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Hanging Idle for the 2nd time

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Hello fellow thumpers!

 

I have a 2009 450 XC-W.  Love the bike, haven't had any major problems since purchasing the bike used with around 35 hours.  No smoking, no oil transfer - just some great trail riding and hill climbing fun!  I keep my bike extremely well maintained.  I change the engine oil every 5 hours and trans oil every 10.  I clean the air filter every 5 hours too.  I really don't want to have to do a rebuild for a long time. 

 

When I first got the bike, I was experiencing the notorious hanging idle.  I asked a knowlegeable guy at the local KTM dealer and he said to drain the fuel off from the carb every ride and to use StarTron fuel additive with every tank of fuel.  Suprisingly, this worked!

 

This past winter, I installed a JD jet kit, checked the valves - they were spot on, changed spark plug, did the oil pump mod, and went over the rest of the bike.  I've ridden nearly 20 hours since then with regular maintenance.

 

Last weekend, I went on a long trip and put around 80 hard miles on the bike.  Near the end of the trip, I started getting that annoying hanging idle again. I figured it was probably because I had been in alot of dust and the air filter was dirty.  I did NOT get any excessive mud or water up into the air box though. After getting home, cleaning the bike, cleaning the air filter, and draining off the carb, I still have the hanging idle.  I tried fussing with the fuel screw but it made to difference so I put it back where it was.

 

Can anyone shed any light on this?  Could I have possibly gotten some dirt in the carb?  Should I start by a good carb cleaning?  I really don't think its jetting related because the bike was running superb and the temp hasn't changed significantly, nor has my elevation.  It has gotten to be a bit more humid though.  Maybe my valves are due?  To my knowledge, they have never been adjusted.  Like I said, I did check them somewhere around 20 hours ago and they were spot on. Not sure if this could a factor?  It starts very easily still. 

 

Basically I've tried all the easy stuff that I know of, and don't want to dive into teardown mode until I have a bit better of direction.

 

Any ideas??  Thanks guys!

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If the fuel screw made no difference then your pilot jet is likely partially plugged up. Maybe a piece of junk got there during the ride. Shoot some carb cleaner and compressed air through the pilot circuit and see if that makes a difference. Adjusting the fuel screw should definitely affect how it runs.

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cables are a major cause of this too. I remove all my close cables and make sure the slide is slmming closed. I leave the close cable in place in the throttle tube and leave it disconnected in place ny the carb. This way I can have an emergency cable if the open cable breaks. Remove the tank, check the cable routing to be sure its free and not the cable. It could also be in the twist tube with dirt or cable fray.

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Thanks for the replies!!

My gut feeling is that its my pilot. I probably got a bad batch of fuel or something slipped past my air filter or fuel filter. Im going to clean the pilot today and see what happens.

I will also check my cables, its never a bad idea anyways.

I hate having to fuss with the Carb on these bikes... Its not incredibly difficult but it's just tight. My buddy has a 300xc and im always jealous seeing how easily he can clean and make jetting adjustments to his Carb.

Ill post my findings once im done.

Thanks again guys!

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You should be able to loosen the intake clamps, rotate the carb to get to the pilot and main jets.

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I've found the problem.

 

I loosened the clamps and turned the carb to remove the 17mm cap at the bottom.  I cleaned the pilot out and the main jet out.  Everything looked normal.  After re-installing the jets and the cap, I noticed that the intake boot on the engine side of the carb was torn.....

 

I ended up having to pull the carb off anyway to get to that boot.  Its on order from my local KTM store.  Luckily, I don't like riding through mud or water.  It could have been catastrophic.

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