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Stock Exhaust Modification on 2013 WR250F

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I'm kind of unclear as what to remove from the exhaust at this point.  Maybe it's just confusion from reading so many different things, but after seeing a dyno comparison of a stock exhaust vs. one that has a GYTR tip and a stock with tip removed it doesn't appear this does much in regards to power.

 

The only thing I'm doing at this point is pulling the snorkel, clipping the grey wire, and then doing the JD jetting & O-ring.  Does the exhaust even have to be fooled with?  If the tip is removed will it still pass a db check?

 

My goal is to make this bike kind of like a modern KDX200.  It's got less than 2 miles on it right now.

 

Thanks

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I have used the jd kit on my 2012 wr250f when i just did the free mods and removed the inner baffle, which i did notice a bit more power as it still felt restictive due to the "quite tip design"...i then used the gytr tip and noticed a way better increase in power and response and still will pass sound check... i was gonna modify the gytr tip a bit more till i had the money saved up for an fmf slip on but then i came across a brand new pro circuit t-4 slip for a steal at $200 less than a week later... havent looked back yet...

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I have had 2 WR's , current is an 07'. I went down the modify stock tip, GYTR tip and finally drill baffle. If quiet is your goal its fine if you want more seat of the pants grunt an after market exhaust fits the bill.

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I have a 2013 WR250f.  To get this bike to run right take the end cap off to get to the first baffle.  Unscrew the 4 allen head bolts and take the entire baffle that has the snorkel on it and through it away. You can reinstall the spark arrestor, then reinstall the end cap. Use a JD jetting kit and use the recommended settings for a free flowing exhaust.  The noise is about the same as a FMF Stealth Q exhaust.  You still have the second baffle that's  at the front of the silencer. This makes a dramatic increase in power especially at low rpm with only a small increase in noise.  You don't need to spend money on an aftermarket exhaust.   

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Cool deal Bliz, that's exactly what I was hoping to hear.  I thought it was going to be really loud without the last snorkel/plate.  Thanks everyone!

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Cool deal Bliz, that's exactly what I was hoping to hear.  I thought it was going to be really loud without the last snorkel/plate.  Thanks everyone!

Personally I thought my bike sounded awfull with the just the spark arrestor. The WR muffler is a series of un aligned baffles that restricts flow / noise (restriction & cancellation to reduce noise). Aftermarket mufflers have a packed perforated core to absorb noise yet allow free flowing exhaust.

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I'm trying to avoid laying down $330 bucks on an exhaust right now.  How did it run?

A modified tip would increase the flow w/o noise. If you don't mind the noise or ride in a noise restricted area you could run just the arrestor. When I purchased my WR a fellow rider asked if I had an extra 1k dollars budgeted for my purchase ??? He meant undoing all the emission corking would add up quick... Jet kit, exhaust, camshaft etc.

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Well if my jet kit comes today and I can succesfully install it I can check out both ways at a track tomorrow.  Is changing just the main jet a pain in the ass?  Track is probably 1000 feet, maybe less but where I'll be going is 3000-6000 feet depending - Stoddard Wells, Arrowhead, Lucerne.

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Removing the second baffle does not make the bike overly loud. You still have the first baffle in place.  The only expense you have is a JD jet kit which is about $75 and is worth every penny.  If you're patient you can install the JD needle, main and leak jet and oring without removing the carb. JD  provides an oring to put around the accelerator pump linkage that increases pump pressure. Took me about 3 hours to do all of this.  Took forever to remove the float bowl screws, but I still think it's easier than trying to get the carb off.  If I remember right my 2013 had a plate over the fuel screw which had to be drilled out before I could adjust the fuel screw but once you have the float bowl off it's not hard to drill out. At first I just did the jet kit and removed the inner snorkel in the exhaust outlet.  Bike still did not have much power off the bottom end.  Removing the second baffle and then adjusting the jetting again make a big difference without making the exhaust too loud.   

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I owned a 2009 WR-250F (and, as mentioned, a WR-250F is the same machine from 2007 to present) and ran the stock exhaust muffler and header pipe for a while.

 

Straight off the showroom floor, it is so choked-up the bike will basically barely run, and it literally feels and sounds like somebody is holding the palm of their hand over the muffler outlet.

An obvious EPA compliance situation.

 

With the pencil-sized "pea shooter" insert removed from the tip, it feels like a typical street-legal muffler on a Japanese dual-purpose bike:

Still pretty choked-up, but at least you can ride the bike, and the exhaust noise is still as whisper-quiet as a luxury car.

 

With a hole drilled in the rear baffle chamber wall, there is a little more power with a little more noise, but I don't remember feeling or hearing anything dramatic - it still felt choked-up and sounded like it.

 

Replacing the stock header and muffler for an FMF Powerbomb head pipe and Q4 muffler was like somebody flicked a switch.

Gone was the choked-up feeling, and in it's place was a machine that felt like a modern $6,000-plus dirt bike.

There was more noise, but it was not objectionable, obnoxious, annoying, or anything that made me feel bad or guilty for running it.

In fact, it sounded like a finely-tuned performance machine that was muffled enough.

Power and throttle response felt much better, with a noticeable increase in low-end torque.

Simply put, the bike felt liberated from the potato stuck in the muffler.

 

Through all of this, the bike had all of the typical "free mods" along with the GYT-R AIS Removal Kit (AKA: parts to rejet the carburetor).

 

In other words:

If you need to be as quiet as humanly possible, the stock muffler with the "pea shooter" removed will accomplish that, but too bad you need to use the bike in such a restricted form.

If you are able to ride the bike in an area where you are not made to feel like you are committing a crime for riding a still-reasonably-muffled dirt bike, an FMF Powerbomb header and Q4 muffler is worth it.

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