FCR39 slide UPside down

How I made a total fool of myself :


I know now that its possible to ride a WR450 with the Carburetor slide upside down LOL ;-).   I bought WR450 2005 few weeks ago and have been busy taking everything apart , regreasing and cleaning.


I took the Carburetor apart and did clean it and put everything together and back on the bike.   The bike started and ran but was very rough down at low RPM,  it was either ripping along or I was nearly over the handlebars LOL.   


I started reading everything I found about jetting ,,,,, .  Bought a new needle ,  then a new Pilot jet but still the same.


Ok then I decided to adjust the AP pump,  according to the manual you put some 3.1mm drill or something under the slide and adjust from there.  


I found a drill about 3mm wide and when putting it under the slide , it was impossible to get the slide low enough to even touch the drill.  Hmm I started inspecting the slide and then I noticed the letter "M " on the slide was upside down.  OMG then I relized I had put the slide upside down into  the carburetor when assembling it after the cleaning.


Ok I took it apart , reinstalled it the correct way and now the bike is like a DREAM ,  smooth at start of the throttle and then I can lift the front wheel in 1,2nd and 3 gear.  Good idle and starts instantly.


I stil have a RED FACE but I think its good for anyone to know this if your bike run rough after your Carburetor dissasembly ,  BE sure to put the slide correctly in after cleaning it.


Greeting from Iceland.







Your not the first one. I know a guy in baja that almost went nuts and tried every jet in the book. Until I told him he may have put the slide plate in upside down. He's now a happy camper.

Do a search. You'll find it's been done many times before. At least you figured it out.

I've done it.  I was stumped.  A buddy had to tell what I had done wrong.  He knew, because he had done it before too...

Yes it was a good lesson.  Now I understand the carburator much better and can take it off in 10 min ;-).    

When something changes so drastically you usually only need to go back one step and look real close at what happened before the change.  Which is pretty much what you did with a couple of extra steps thrown in.  Good for you in figuring it out yourself.

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