Need some guidance ****updated****

[crash279]

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 April 13, 2012 by crash279

[Just_a_trail_rider]

There is a jetting guide at the top of this forum. Take a look.

What the JD Jetting kit does, more than anything is tell you exactly what to do.

What you have setup... it will never work at that elevation.

I ride at 6K feet all the time. Your pilot jet should be a 45. Your main should be a 165. Fuel screw should be 1.5-2 turns out. Then play with your needle. That is your starting point.

Or buy the kit.

[crash279]

There is a jetting guide at the top of this forum. Take a look.

What the JD Jetting kit does, more than anything is tell you exactly what to do.

What you have setup... it will never work at that elevation.

I ride at 6K feet all the time. Your pilot jet should be a 45. Your main should be a 165. Fuel screw should be 1.5-2 turns out. Then play with your needle. That is your starting point.

Or buy the kit.

I started with a 45 and I had this same issue. It did get a bit better as I went up on my pilot. I did read and in fact print out the jetting guide. Also, I'm at 600ft. lol.

[MANIAC998]

How is the exhaust gasket? If the gasket isn't new, and in fact, was re-used upon re-installation of the exhaust, that alone could be your problem. That will definately cause a lean "pop" on deceleration. Maniac

[crash279]

How is the exhaust gasket? If the gasket isn't new, and in fact, was re-used upon re-installation of the exhaust, that alone could be your problem. That will definately cause a lean "pop" on deceleration. Maniac

I looked at the gasket and didn't see any evidence of a leak. However, I just ordered a new one just to be sure.

[Just_a_trail_rider]

I started with a 45 and I had this same issue. It did get a bit better as I went up on my pilot. I did read and in fact print out the jetting guide. Also, I'm at 600ft. lol.

Oh.. you are in Texas. No way it could be 6000 feet!

I live at sea level and I find that a 48 pilot would work just fine. I stand corrected.

Can I assume that it runs fine though?

If your main problem is the popping at decel, then there's an air leak somewhere in the exhaust.

Mine pops a little, but not enough to worry about. I live with it.

[crash279]

Oh.. you are in Texas. No way it could be 6000 feet!

I live at sea level and I find that a 48 pilot would work just fine. I stand corrected.

Can I assume that it runs fine though?

If your main problem is the popping at decel, then there's an air leak somewhere in the exhaust.

Mine pops a little, but not enough to worry about. I live with it.

It does run pretty strong, however I do need to pull the plug and see what kinda story it tells. I did read a thread in here about a guy with a similar situation and when he backed down his jetting #'s I think I remember him saying that it helped. If it were a little bit of popping I could probably deal with it, but it is a persistent pop that needs to go away. I just ordered a new exhaust gasket along with some other assorted parts, so I will get that installed as soon as it gets here.

[crash279]

Okay, I have checked the plug and it looks okay from what I can tell. I have been all over the jetting spectrum and nothing is getting rid of the popping. I have raised and lowered the needle, cleaned the airfilter, installed a new exhaust gasket, and still nothing has done anything. The intake and airbox boots both seem to seal well and I do not see any cracking or tears.

Does anybody have any ideas or suggestions? Starting to run out of ideas.

[crash279]

Turned out to be the o-ring on the slide assembly.