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yamaha 2003 wr250f specs

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Yeah, the 250F  is a screamer.  It has mid range torque, which is where I like to ride it.... between 4000 and about 11,000.  It has over rev up to 12,500... which is where the racers run.  I hate hearing bike run on the rev limiter, so I don't run mine that hard.

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well its all stock engine wise, I could probably take one of the air filters out (because for some reason it has two on top of each other), take the snorkel out, remove the pea shooter baffel. But I see pros with stock wrs climbing log hills, deep mud, very tricky terrain with stock wrs, so I think ill just leave the exhaust and intake alone because I like the enduro style anyway I just got to get the wr plastic... But can you tell me if removing the exhaust baffel will unleash THAT much power because I hate it when oldys non motorcyclist mess with me over noise, thanks.

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This is what you do to get performance from these bikes.  Get a YZ 250F muffler off of eBay from an 03, 04, or 05, and add a spark arrestor to it.  The stock muffler has a spark arrestor, but the muffler has a flat plate in it which destroys power.  It will bog and not develop the power you seek.  Then remove the snorkel in the airbox top.  That will allow more air thru the engine.  To fix the jetting, you need to order a JD Jet kit.  JD includes a needle for high elevation and one for low elevation and jets with great instructions.  Next you need to do the gray wire mod.  This is to allow full advance of the timing curve to YZ spec.  Find the gray in the wire harness that plugs into the ECM.  Remove it from the plug and tape it up. You can use a small pic or small screwdriver.  Last, you need to shorten the throttle stop on the throttle to allow full throttle.  It needs to be about 17mm long.  Its on the back of the carb housing where the cable cover is located.

Leave the dual foam air filter.  That is a plus.  This is not a two broke.  TwinAir filters are an upgrade! Keep it clean and make SURE that it is sealed to the front of the airbox.  Use filter grease around the seal to seal it up.  Dirt getting sucked thru destroys the intake valves, very expensive to replace.  Use a cleaner to clean the filter, rinse it, dry it, use BelRay air filter oil in the bottle, not the spray.  Put the filter in a 1 gal zip lock bag, pour oil into the bag, and work the oil all thru the filter.  When it all turns blue, you're done.  You can wring out the foam and save that zip lock bag with left over oil for next time.  Then get another new filter and keep it on hand so you can swap them out.

Keep track of the time on each oil change.  I use an engine meter that records run time.  These bikes only use 1.25 qts of oil.  It gets broken down within 5 hours of run time.  Change oil and oil filter at 5 hrs... do not go over that time.

Read ThumperTalk for these and other pointers.  There is literally a ton of info on here.

Edited by ronbuell

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Ron Buell....   for the umpteenth time, would you F**KING PLEASE stop telling ppl to buy those LOUD YZF mufflers for their WR!!!!!

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Depending on riding conditions and riding style, personally I think 5 hrs is early. I go between 10-12 with regular trail riding.

As for mods, you may also want to try the "o ring mod". Helped my WR.

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6 hours ago, BazookaJoe said:

Ron Buell. ...   for the umpteenth time, would you F**KING PLEASE stop telling ppl to buy those LOUD YZF mufflers for their WR!!!!!

The YZF muffler gets my vote too.  First thing I did to mine.

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I did all the mods that ronbuell recommended but I can't afford a yz muffler right now will these mods still work without that

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In a word......  NO.  The stock WR muffler is not a straight thru design.  I don't know, but I suspect that the design sets up a reverberation or  pressure wave that, at the right rpm, actually reduces power.  Every one I've had bogged at a certain rpm until I replaced the muffler.

A free flowing exhaust is what turns all the rest loose.

And no, you don't have to use a YZ250F exhaust.  I only mention that one since its available and is an economical way to release the power and throttle response you want.  I've tried Akrapovic, DrD, and others, but I get the same results cheaper with a modded YZ muffler.

To Joe's point above, yes, they are louder than stock and than other accessory mufflers.  I remove the end cap and add the sparky and when I do that, I pack in more fiberglass and pack it tight.  The pipe I liked the best was the Akrapovic.... best sound of all of them.  It was mellow and didn't bark.  I hated the rear mount, and sure enough, it broke and destroyed the muffler.

Maybe BazookaJoe will buy me one.

Edited by ronbuell

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hey guys I took ronbuell's advice and bought a yzf muffler and it made a huge difference the bike went from underpowered 250f to a scary fast mean son of a bitch..my point is ronbuell was right, what he told me to do turned my bike into a dirt crotch rocket..if he gives you a suggestion listen to him.

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