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| Twins Technical Talk Technical Talk for Hinckley Triumph Twins: Bonneville, T100, Speedmaster, America, Thruxton, and Scrambler |
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07-18-2008
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#1 (permalink)
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Member
Supersport 400 Favorite Bike: 07 Bonnie (Goodwood Grn)
Join Date: Mar 2008
Location: San Diego, California
Posts: 99
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Airbox elimination = how much more noise?
I'm considering doing the airbox elimination on my bonnie, though keeping the stock exhaust.
I have two questions. How much more noise can I expect?
And why is the airbox there in the first place? Is it for emissions or less noise or what?
Thanks.
__________________
Mark
And get that gun out of your mouth! -- Sheriff Andy Taylor to Gomer Pyle
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07-18-2008
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#2 (permalink)
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Senior Member
World SuperBike
Join Date: Aug 2004
Location: Stroud, OKlahoma, USA
Posts: 2,339
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The intake "honk" noise is much louder than stock which is nothing I could hear. This noise is not noticeable on mine until the tach hits around 5k rpm. Having said this, I am not sure you will hear any more noise from the intake by keeping the stock exhaust. I am not sure what you will gain by replacing (getting rid of) the airbox and keeping stock silencers. The stock silencers are VERY restrictive--much more so than the airbox, IMHO. I would suspect one would see little or no performance gains with removing the airbox and keeping the stock silencers.
I have read many long write-ups about why there are airboxes, etc. Some of these write-ups were by professed "experts". Some of the "reasons" I remember are: "non turbulent" air for the carbs to draw from; noise; and I am sure there are more, but, I can't remember them at the moment.
I can say this from experience on my '03 T-100 790cc, the bike runs smoother under all weather conditions, idles MUCH better than it ever did stock, and produces lots more HP and torque across the rpm range. Of course, I did not remove the airbox and keep the exhaust restriction--I installed NH Togas at the same time I removed the airbox. I did run some Specialty Spares open exhaust with the airbox stock, and I did get a performance gain with just replacing the very restrictive stock exhaust with much more open exhausts--that is where I draw my conclusion from when I say IMHO, the stock exhaust is more restrictive than the stock intake.
Good luck, mod fever has struck. 
__________________
Larry
2003 T-100 (790cc), NARK, NH Togas, 8100 rpm rev limiter, 158 main jets, 42 pilot jets (less than 1 turn out on pilot screws), stock needles--no shims. 13 A/F ratio from 1100 rpm to 4000 rpm; 12 A/F ratio from 4000 rpm to 6000 rpm; 13 A/F from 6000 rpm to 8100 rpm.:D
2007 Tiger 1050--White:D--SW-Motech crashbars, Skidmarx rear hugger/chain guard, Calsci +7 windscreen.
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07-18-2008
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#3 (permalink)
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Senior Member
Site Supporter Retired Legend Favorite Bike: 904cc Bonnie w/magwheels
Join Date: Mar 2006
Location: Austin, Texas
Posts: 9,166
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+1 ^^^^^^^^^^
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07-18-2008
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#4 (permalink)
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Member
Supersport 400 Favorite Bike: 07 Bonnie (Goodwood Grn)
Join Date: Mar 2008
Location: San Diego, California
Posts: 99
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Quote:
Originally Posted by RedBird
I am not sure what you will gain by replacing (getting rid of) the airbox and keeping stock silencers. The stock silencers are VERY restrictive--much more so than the airbox, IMHO. I would suspect one would see little or no performance gains with removing the airbox and keeping the stock silencers.
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That's what I was afraid of. I'd like to see more horsepower without a lot more noise, and it seems like all the aftermarket silencers are "not approved for road use" and we all know what that means. It's strange, though, because from what I've read there's not really a correlation between loud exhaust and more hp.
__________________
Mark
And get that gun out of your mouth! -- Sheriff Andy Taylor to Gomer Pyle
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07-18-2008
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#5 (permalink)
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Senior Member
Moto Grand Prix
Join Date: Sep 2006
Location: Baltimore, Maryland, USA
Posts: 2,547
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The Staintunes sound great without being too loud. I don't like them loud either, but I do like my Staintunes.
__________________
Marty
2005 Bonneville Blue 790cc, AI removed, Staintunes, Unifilter, no snorkel, 120/40/Thrux needle/1 shim/3 turns, fly screen, tacho, D9 gauge panel, center stand, Ikon 7610s, Hagon fork springs, gaiters, Pirelli Sport Demons, 3 seats.
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07-18-2008
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#6 (permalink)
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Senior Member
SuperSport Favorite Bike: Modified 2005 T100
Join Date: Mar 2007
Location: Rushden, Northamptonshire, England
Posts: 1,305 Other Motorcycle: 1994 CB750
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the stock exhausts are quieter than a family car, how you can want to stick with those beats me, especially if you want more power!
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Every sunday is mad sunday.......
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07-18-2008
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#7 (permalink)
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Premium Member
Site Supporter Powerbike Favorite Bike: British Bikes
Join Date: Feb 2008
Location: UK
Posts: 396 Other Motorcycle: Norton
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With the Nark I can hear my carbs sucking in small rodents, hedghogs and the odd New Forest Poney.... and thats over the noise of them being shot out again by my D&D exhaust.
Combustion = Power = Noise
and thank god for it!

__________________
Red/White o5 Scram - D&D's•NaRK'ed[55bhp]•Lucas Tail Light•Mini Indicators•Mini Speedo
•Polycarb Sproket Cover•Chrome Chainguard•No Side Covers•7" Headlight•Metzier Tourance Tyres..
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07-18-2008
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#8 (permalink)
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Member
Super Sidecars
Join Date: Jan 2007
Location: Peoria, IL
Posts: 42
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Sweat -- about a year a year ago didn't you post something about having fabricated inserts for your K&N's that smoothed out the airflow as it entered the carbs? It seems like that idea is a good compromise between ditching the air box but getting some of the "non-turbulent" benefits back if in fact that is true.
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_____
'06 Thruxton, black, AI removed, TORs, hacksawed battery box and K&N's, 42/142.5's, one shim, 2.0 turns out, tri-bar headlamp with Hella yellow bulb, bad attitude
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07-18-2008
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#9 (permalink)
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Senior Member
World SuperBike Favorite Bike: '06 T100
Join Date: Jul 2006
Location: Republic of Texas
Posts: 2,494
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Quote:
Originally Posted by Baltobonneville
The Staintunes sound great without being too loud. I don't like them loud either, but I do like my Staintunes.
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I'll second that notion.
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Phil (road dog)
Click on the Image for Larger Picture
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07-18-2008
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#10 (permalink)
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Senior Member
SuperBike Favorite Bike: 03 T100 989
Join Date: Mar 2007
Location: richmond va
Posts: 1,572
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OPEN BOTH ENDS UP AND LET HER ROCK.You will know when its right when people start leaveing letters in your mail box like i got today telling me how much my bike messes up the hood lol.Asking me not to ride up my road lol.Well I got a contract on my house see how they like the shopping center there going to build here lol.Before i move i am going to throw the biker party from hell lol.Get all my buddys with hds with drag pipes to go for a ride up and down the street lol.
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Why do I feel young on my bike
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