WR 450 jetting BOG PROBLEMS


Well, I've Listened to my brothers freind and did the following.

I took off my QSII pump cover, installed a smaller leak jet#40, larger main#168 and pilot#48 to get rid of the bottom end bog or stall in the throttle, I also put in a ziptie fuel screw and well all this made it worse. alot worse in fact. I already have a fmf powercore muffler on, and well like I said, it got worse. In fact, when going down a long hill under compression now I don't really have any hold back from the motor, and I am getting alot of poping and flames out the muffler...I think the pilot jet is too big. My bike never did this before. when I would let off on the throttle, it was almost like hitting the brakes, and it never made the popping sound or shot flames out the muffler.

That being said, I'm going to put the QSII cover back on, put the #165 main back in and the #45 pilot back in. I will leave the #40 leak jet in because I've seen diagrams and the smaller one does make sense. My needle has been in the 4th slot from the top since I got the bike. I never changed it's position. I'm not sure if you can ever get the throttle on one of these to be as responsive as a 2 stroke like my brothers freind said his was without going to fuel injection. (by the way, my brothers freinds bike is actually a little worse than mine)but it would be nice to get as much out as possible. Does anyone out there have any suggestions on this subject. the way the bike was, wasn't too bad, the bottom end would catch me off guard now and then when I got screwed up at the bottom of something and had the motor pretty much down to an idle, but other than that, it was a monster.

Thx, and I'll be looking forward to what you have to say....good or bad...lol


Edited by BANSHEE
wrong title

get a jd jetting kit e-mail them before installing it and give him elavation and mods, fixxed my wr450 95% its an 04 170 main ,stock pilot and needle on 5th clip fuel screw at 1 3/4 turns out

Thx, I'll mail them and give it a try

Did you oring the AP linkage or install a stiffer AP spring?

Did you confirm the AP was squirting?

Did you check/set the AP timing?

Consider a YZ needle instead of the JD kit. If you have the money to blow then be my guest, a lot of people like the JD kit. I found YZ needle worked great. My JD needles are on a shelf. William1 has a good suggestion before you spend a dollar.

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