2007 KTM 450 SXF Crackling on throttle both Up and Down.

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anotherguy
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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by anotherguy » Thu Jan 01, 2015 10:26 am

Providing the other systems are in proper order and fuel is good I recommend a JD jetting kit to correct the jetting. I've had one in my '03 CRF450 R since new and it is as close to fuel injection as you can get w/o a fuel pump. Click on the link above for your bike.

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thetable
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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by thetable » Thu Jan 01, 2015 11:20 am

Based on it being a new to you bike, I'm going with: it sat for a while with ethanol fuel in the tank and carb. The ethanol fuel forms a sludge that doesn't come out easily, as in it needs to be physically removed, just chemicals won't cut it. I'd want to get that carb in an ultrasonic cleaner to really make sure everything is clean.

I'd also want to make sure that there aren't any air leaks after the carb; un-metered air can be a real pain to jet for. Spraying a little carb cleaner around the carb and intake manifold will give you an idea of a problem if the idle rises. (Starting fluid works too, but it scares me a little bit.)

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by John L » Thu Jan 01, 2015 1:18 pm

Right on. I will visit that forum. Thanks. I agree, this is the untamed monster version of the KTM 450. I still like it, it has the Rekluse clutch and also the rekluse rear brake/clutch lever thing. The guy that I bought it from was on the way to make it trail friendly and the recluse products helped a lot. I got in it at a very attractive price so I am willing to fiddle with it a little bit. I have it idling fairly smooth after warmed up, so I feel pretty lucky there.

This mornings developments - Compression is at 128psi. I adjusted the fuel mixture screw out a little and it seems to have helped it a little bit but still not quite there. Manual says no more than 2 full turns out so I will stop there.

Carb to jug connection passes the carb spray test. Idle stays true. I just put a new, large capacity tank on it with all new fuel. But how long it sat prior to me I don't have a clue of course. I'd say you are right, like most dirt bikes, this was bought, ran hard a little while and then left in the garage all alone.

I will look into JD Jetting Kit - Thanks!

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by John L » Thu Jan 01, 2015 1:26 pm

Ordered the JD Kit. Thanks again for that link.

I got the thumb turn mixture screw too. Very cool.

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bonehead
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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by bonehead » Thu Jan 01, 2015 1:30 pm

Good news, you can always change the cam if you want but run the baby for a while.

Sometimes people abuse there machines the right before they sell they go thru it, valve clearance, and new plug and yaddah yaddah. Doesn't mean it isn't a good unit just means you have a chance to get it right without much long term damage. Service it sooner then required for a while to help.

JD kits are awesome.
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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by J&J » Thu Jan 01, 2015 1:39 pm

John L wrote: Manual says no more than 2 full turns out so I will stop there.
I think generally that means that it should be in that range.... if it runs better with it open further then that would indicate you need a larger pilot jet. So adjust idle screw to where it idles best when warmed up then see where it's at. Will be different this time of year than summer.

JD has good stuff & good tuning tips :thumbup:

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by John L » Thu Jan 01, 2015 2:26 pm

...good tips here too. continued thanks to all you folks for the help.

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by restukey » Thu Jan 01, 2015 4:25 pm

John L wrote: Its still not running just right though. It does not backfire, but when I roll on the throtle it is making a crackling type of noise. Kinda like hundreds of small, mild backfire sounds.
That doesn't sound like a jetting issue to me? I would check the cam timing. Stuff that can go wrong on the carb: air jets don't line up at the airboot, ap diaphram is cracked, throttle slide installed backwards, throttle slide diaphram needs replacement. It sounds like an air leak or cam timing, my wild guess.

Edit: But it would be good to know what the jetting is? With the cold weather its going to be lean right now on the main.

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by John L » Fri Jan 02, 2015 2:05 pm

Just a follow up... I also got the factory exhaust with the bike. I removed the FMF and stuck it on as an experiment and it is running LOTS better now as a result. I couldn't believe what a difference. I took it for a local whip in the cold on the many back roads here, really nice... it's a different bike altogether now.

Still haven't addressed jetting for the cold (or any other temp) but I will as soon as the JD kit arrives here.

With the factory exhaust I notice that it is no louder or quieter than the FMF.. it sounds the very much same, but boy does it run better - no crackling noise.

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Re: 2007 KTM 450 SXF Crackling on throttle both Up and Down.

Post by bonehead » Fri Jan 02, 2015 2:24 pm

John L wrote:Just a follow up... I also got the factory exhaust with the bike. I removed the FMF and stuck it on as an experiment and it is running LOTS better now as a result. I couldn't believe what a difference. I took it for a local whip in the cold on the many back roads here, really nice... it's a different bike altogether now.

Still haven't addressed jetting for the cold (or any other temp) but I will as soon as the JD kit arrives here.

With the factory exhaust I notice that it is no louder or quieter than the FMF.. it sounds the very much same, but boy does it run better - no crackling noise.
Don't rejet with the factory exhaust. Put the FMF back on when jetting then you will really be surprised.
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