'm also planning on making direct comparisons between bike's running a breather outlet into the atmosphere, versus using the PAIR valve (PAIR mod). But I'm holding off posting my preliminary results (which have all supported my assertions) until I collect statistically meaningful data from a number of motorcycles. Unfortunately, without a wind tunnel, it's hard to quantify the effects of RAM Air/Airbox pressurization at speed. I'm pretty much just going on theory there.

Know anyone with a wind tunnel?
 

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Discussion Starter #9
Thanks for the replies. Good to hear both arguments. LeanAngle:thanks for the info (read your FAQ's), nice work. Your kits look pretty slick (compared to just chucking a filter on the end of the crankcase ventilation hose).

I'm in Australia, and only now the weather has cooled, i've been riding in weather up to 43 degree celcius (and in traffic) so i'm going to experiment. I was a bit skeptical until I heard a few other opinions who had more of an idea than me.

Thanks again, I appreciate everyones feedback.


Rob
 
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