KTM SXF 450 Bog/Lag

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9/12/2017 9:41 PM

I seem to have a problem with my bike atm, it's a KTM SXF 450 2017 with around 130 hours. (I know that is a lot I just can not justify buying a new bike due to medical school). During my last practise the bike seemed to skip out when I wanted to go full throttle, so whenever I landed after a jump or I tried to set myself up for a jump it bogged for a second then went back to normal. It does the same when standing still if I turn the throttle the full way too fast. Everything engine wise is stock.

Last night I switched two of the three fuel filters hoping it would solve it, no difference while standing still however I have yet to try it on track. Hopefully will do that tonight. A few buddies of mine does have the exact same bike so I will be able to switch parts so I do not end up buying something that is not broken. Before I do that I would like to know what you guys think of it, a lot of people here seem to be great at these things.

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9/13/2017 8:19 AM

Hummm, my first thought would be the small inline fuel filter. Maybe do a compression test?

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9/13/2017 2:17 PM

Tps setting?

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9/13/2017 5:31 PM

Have u checked the valves? I'm assuming it's something new that has just started? Have u checked all the wires and grounds?

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9/13/2017 11:33 PM

CarlinoJoeVideo wrote:

Hummm, my first thought would be the small inline fuel filter. Maybe do a compression test?

I switched all but one fuel filter (there are 3 of them), bike seemed to work fine last night after switching them.. Will have to see this saturday during racing since I only had time to do 2 full laps in race pace.

Mx746: The TPS setting is the same as it was when I first bought it.

ktm-5: I have not checked the valves. I have checked just about every wire that I think could affect it, grounds are fine.

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9/14/2017 12:53 AM
Edited Date/Time: 9/14/2017 12:54 AM

Maybe try a new plug, could the in tank fuel line have a slight kink in it? Idk if that was a problem with the 450s ever had but may be worth a look. Fuel injector getting dirty??

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9/14/2017 3:12 AM

ktm-5 wrote:

Maybe try a new plug, could the in tank fuel line have a slight kink in it? Idk if that was a problem with the 450s ever had but may be worth a look. Fuel injector getting dirty??

Yep most likely will buy a new plug when I go into my dealer later today, the in tank fuel line is fine.

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9/14/2017 3:15 AM

Well hopefully u figure it out, let us know what u find out

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9/14/2017 5:14 AM
Edited Date/Time: 9/14/2017 5:27 AM

Of all the things listed above definitely change the plug that's the simplest. ,swap tanks with your buddy to make sure your fuel pumps not failing then clean the injector. if you still have the problem and the last thing I would check is the TPS if water has got in it they will start to fail you can hook a multimeter up and with the bike running watch the values to see if they're jumping all over. To test its General setting with the multimeter hooked up just tap the start button this will energize the bikes electrical system for 10sec. and you will get a value should be at .64 the lower the number the leaner the bike is. Usually if the TPS is going bad you also have starting issues in the bike will flame out easy. When checking your base value on the TPS you must turn the idle all the way down or you get a false reading.

I'll add this to, this probably won't work for the problem you're having but if you're a KTM owner and the bike starts acting like a carburetor bike with a clogged pilot popping smoking black simply swaping the tank with a bike that runs good will make it run right , don't know why this works but I've done it a few times and it just does.

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9/14/2017 6:28 AM

Clean the fuel injector and the fuel filter on the fuel pump.

Paw Paw

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9/14/2017 6:47 AM
Edited Date/Time: 9/14/2017 6:49 AM

Paw Paw wrote:

Clean the fuel injector and the fuel filter on the fuel pump.

Paw Paw

x2 on this, sounds like dirty injector is letting in to much fuel. A new spark plug would also be good at this time.Their cheap and running rich could start to foul it.

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I don't crash, I just run out of talent

9/14/2017 7:54 AM

CarlinoJoeVideo wrote:

Hummm, my first thought would be the small inline fuel filter. Maybe do a compression test?

Lynch wrote:

I switched all but one fuel filter (there are 3 of them), bike seemed to work fine last night after switching them.. Will have to see this saturday during racing since I only had time to do 2 full laps in race pace.

Mx746: The TPS setting is the same as it was when I first bought it.

ktm-5: I have not checked the valves. I have checked just about every wire that I think could affect it, grounds are fine.

I didn't know there are 3 fuel filters? I only know about the one where the fuel line disconnects.

Where are the others?

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9/14/2017 8:51 AM

CarlinoJoeVideo wrote:

Hummm, my first thought would be the small inline fuel filter. Maybe do a compression test?

Lynch wrote:

I switched all but one fuel filter (there are 3 of them), bike seemed to work fine last night after switching them.. Will have to see this saturday during racing since I only had time to do 2 full laps in race pace.

Mx746: The TPS setting is the same as it was when I first bought it.

ktm-5: I have not checked the valves. I have checked just about every wire that I think could affect it, grounds are fine.

CarlinoJoeVideo wrote:

I didn't know there are 3 fuel filters? I only know about the one where the fuel line disconnects.

Where are the others?

There are two inside the tank on the fuel line, the last one is where the quick release is.

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5/30/2018 3:21 PM

CarlinoJoeVideo wrote:

Hummm, my first thought would be the small inline fuel filter. Maybe do a compression test?

Lynch wrote:

I switched all but one fuel filter (there are 3 of them), bike seemed to work fine last night after switching them.. Will have to see this saturday during racing since I only had time to do 2 full laps in race pace.

Mx746: The TPS setting is the same as it was when I first bought it.

ktm-5: I have not checked the valves. I have checked just about every wire that I think could affect it, grounds are fine.

Did you figure it out?

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5/30/2018 9:34 PM

Hal_Simpson wrote:

Did you figure it out?

Yes! After changing all the fuel filters it worked just fine.

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5/31/2018 5:46 AM

Lynch, 130 hours on the bike last September (!), curious what you're up to now and how everything has been holding up.

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5/31/2018 6:13 AM

MX915 wrote:

Lynch, 130 hours on the bike last September (!), curious what you're up to now and how everything has been holding up.

185 hours atm, bike needed a new rollover sensor two months ago as it broke and made the bike stall whenever. Other than that I have not had any problems. Will pick up a new bike whenever I decide which one to get and I think I will do max 50 hours before changing bikes next time silly Photo

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5/31/2018 6:27 AM

Cool man. That's impressive. Thanks for the feedback.

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