Put the expansion chamber exhaust and its slower

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BOREDTrackRacer

BOREDTrackRacer

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Nov 10, 2009
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Put on the expansion chamber exhaust and its actually slowed my bike down, and its sounds crappier too. I had a stock exhaust on it, with the cap off, stuffed with steel brillow pads and it sounded great and ran great, really torque and had good top end. After putting the expansion chamber on, it sounds worse and I feel like I lost that torque, but the top speed seems around the same. Has this happened with anyone else??
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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Ya might need to rejet/adj. air/fuel mix but what's more than likely is the change in sound is messin' with yer head.

If it wasn't for my GPS tellin' me otherwise I woulda thought the same thing - when I extended the silencer on my SBP system and quieted it down, my brain told me I was goin' slower... but in fact I had exactly the same performance as before *shrug*

Oh right, when it comes to exhaust tone, "sounds better/worse" is purely a matter of opinion lol I fer one hate the ghetto sound of a cap-less stock pipe ;)
 
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BOREDTrackRacer

BOREDTrackRacer

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Nov 10, 2009
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Los Angeles
Its the spooky tooth expansion exhaust. Im pretty sure its not the placebo effect. My capless exhaust actually sounded really good.. I agree the capless sounds like crap, I have ran it like that myself and have friends that run it that way, and we all agree is sounds bad.

However, stuffing it to the brim with the steel wool pads and putting a screen at the end made it sound REALLY good. Has a very low tuned sound to it and has jerky torque to it.

I have the slanthead with the performace carb, but have an old small air filter on there. Could putting a less restrictive intake help? By rejetting do you mean adjusting the needle?
 
BarelyAWake

BarelyAWake

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Hmm... I dunno about the Spooky chamber (lol, that sounds cool tho), there's not been enough feedback on the forum for me to give ya specifics... I've the SBP one and it was a night and day difference over stock capped/uncapped, but I did hafta tweak the carb a bit too.

Yeah - I'd suspect restriction from the filter and as for the carb - yeah needle settings. The plug color will tell ya what it needs better than I can anyway heh
 
longhair

longhair

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Mar 24, 2009
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eagle rock
BOREDTrackRacer said:
Put on the expansion chamber exhaust and its actually slowed my bike down, and its sounds crappier too. I had a stock exhaust on it, with the cap off, stuffed with steel brillow pads and it sounded great and ran great, really torque and had good top end. After putting the expansion chamber on, it sounds worse and I feel like I lost that torque, but the top speed seems around the same. Has this happened with anyone else??
Click to expand...
Hey B Tracker, I put an expansion chamber on one of my stretched bikes and it actually gave the bike an instantanious increase in speed by 3-5 mph. This bike now does right under 35mph and have clocked myself several times with speedtrap {Chevy Chase Dr.} and car. It's important to position the expansion chamber at least 12" from the pipe connection at MB motor head. I also use an exhaust form a pocket bike that runs all the way past seat down by tire. Good Luck
 
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