WR250F 2004 More Power

[1_dirtrider]

I am looking to get a little more power. I have read that there are a few mods that can be done. The bike already has an FMF muffler. I have read changing the exhaust cam to a YZ250F, Removing the grey wire from under the gas tank, changes it to YZ timing, and by replacing the throttle stop with a YZ stop. Has anyone done these mods, and what type of difference will I see.

[Swede73]

I have an 04 and I have done it and so has 90% of all other WR owners. You will see a very big difference.

http://www.thumperfaq.com/free_mods.htm

Follow that link and be sure and do all of the mods. The throttle stop should be first. Right now you're only getting about 1/2 throttle. YZ cam timing you need to grind 1mm off the auto decomp pin and keep the same dome profile. It's very easy to do and took me about 20mins to do start to finish

[ronbuell]

JD jet kit with aftermarket mufler are most bang for the buck after the free mods. The stock muffler didn't work well with free mods for me.... bogged like heck until I swapped out the muffler. Now it runs like the YZ.

[Swede73]

Yeah me too. The modified stock exhaust was better than stock but still didn't run right until I replaced it with an FMF system

[acormier7]

Maybe a big bore. I have all the above mods plus a 290 BB kit and it rips.?

[ronbuell]

Well a 20 % displacement increase can overcome a multitude of sins.

[1_dirtrider]

Thanks for the help guys. Has anyone tried the stage 1 aftermarket cams?

[Swede73]

A lot of guys are running Hot Cams. Myself and a few others are running stage 1 intake and stage 2 exhaust. Very nice power increase throughout the range

[1_dirtrider]

When you Install the hot cams do they both need to be replaced? Also you mentioned grinding down the auto decompression pin 1mm, on the stock wr exhaust cam. Does the auto decompression still work when you do this, and how does it start after?

[ronbuell]

I put a stage 1 exhaust in my son's '02 for the auto decomp feature, works great. You don't grind down the decomp nub with stock timing, only if you advance the stock cam and want to run the E-start. Personally, I do not advance the cam, don't think its necessary. It will loft the front wheel at will in 3rd gear, what more do you need.

[1_dirtrider]

Ronbuell , you only had to purchase the exhaust hot cam, you dont have to replace them both?

[Swede73]

No you don't have to replace them both. If that's all you want to accomplish is auto-decomp then yes just replace the exhaust cam. If your looking for more power then you would probably want to replace both with an aftermarket set. Sorry I know he was asking you Ron but I'm up late and bored so I just chimed in.

As far as grinding down the decomp pin 1mm, it's only necessary if you're going to the YZ cam timing. If you don't grind it then it's tuff to start because the exhaust valve doesn't open as it should. After grinding 1mm and at YZ timing it starts awesome and easy

[1_dirtrider]

Thanks Swede

That is what I wanted to know. So auto decompression, still works as long as you rotate the exhast cam one tooth closkwise. In your opinion is it worth spending the money for the Hot cams or grind the decomp pin 1mm, and changing to yz timing?

[Swede73]

If I were you I would do the grind and rotate and take it out and ride it for awhile. You'll like it. It won't add heaps of power or anything but you'll feel some difference along with the other free mods. It's free so you won't lose much except time if you don't like it. After you've ridden it for a bit then see if you think you'd like the Hot Cams.

[WR250F Captain]

I ran stage 2's, they made a huge difference. loved the top end it gave it.

mega bomb also made a nice increase throughout the rpm range, which is nice but pricey

[Swede73]

If you do choose to go with Hot Cams then Lukes Racing has good prices

http://lukesracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Code=HCYB

You might want to look into Williams Motowerx. His cams are said to give the best power increase without having to go to new valve springs

[ronbuell]

1_dirt / Swede, Swede thanks for stepping in there. I was wiped out from riding in the heat yesterday! Still not feeling well. You got it right, I only did exhaust, but it's on a YZ250F, not a WR, not necessary to get both cams. If you have any questions, call Hot Cams and talk to Steve Beaver 1-515-402-8000. Super nice and helpful guys over there. The stage II is a top end cam only, providing above stock power between 11,000 and 13,000 rpm. I always run my engine slower and then ride the torque curve up, 5,000 to around 10,000. I never hit the rev limiter, save the motor. In my book, a 5000 rpm pull is more useful than a 2000 rpm pull.

[WR250F Captain]

1_dirt / Swede, Swede thanks for stepping in there. I was wiped out from riding in the heat yesterday! Still not feeling well. You got it right, I only did exhaust, but it's on a YZ250F, not a WR, not necessary to get both cams. If you have any questions, call Hot Cams and talk to Steve Beaver 1-515-402-8000. Super nice and helpful guys over there. The stage II is a top end cam only, providing above stock power between 11,000 and 13,000 rpm. I always run my engine slower and then ride the torque curve up, 5,000 to around 10,000. I never hit the rev limiter, save the motor. In my book, a 5000 rpm pull is more useful than a 2000 rpm pull.

my perception of them was no lose in low end torque and good gain in top end... if it did lose bottom end, only a bit, as the bike was easy to wheelie and i don't wheelie bikes at high rpm unless it's a 2 smoke

[1_dirtrider]

5,000 to 10,000 is where I am looking to gain the most power. I ride in the rocky mountains of Alberta/British Columbia. I find there is a lot of logs, rocks, technical arrears to ride. I am looking to get a little snap lower to mid range. Will the stage 1 cams bring the torque curve lower?