KTM help

[MysteriousR1]

I have a 09 KTM 450EXC that I am having trouble getting to idle. Today was the first time I tried to get the bike to run with some success.
I can get it to start, only with the choke on. It will let me take the choke off, but if I do not give it some gas it will die. Will not idle at all.
Also I noticed that if I blip the throttle it will back fire when the rpms come back down.

So far I have only drained the tank, put fresh gas in and drained a bit more. I did see a nice little white chunk come out...
So is this a case of I will have to pull the carb and clean it out good? Seafoam or the like?

Suggestions???

[Kurlon]

Pull carb, clean pilot jet and circuit.

Also, how many hours on it since it's last valve check?

[MysteriousR1]

The bike has about 60hrs on it. I am not to positive, i'd have to dig out my record. 20hrs or so?

How difficult is it to pull the carb and clean it out? I have never done it myself but its time I learn.
I also remember from last year that the jetting needed some fine tuning. This might be a good time to figure that out to

[Chippertheripper]

Cleaning the carb will only cost you a can of cleaner and some time. Seafoam will only cost you a bottle, and a press of the start button. The only problem with seafoam is you just may have to pull the carb afterwards anyways.

[Rambunctous]

Clogged idle jet

[MysteriousR1]

Should the tank have to get removed to get the carb off?

[Tunertype]

Should the tank have to get removed to get the carb off?

I don't know anything exactly bike specific, but usually you need to take the plastics and tank off to get at the shit you need to move to get the carbs off. Just make sure when cleaning to have a clean area. Nothing sucks more than making your carbs more clogged by getting dirt and sand in them when your trying to clean them. Take out the jets and after cleaning make sure you can see light through the holes. If it's really shitty you may need to use wire and pipe cleaners, but usually spraying a ton of carb cleaner will work. Also safety goggles are a good idea, since that carb clean stuff could make you blind and when sprayed in small spots at high pressure it does fly everywhere. You can also dip the carbs by disassemblying them and soaking them. Remove all the delicate rubber parts etc.

also if you can get it to run and idle with choke on or any other method, putting some cleaner in the tank may help if you can run enough of it through the carb. you'll have to waste a tank of gas in your effort and no guarantees. also probably want to do in small runs since you don't want it to over heat just running..

[slowkermit]

It's kind of a bitch but you should be able to sneak the carb out from the side. On my 250xcw, I can just spin the carb body and access the jets through the big drain nut on the bottom of the bowl. Yes I'm lazy.

[MysteriousR1]

Being new to it, i pulled the tank anyways. Now I know I can leave the tank and get to it no problem.

Noticed that the dealership half assed the de-smog process by leaving the vacuum line to the carb. Will be ordering that kit soon.

So, having no clue at all about jetting maybe someone can point me in the right direction. Once I get it all cleaned I would like to get it jetted properly.
When riding the bike in higher rpm's if I am to let off the throttle at all it will pop and back fire. Where do I start...?

Carbs on my kitchen table, perfect time to figure it out!

[R7]

I can't remember if it was my KTM 525 or the YZ 450, but I could rejet or remove the main and pilot jets without doing anything other than removing the big nut on the bottom of the carb?
I have nothing to offer on the rejet, I had the dealer rejet my 525 when it was new and never had an issue with it. Most of the time, popping when letting off the throttle is a combination of 2 things...running lean, and a open/free flowing exhuast. I haven't heard to many 4-strokes that don't pop when letting off the throttle

[Tunertype]

Tuning is generally a trial and error process. THis is why EFI has been great for tuners since it's very easy to change compuer settings, but changing jets is more work. If you get a full jet kit you should get new jets new needles or an adjustable needle and instructions on how to tune. Usually you have Idle, mid and full throttle areas. You increase the full throttle and idle by adjusting the idle jets and idle screws and the main jets. THe mid range is controlled by the needle. On a dyno you make each stage richer until you get no gains then go back one stage.... If your just doing it without a dyno you can use the butt dyno or your own judgement on smoothness etc. Same process applys slowly increase the jetting until no gains are seen and go back one stage once you've increased to the point that it doesn't increase the idle/acceleration. you'll need a kit with multiple jets and needles or an adjustable needle.

[Kurlon]

Before rejetting, get that pilot cleaned up, that may clear your lean issue when you close the throttle.