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When I start my 2008 KTM XF-C 450 with the choke on it starts right up and idles perfectly. However, after I push the choke in and let it idle it likes to stall out after maybe 10-15 seconds. Other than that I have no problems restarting or anything what so ever even when it's cold or hot. I started mixing Lucas oil octane in my fuel to boost it a little bit could that be the problem? I tried adjusting my idle knob on the carb but didn't want to mess anything up. Do I loosen this knob more to allow more gas inside? Any other ideas on why it like to stall after I push in the choke? Does this beast need to warm up for a while with the choke on before I push in the choke? Let me know!

thanks guys 

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That model is pretty cold blooded. Does it run great once warm? It might be better with some fuel screw adjustment, which is that other knob sticking straight down. Get it warm, once the idle is stabilised, adjust that screw for the highest idle, then adjust the normal idle screw to bring the idle speed back to normal. Sometimes the changes of the season require messing with the carb to keep it running good.

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I'm going to try draining the gas that's in there adjust the carb knobs and start over with fresh gas then see what happens.  I'd like to not pull off the carb and do that (I've never done it before) but I'm sure one day I'll have to I just hope that day is not within the next couple upcoming races.

I use Lucas Oil Octane boost but I'm going to stop using that and just run premium 91 gas instead.  I've heard that the booster can leave a thin film on the jets and clog them up over time?  What kind of gas do you recommend for the KTM 450's?

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I'm going to try draining the gas that's in there adjust the carb knobs and start over with fresh gas then see what happens.  I'd like to not pull off the carb and do that (I've never done it before) but I'm sure one day I'll have to I just hope that day is not within the next couple upcoming races.
I use Lucas Oil Octane boost but I'm going to stop using that and just run premium 91 gas instead.  I've heard that the booster can leave a thin film on the jets and clog them up over time?  What kind of gas do you recommend for the KTM 450's?

If you can avoid fuel with ethanol (E10 or E15) that's a good start, but any pump fuel is going to start to clog up the works if it sits for more that a 4, 5 weeks. Drain the carb if it's gonna sit. Don't be afraid to pull the carb, can usually loosen and twist carb to get the bowl off, get some slack in cables, loosen boots and twist! Buy a set of welding tip cleaners to get the jets clean. Or just buy new jets. Watch some YouTube vids. Pilot jets are notorious for clogging because they are so small. Watch a vid on setting fuel screw also. I always got an extended one so I could reach it.

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