WR 450 08 Jetting problem - high rmp when is cold

Hi guys. I have just rejet my bike because it was too rich.

Now it runs better, smoothier, no backfire.

But when is cold and start it has realy high rpm at idle. I adjust the idle speed and ride it for 15-20min and when the bike gets hot and close the throttle it shuts down. Start it again with hot start (difficult to start) and the bike stays with low rmp at idle and shut down again. then I adjust the idle speed again but the rpm are not steady. when i give some throttle increase and drop down again.

My bike is a WR450 2008.

Before i was using the jets from the GYTR-AIS kit

Main jet: 175 (GYTR-AIS)

Main Air Jet: 110 (GYTR-AIS)

Pilot Jet: 50 (GYTR-AIS)

PAJ: 80 (stock)

Leak Jet: ? from GYTR-AIS

Starter Jet: 65 (stock)

Fuel screw: stock

Needle Model/Clip position: GYTR AIS 4th

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): OFF

AIS Removed (Y/N): Y

Airfilter Brand: Notoil sm

Exhaust Brand: FMF Factory 4.1 complete, powerbomb

Average Altitude: 0-1000ft

Average Temp: 60-90

Now i replace the

Main jet: 170 JD

pilot jet: 48 JD

Jet Needle: JD red - 4th

and put a ZIP TY Fuel Screw 1/2 turn (still try to adjust it). :thumbsup:

Now is summer here, about 90f.

Need to go to a smaller pilot-jet?

Or is something else?

something is funny

i put the JD jetting kit in with the jets JD supplied... 168 main. red needle in the stock position.. but i am thinking of moving the clip down/needle up!

and my bike is a little hard to start fully hot... ie 3-5 cranks with the starter.

but runs amazing any RPM... 2008 WR 450 F , stock exhaust with after market end cap...

780 Ft above sea level where i ride.

The problem solved by it'self!!! just riding around 1-2 times and the bike runs perfect now. probably was the sudden jump to 170MJ and 48 PJ.


JD is a perfect kit!

i had this problem with a 2004 cr125..when you would pull the clutch in it would bring the rpms up some? it was like in the middle of winter though so it was a tad lean on the bottom end.....i got rid of that turd awhile ago though haha

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