WR250F - need to uncork it and make it rideable

Finally found a WR, bone stock, corked up as they all are.

I have to make a few mods to bring it to life. Here's the short list of what I'm planning to do.

YZ Can

12 tooth front sprocket

gray wire mod

AIS Removal / JDY011 Jet Kit (+o-ring mod)

Open Air Box

Longer Fuel Screw

YZ/drill Throttle stop

Boyesen Quick Shot 3

New fork/shock springs to fit my weight/riding

Anything I've missed, or any better options than the above ?

Woods riding and in general a fun bike with maybe a local club race once in a while


If anyone happens to have gone to an aftermarket exhaust on a YZ250F and the you want to sell the stock can/pipe please PM me with details



Edited by LoneStarKTM

With the exhaust and while you're waiting for a new one, remove the baffle and drill holes in the front baffle with a long drill bit. It's not as good as a YZ exhaust it's still better than the stock WR exhaust. Are you going to replace the exhaust cam or do YZ timing?

I've had my dealer uncork the last 2 WRs I bought from them. (usually) Alot less hassle.

With the exhaust and while you're waiting for a new one, remove the baffle and drill holes in the front baffle with a long drill bit. It's not as good as a YZ exhaust it's still better than the stock WR exhaust. Are you going to replace the exhaust cam or do YZ timing?

Initially I'm going to go with the gray wire mod for the YZ timing.

One of my good long time riding buds has an identical bike with the above mods and he has just received a set of YZ cams. He didn't go with Hot Cams or the equivalent due to pricing. The YZ cams were $90 for the set, so, he decided to give them a try and see what results he gets.

If he gets decent results, I may go that way too. If not, I'm going to ride my bike a little and see how I like the power on it with the el cheapo mods before deciding on cams.

I've read your comments about the stock WR cam being 1mm different than a YZ cam. I haven't taken the time to research exactly how to properly remove 1mm from a cam lobe, so I have some reading to do. I like that idea best, but I need to actually ride the bike first :confused:

I picked it up last night right at 10:00 PM and it's almost 5:00 AM now, so I'm getting a little itchy to ride it. Of course, it's raining cats and dogs outside, but, I've been wet before :worthy:

One of the riders in our club swears by the Rekluse (sp?) auto clutch and the Scott's dampeners. Those are big ticket items for my now deflated toy budget and I don't know which dampener or if I would get used to an auto clutch or not. I've been riding many moons without an auto clutch, but, I'm told they're sweet for gnarly woods riding which is my favorite.

My first semi-costly change will be the suspension as I think that is more important (for a rider of my (lack of) skill level) than an auto clutch or dampener until I can rake in some overtime and replenish the toy budget.

I've got an hour meter which I think will be all the electronics I need for a play bike.

I'll know more after I ride it a few times, but I'm thinking uncork it, get the suspension dialed in and then see if I need to do anything else.

I *do* like the idea of a nice set of cams and an over bore when it's time for a rebuild for certain though :thumbsup:

Can you school me a little on the best (proper) way to remove 1mm from the WR cam without hosing it up ? I'd really like to gain some decent performance for a little machine time.

I have never held a WR or YZ cam in my hand so I don't know what I'm looking at. I've done several LC4 cams over the years and a (cough, cough) Honda cam, I assume there isn't a whole lot of difference.

I am curious to pop the cover and check out the Yamaha setup. I do want to ride it a few times before I get into setting up the Bridgeport, but if I can go with shaving a mm off a cam lobe and see some performance increase, I'm liking that cost savings big time :busted:

Edited by LoneStarKTM
correct spelling

Oh you don't grind off the lobe!! The auto decompression mechanism is a spring loaded little stub that comes out at low RPMs and once the bike is started centrifical force makes the pin recess back into the cam. Once you have the cam cover off you will see what I'm talking about. Take the cam out of the bike and on to the bench. A dremel tool works best with a hard polishing stone, I found, worked very nicely. Anyways, measure how tall it is with a micrometer or digital calipers and grind off a little at a time till you took off 1mm then round off the top to make it a dome shape as it was originally. Wipe it down and install it. WR timing there is 13 pins on the cam chain between the punch marks and YZ there is 12. So basically you are going to rotate the cam clockwise one tooth. I am pretty sure there isn't any difference in cams between the YZ and WR except the timing. You gotta do it man!! You just gotta!!!!

OK, now I gotta go rip the cover off and look at it.

First ride isn't until Sunday - if it quits raining.

It's been sitting here, bone stock for over 9 hours, time to fix that :thumbsup:

One quick question... do you have to remove the sub frame to get to the carb ? :confused:

I can't see another way to get it out :thumbsup:

No need to take the carb off. You can get to the needle from up top and the pilot and mainjet through the access plug in the bottom. I used an 09 YZ250F needle in mine.

Don't waste money on a slip on for the WR. It has a smaller headpipe. I'd get a full exhaust for a YZ.

A full system for a YZ250F will fit a WR ? :thumbsup:

Not to expose my newbie ignorance in a roaring blaze, but if the YZ250F stock system will fit a WR250F, would it also be plausible to look for an aftermarket full system/slip on for a YZ250F with the intention of putting it on the WR ? If so, any idea what year range will fit a 2009 WR ?

The reason I ask that way is there is a local shop that isn't a dealer, but they deal in just about every known MX/offroad accessory known to man. They are cheap and everyone I know of deals with them for misc parts and items that the dealer either doesn't carry or prices at full retail.

One of the cool things about this dealer is they do a bulletin board swap thing once a month. This is where customers can bring anything they might want to trade or sell and it's a straight customer to customer sale/swap kind of thing. I've been to it a couple of times and I've seen a metric ton of YZ250F parts and pieces from various year models. Sometimes there will be a bike getting parted out right there on the spot etc..

As you can imagine, some things are a steal (if you need them) and others are nothing close to reasonable, but if a YZ250F exhaust will fit on a WR250F, I will run out there this weekend and see what I can find. I've been scouring the net for WR250F specific exhausts as most mfrs of aftermarket pipes/cans offer a different product listing for a YZ and WR 4T offerings.

I feel pretty sure I have a better chance of running across a YZ system or slip on used than a WR system.

I used a stock 06 YZ250F pipe on my 07 WR for a while and the bike ran good with it.

I don't know what years the YZ250 pipes fit. I think it was 06 to 09.

I'm sure you can find a deal on a stock pipe or an aftermarket pipe used.

eBay is full of them. Buddies have run Dr D pipes with pretty good success.

As long as what you get has fresh packing in it you'll be fine.

I drilled the exhaust (thanks Swede for the tip :confused: ) and removed ~1mm from the decomp stub and unhooked the gray wire and got the JD kit in it and added a YZ throttle stop.

I went with a 180 main, left the leak jet stock and decided to go with the blue needle in the 4th position. There is still a slight bog, right off idle if you blip it, but I understand that to (possibly) be the leak jet. I've got a Quick Shot coming, so I decided to leave it as is for now.

The exhaust holes look kind of ghetto, but it made a noticeable difference. One thing is for sure, this little thumper will rev to the moon :thumbsup:

The suspension is still stiff from being new, so it feels pretty good. I checked the fork oil just for grins and it was up to snuff. I'm sure as it breaks in a little things will soften up some. Springs are on the way, but won't be here by this weekend, so, I'm probably going to ride it easy.

I'm going to check the swingarm and wheel bearings tomorrow and grease if necessary, then change the oil and I'm ready to go.

Woo Hooo!! You did it!! Yeah the holes is ghetto but hey, it's free. Did you ride it all corked up before the mods? Can you tell the difference? Did you open up the airbox yet?

Ghetto+free that works is OK in my book any day of the week :thumbsup:

I did ride it bone stock for about ½ hour to warm it up a little before I went over everything with a torque wrench. It felt amazingly like a warmed up 230 CRF.

If there were no mods to uncork it, I would be pretty unhappy with it.

I could definitely tell a difference. I did the needle and jets (180 main and 40 pilot) and it was running a little rich and felt like it was about to sneeze every time I hit the throttle.

I got back to the house and cobbled together a drill extension and drilled a couple of 10mm holes, right in line with the second baffle vent, just to the left of the pork chop. That seemed to improve things noticeably, so I drilled a few more. The magic number on how many holes make a difference is 6-7.

I yanked the snorkel and (also ghetto) drilled a few holes in the side cover and covered them with some fine mesh screen. I'll cut it out properly when I get the new can.

I can power up the front wheel in 2nd from a roll now, but not 3rd. I figure the new can and the 12 tooth CS should help that.

The stock suspension feels pretty good as it doesn't push at all on the front end in corners and the bike is easy to steer out of corners. I didn't go over anything ugly as the closest place to ride is mainly a power line road that runs by a river. Some bumps and tricky spots, but nowhere near a full workout in gnarly stuff.

The stock tires are OK, but I'm thinking a change to a Maxxis or Pirelli will be happening pretty quick.

The main is a little fat as is, and I might go to the red needle just to see if it sharpens it up a little, but I'm going to leave it as is until I find a can...

So far so good :confused:

Yeah that's what I did to my airbox on the right side was cut out the silhouettes but on the left side I installed about 8 round 1" Uni-Filters and it works great.

Nice to see someone happy. IMO I wouldn't bother with the 12 sprocket....way too hard on the swinging arm. You can run a 52t rear with the stock chain. Just 'slot' the 3 holes that mount the chain guide which will allow it to drop a bit further. A 40# leak seems to work in most cases. Enjoy.

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