2005 WR450, new bike to me, have some issues/problems

Hey guys,

I am normally in the DRZ boards. I have a supermoto which I've played with the carb a little bit (rejetting) and I am familiar with that. I asked what jets/needle to use and it worked perfect for where we live (sea level-1000ft). I have no issues with that bike.

I ended up getting a used WRF450 (2005). It already had some stuff done to it, but thank god I got everything that went with it. It has the AIS removed (and plugged off at the motor), has the gray wire mod (checked that last night), has the air box holes plugged up. Also the exhaust has been gutted as far as I can see, and a fatter tail pipe put on. It also has a JD jetting kit (I don't know which jets are in there, I DO know that the red needle is in there though). I am unaware of what clip it's at. It also has a red fuel screw with numbering on it. So I know that's not stock.

It has a nasty surge at time, like it wants to just take off and rev's up. It hunts for idle just sitting, even after warming up. It's pretty warm as far as the exhaust feel. I am comparing to my DRZ, but it's HOT. The head pipe does glow if letting it sit which I read is a normal trait of the bike. I need to check the jetting to make sure it's right. I'll be mostly riding the bike 1000ft-4000ft at most.

So my question is..........what jetting/needle should I be using for the elevation I'll be riding mostly? Also, I did read a tech section on checking/changing the jets. With the carb on the bike do I have to disconnect the throttle cables or can they stay and just rotate everything? They don't look so easy to disconnect.

I want to get the jetting figured out, then if the idle/surging is still there go from there. If I take it around the block it seems to run fine but at slow going up a driveway speed it surges and wants to lurch, so there's no slow speed anything. I have to keep my hand over and on the brakes to get it go do a tight turn.

Right now I have the tank off (ripped a fuel line) so I'll get a replacement for that, but wanting to know about the carb & jetting. I have a kit full of jets (whatever was left from the JD kit) and the blue needle as well as the stock needle. My DRZ I used the blue, so I am thrown off by the red that would be in the engine.

Any help would be greatly appreciated.

have you found any good info yet I have an 05' WR450 and have had a hell of a time getting it to run good. once I figured it out it has ran like a bat outta hell if you need any suggestions still, let me know

Sounds to me like you have things jetted a little lean. Also --- the changes in idle RPM could also indicate the same thing.

I'd start by adjusting the fuel screw w/ the numbers on it. (normally the idle screw is recessed....the red numbered knob is just a tool to make it easier to adjust..... I still have to use a small screw driver to adjust mine)

You simply turn it one way until --- a) it either starts to bog down :busted: the idle increases....... while blipping the throttle. While doing this keep adjusting the idle back to normal......

Eventually you should find a sweet spot that gives you crisp throttle response without much bog --- and without much backfire popping. If you can't find this spot --- your idle jet just needs to be changed out.

It has a nasty surge at time, like it wants to just take off and rev's up. It hunts for idle just sitting, even after warming up

I have always been told these symptoms meant an air leak at the carb boot on carburated machines. Usually the air leak is AFTER the air filter, but BEFORE the carburater. Just a thought :busted:

Usually the air leak is AFTER the air filter, but BEFORE the carburater.

What is the difference if its before or after the filter? :busted: I just dont see how your analogy is logical

If you haven't done so, clean the carb....never know how long that bad gas has sat in there. Then, while you're in there, check the jets so you know where you are starting from, and where you are from stock. What altitudes/temps you riding in? It matters....

With the exhaust de-restriction and AIS removed (and gray wire unplugged), you have leaned out the mixture already (has the airbox restrictor been taken off, from the top?)....if it hasn't been jetted to compensate, you will be lean, as is illustrated by your "searching" idle.

Wasn't the red needle from JD the high altitude one? If you're down low altitudes (sub 5k?) then you're lean with this needle as well.

Do your homework with finding what jets are in there, and we'll go from there once you've verified a clean carb to start with.

I did this to my "new to me" 05 WR450 and she runs like a scalded dog....reminds me of my YZ450 I had a couple years back....tons of fun!!

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