Jump to content
Sign in to follow this  

WR250F Jetting

Recommended Posts

Hi, I have an 04 WR250 with FMF Q and throttle stop shortened. I bought it used but was told it had been re-jetted to take account of the FMF. It seems to run ok but last night I thought I'd do the grey wire mod anyway(although I'm in the UK this is a US spec bike). I took it out for a quick ride today to see if I could tell any difference and although I don't think I could when I got back the exhaust was quite black so it looks like it's running rich. If the bike had been jetted for the FMF with grey wire attached would removing the wire cause it to run richer?

Share this post


Link to post
Share on other sites

I don't expect removing the gray wire will make much of a difference in jetting, at least not to be noticed at the tailpipe.

James

Share this post


Link to post
Share on other sites

Ok thanks. As I only went for a short 30mins ride on the road mainly at mid throttle (for a guess) where do you think I should start looking for the source of richness?

Share this post


Link to post
Share on other sites

What are the fuel screw setting and needle clip position?

It would help to know the pilot jet size (#42?) and needle code (OBExx or OBDxx).

The needle clip position may need to be leaned and/or fuel screw turned inwards to get the bike running cleaner.

There are also other things to consider. My '04CRF250R was smoking excessively and the jetting was not rich. The motor, instead, was burning oil from a bad valve seal. In this case, it was using motor oil consistently on every ride.

Try a few carburetor settings staying within a reasonable range from stock and the bike should perform well and run clean.

James

Share this post


Link to post
Share on other sites

Thanks for that James. I suspected you may want that sort of info but never having been inside a carb before I'll need to pluck up the courage first.....

I hope it's not a valve problem as the bike is only 3 months old with 250 miles on it :cry:

I will have a look at the things you mention though

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By SNORE125
      Anyone else have 130 main and 38 pilot jets already in the carb I took the wifes ttr 230 carb apart to add the bigger jets and this bike from 05 that I bought new already had them in it? I was reading that they came with a 125 main and a 36 pilot.
    • By Charles Joseph Miron
      Hello all.  Need a helping hand here..  
      I bought an older TT225 and am not about to spend almost $600 on a new carburetor for it. So I'm hoping someone can help me out with an idea of what (other than original carburetor) style, type and brand I should go with..  I'm also having a bit of trouble finding info on this bike.  It's a 1986 Yamaha TT225.  
      Thank you in advanced
      Charles
    • By Br0ck
      Hey guys, I went on vacation all summer and let my bike sit (2002 CR250). When I got back I ripped it apart and cleaned carburetor and put it back together and it started fine and ran alright, but idled really high. I adjusted the idle screw and realized it was a ridiculous amount of turns out. I can't remember exactly how many but id say 6+ turns out. My killswitch was a POS and didn't work anymore so I replaced it with an oem replacement. My last ride I crashed the bike pretty bad and I was off the bike for 2 weeks. I can't get the bike to start ever since I got installed the new killswitch. I think I wired it right I just replaced one wire at a time and it looked pretty straight forward. I verified it by testing spark while holding it in I was getting no spark but with it in running position it would spark. 
      Anyway I am just looking for some base settings for the Mikuni TMX to get my bike running again, my carburetor has a 35 Pilot and 380 Main jet which appear to be stock. I am located in Edmonton, AB, Canada which is about 2500ft and usually ride between 10-25 celcius.
      Thanks for any replies. 
    • By Goon Rides
      Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.


    • By Zach7018
      So Ive decided its time to pull apart my favorite machine and freshen it up, and I'm looking to make some improvements in the process. I already have a 3x3 mod and a JD jet kit done and it seemed to have changed the world. The stock bike just plain sucked and now its a lot better. I never expect 450 race bike power here but I know there is a little more and I'm wondering if the juice is worth the squeeze. I already plan to add a header and exhaust, an FCR39 carb and stage 1 hotcams. After some research it really seems like those places are where the gains actually come from, so would it be worth it to throw a 434 big bore kit at this bike or just stick with what I already mentioned and a new stock bore top end??? Also my rides are often solo and pretty isolated,how much of a reliability headache can I expect with these mods? 
×