Customizing my WRR

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Great info regarding the CO adjustment

Traveller, since you have a o2 sensor what does the screw on side of throttle body do add air or gas, at idle only or everywere

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Looks good

But why bother keeping the exup setup? It does nothing to help power, if you have a programmer to get rid of the lean spot low to mid throttle. When stock and leanish until your wide open, the exup adding back pressure would help as having a good a/f ratio is better than a free flowing pipe with a lean a/f ratio but if you can richen it up it's hurting power. The exup is open at low revs/throttle then closes while your twisting the throttle in the mid revs to keep the bike quiet to help it pass sound test then it opens back up so it doesn't kill the top end power, some guys think its closed at low rpm to help power but its not.

I went from a fmf Q4 to a stock pipe with the exup unhooked and welded open as I lost some of its parts, the bike has plenty of low end, more than stock in fact as I still have the opened up airbox and fmf programmer, those mods add some low to mid power. My neighbor has a stock wr250r to compare to, mine has more low end and mid range power than his.

With my exup missing the spring that holds it open and flopping around I tried the bike with it opened and closed by holding it with small vise grips. With it open the bike runs good with my programmer and modded airbox, with it closed the bike bogged at 1/2 throttle within 20 feet of my house and I turned around so that was the end of testing it, its staying wide open.

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Just look at the many dyno charts. Opening up the intake, and adding a full exhaust system and a powercommander shows gains everywhere thoughout the rpm band.

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I don't know where you got that BS about the exup buts its not true.

The exup is open at low revs and closes a bit at 3-5k to make it quieter, the stock efi is tuned to run with it blocking the exhaust off a bit so your lean and lacking power with stock efi and no exup but with a programmer and no exup you will have more low end power than stock.
Wide open straight pipes make the most low end if the tubing is the right size (about 1 3/4 or 1 7/8 on a 250)baffle's kill the scavenging hurting power.
Heres a video of the exup in action.https://youtu.be/sPeBawoIXAM

The wr250r has small camshafts compared to offroad 250 four strokes, they make more tq and don't use fancy exhaust valves, if they helped don't you think they'd be on more bikes?

Also you should check out dyno reports, they show gains in the 3-5 k range with open pipes, infact that's where you notice the modded bikes pulling way better than stock.

Fixed it. Going riding this weekend.