I bought a 2006 WR450 a few months ago. The bike was in pretty good shape, but the previous owner didn't do so well with the jetting and modifications. I have spent several hours searching through threads and though the bike runs pretty good, there are still a couple of discrepancies. I still have popping on decel. Here is some history on the bike. When I got it the bike had the stock jetting with a 170 main jet, and AIS removed. The exhaust
was completely gutted and other than that, the bike was stock. After a bit of work I went up to a 50 pilot jet, 168 main, needle clip stayed the same (3rd clip), fuel screw at 1.5 turns, and I also bought the GYTR needle that comes in the AIS removal kit. I also installed a GYTR exhaust baffle since there wasn't anything on the back of the exhaust can other than the cap that attaches to the back (hopefully that makes sense) and did the airbox mods. Took it for a ride and still had popping on decel along with a horrendous bog.
After somemore research and brainstorming I installed a R&D powerbowl 2 (fixed the bog) and a FMF
4.1 slip-on. I also increased my jetting to a 170 main and ended up progressing up to a 60 pilot and moved the clip down one to the 4th position, fuel screw 2 turns out. Though the popping got a little better, it is still present. Both exhaust configurations rendered the same results. So I'm ruling out the exhaust. I have checked my AIS points and everything appears to be done properly. I have been through the carb and the slide and other mechanicals appear to be in good working order. I ordered some new gaskets and little nickel and dime stuff last night while I have the carb off, but here is my question:
The elevation where I live is about 600ft. Is there anything I'm overlooking? I'm assuming that it is more than likely my jetting, but I'm almost at a loss. Would I be better off buying a JD jet kit, or is there anyway to deal with what I've got? I have jetted plenty of bikes (almost all Yamahas), but this one is absolutely kicking my butt. Any help is much appreciated.
***Also, I forgot to post***
when I pulled the carb back out of the intake boot, I discovered that when I twist the throttle I am not getting a AP squirt. Would the Powerbowl disable that or do I need to be investigating further?
Edited by crash279, April 13, 2012 - 07:00 AM.