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TLS Airbox mod advantages ???

5K views 11 replies 8 participants last post by  smokinn85 
#1 ·
Hello.
I was just wondering what is the benefit of the airbox mod ? Is there evidence that it increases HP and where in the rev range ?:dowhat
I do not want to go throught the trouble of stuffing around with it and butchering the airbox for 1-2 hp gain at the top of the rev range and maybe lose HP down low or mid rev range.:jack
Can some one please provide facts. Or measured dyno results etc.
Thanks.
 
#3 ·
#4 ·
I've got a post buried on here somewhere with a couple of dyno runs with a modded airbox. Some back to back runs with std vs. modded.

No disadvantages anywhere, only advantages. Even with the flapper removed that is supposed to be there for low engine speed (more likely there to keep induction noise lower for EPA drive by noise testing).
 
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#5 ·
Hey guys.
I have looked throught other threads and yes i have seen the 2hp gain mentioned. but what id does not say is where the difference was. If it is at red line and if it effects the running of the bike by being too lean at lower rpm and so makes the bike run rougher then this mod would not be worth doing.
But on the other hand if its 2hp in lower to mid rpm them it is definately worth it.
 
#6 ·
i did mine on just the common sense approach that less intake resistance would increase air flow in. I liked the increase in sound as well. :thumbup
 
#7 ·
I modified my TLS airbox primarily to get rid of the surge at 4000 rpm when the flapper would open. That irritated me greatly.
:banghead

I didn't do the 'full tilt' conversion, instead I merely removed the flapper (aka Intake Air Control Valve) and its vacuum diaphram along with the VCS valve. Then patched the bottom of the "tower" where the vacuum diaphram was.

Honestly, I rarely get to ride in a way where I can appreciate 2 HP one way or the other on a liter bike. However, the improved throttle response made it worth the effort for me. :bounce
 
#8 ·
I just did the 3/4 mod. I removed the flapper and servo, and cut out the transfer port tube the flapper was in. But I left the stock base for the stock air cleaner, which was a bit of a compromise. Then I plastic-welded the bottom where the vacuum servo for the flapper was. Then I plastic-welded a flat external flange of polypropolene 1/8" thick onto the lower airbox, and shortened the horizontal trasnfer tunnel that connects the long ram to the lower airbox by 1/4" and plastic-welded on a flange of 1/8" pp to match the new flange on the airbox. Then I took two button-head bolts with threaded nylon spacers, and bolted them onto the airbox, and drilled matching holes in the tunnel's new flange. That makes two locating pins that keep the airbox and tunnel aligned, even in the event of a backfire explosion. Then I cut out a much larger opening between that horizontal tunnel and the airbox, instead of the stock small "L"-shaped opening. On a previous version I drilled the flanges and laced then together with lockwire, but that's not necessary with a bit of thin insulation sealing foam and the locating pins to keep things aligned.

I usually get 2 hp. But for me, being able to hear the air thru the butterflies as the bike reacts somehow allows me to tell better whether it's rich or lean, and just makes me feel more connected to the engine operation. No dounbt some of that is psychological, reminding me of my old BSA which had only a screen over a large velocity stack.

Oh, and I put in a new stock paper air filter, which was probalby responsible for .5 of that 2 hp increase.
 
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