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To Anyone With Aftermarket Exhaust...

187698 Views 358 Replies 291 Participants Last post by  GASoline71
Maybe we should start a compilation of jetting specs according to exhaust type, mods. and location...might give other members a place to start when modifying their bikes. Just a thought...I'll list mine soon as I get home from work and figure out what they are, exactly.
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May 1 2010 Dyno at Little Sahara
Above is a link to copy of dyno run with a 175 main, 48 pilot and clip on #4, it ran very good but had some roughness and was a little rich so I am now running 168 main and 45 pilot with clip on #3 and all roughness is gone and rpm's build much faster than before. Do not have dyno chart for this setup right now.
i just bought a 07 its stock except for a gytr oval slip-on. air box lid on. 500ft above sea level. it is jetted 45p 170m and i belive stock needle. when it get is the high rpm or 4/5 gear it breaks up real bad. do i need to go up on my main or adjust the needle
2008 Yfz 450

cam mod
zip tie
JSR 9 Inch can
Fuel Customs
15 tooth front sprocket


Needle NVCQ 4th clip
Pilot- 48
Air Screw 2 1/4 turns out
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Well if you all have aftermarket pipes... Why cant I find a stock one for an 04 .lol

Any one having any problems with this Leo Vince exhaust? I been having problems with it turning blue witch means its rich. But Also gets so hot that it melt the shed guard off and then I warped it with exhaust tap. It is a titanium, the pipe is set right now to stock settings. It some times back fires. I also have have valves sticking problem and brought it in for a valve check and they found all but one valve moving. they relay placed it. I still having problems with the exhaust and back firing. Spit and sputtering, shitty throttle response. Help? anyone!........................
-UNI 2 Stage
-172 main
-48 pilot
-2 Turns out
-3 clip from top
1700 ft above
washington pa
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2008 yfz 450

curtis sparks exhaust
esr intake
zip tie mod
13 front sprocket

175 main
45 pilot
3 clip from bottom
2 turns fuel screw
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1300 ft elevation
Yoshi full exhaust, Tri oval carbon fiber.
Quad works filter, NO lid.
Zip ty Mod. R&D Remote F/S 2 turns
165 main, 45 pilot. Stock needle 3rd clip.

Going to do the cam mod soon, then i'll play with the jetting again
Good thread, This helped me out a lot, can't wait to ride now!
eddie sander racing pro series exhaust pipe, esr cdi box, esr intake, needle jet. best upgrades very loud and very fast
HMF slip-on
ESR Intake
12.5:1 CP piston; zip tie mod; cam mod
175 main, 48 pilot, 35 leak, NVCQ 4th clip, f/s 3 turns out
Muzzy slip-on stock air box with uni filter elevation 3000 feet I am currently jetted at 168 main 45p stock clip at 5th clip, no cam mod yet. :red :sonic
'05 YFZ @ 600 Feet

- Trinity Stage IV Full Exhaust
- Cam Mod
- ESR Filter (Aluminum Airbox w/o Lid)
- 178 Main Jet
- 48 Pilot Jet
- NVCQ 4th Clip
- Fuel Screw 2.5 Turns Out
i just bought a 2011 yfz450r im am between a couple exhaust i really like the full barker system and since my quad is efi i do not need to jet it correct? any help would be great
No you don't need to jet it. You don't get a carburator with the fuel injection =D
I live at 800ft above sea level running an alba header and gutted stock can. K&N wit proflow and outerwears with no lid. (2007YFZ) Where should I be I cannot get it right the guy I bought it from had it all messed up because he had no idea what he was doing. Now I have a horrible bog on bottom end but if you ease into the throttle it does fine (with a little poping). HELP! I need leak, main, pilot, and screw settings any suggestions?
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