450 RFS carb question..... Starting with a Baja trip in March, my air screw requires 4.5 turns out to idle and run without severe popping on decel. Last night I pulled the carb completely down and blasted carb cleaner and compressed air thru all the passages and jets. Put it back together and nothing changed. Fuel screw is aftermarket and inserted correctly (O-ring, washer, spring, screw). It runs great, but I worry about the screw falling out if I get too far out.
Think I found the problem: http://www.thumpertalk.com/topic/50719-ktm-450exc-fuel-screw-problems/ Need to pull the slide & check the plate orientation. I had it apart during the winter rebuild and probably put it back together wrong.
If it does vibrate out somewhere in bfe plug the hole and you can finish your ride, won't run great but it'll run.
I carry a spare. During the rebuild I lost the spring, and you can only order the spring as a kit with the needle. I recall the slide surprising me by falling apart when I removed it. I scratched my head over the proper orientation to put the plate back on. Given a 50/50 chance, I guessed wrong. I'm 99% certain this will fix the problem. The description of the issue on TT matches my situation perfectly. IMO, it should be an engineering felony to release a design that allows critical parts like this to be mounted in multiple orientations.
All engineers are a bit felonious in that regard, too bad there wasn't a good technician handy to tell the designer how to make it idiot proof
What year is your RFS, and are you the first owner? BTW, "Wisdom is knowing when to avoid perfection" Kilgore Trout
changing out the pilot jet is pretty easy.... 42's seem to work good on everyone i've seen.... 40's are a bit lean.... but i'm at sea level too, so.....
I put an FCR39 in my 640, put in a Dynojet kit and forgot to adjust the fuel screw to there suggested setting, and couldn't be bothered pulling it out again to change it. The thing ran pretty ordinary and would die at random times when idling and was a pain in the ass to start. I was doing some other work on it a few days ago and decided to adjust the fuel screw and got a bit of a surprise to see it was missing.:huh I fitted the fuel screw out of the old BST in it and she runs and starts great.
Bike is 2006 450. I flipped the slide plate last night and all is back to normal. The orientation is non-intuitive. The parts diagram shows the correct orientation. I can't believe that I've ridden 1k miles with it like that. Other than having the fuel screw way out, it ran just fine.
