Hey all, new to Vital MX & new to the 4-Stroke game. I just bought a 2018 KTM 250 SX-F, and when I try to start it, it just cranks, and cranks, and cranks, but no start. If I hook it up to a jump box, it starts right away.
9/10 if I apply any throttle, or go to blip the throttle after starting, the bike just dies. I got the bike to run & idle for about 3 minutes and then I went to hop on, put it in gear, went to blip the throttle & the bike just died. I started it again with the jump box, this time SLOWLYYYYY rolled onto the throttle and got it rolling. I went down the street & the bike felt like it maybe had 30% of its power. Stopped at the end of the street to turn around, went to blip throttle again to roll off clutch & bike died again.
The bike won’t start with the electric start if it’s not hooked up to a jump box. But I don’t see how that could be affecting the bike dying when throttle is applied & the bike only having 30% of its power.
Any help & tips are appreciated. Thanks!
-SK295
first off you might need a new battery. these ktm's crank pretty slow with the stock one. in the future when you start it just hit the start button once and let go and wait a few seconds. this warms up the battery and also primes the fuel pump.
as far as it not running right and easy thing to try is resetting your tps parameters. how you do that is press and hold both the killswitch and start button at the same time for about 3 seconds, let go and wait a few seconds, (you will hear a "click" sound) then do the same thing with the throttle all the way open.
another easy thing is to check the inline fuel filter. it's a little white cone shaped filter right where you disconnect the fuel line. they get clogged from time to time.
+1 on the battery. Either needs a tender or new battery.
Inline fuel filter also is a good check. Then check the injector. Then fuel pump. Bike isnt getting fuel it seems.
Inline fuel filter is my bet.
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Definitely! That totally would make sense. I’m gonna go to the dealership today to get a battery & fuel filter, after I put the new battery in I’ll reset the TPS.
Thanks for the help, I’ll keep y’all updated with how it turns out!
- SK295
It could also be the in tank filter.
I had the same thing on a KTM SXF 250 and it really was a small fuel filter
Just put the new battery in & the bike doesn’t start unless I give it a bit of gas while on the starter. I also changed the inline fuel filter & reset TPS parameters.
If I crack the throttle, the bike still just dies, but if I roll onto it or hold the throttle a little bit from when I start it to keeping it like that on idle then slip off clutch and it’ll go, but I can’t just crack the throttle going slow or from idle otherwise the bike just dies. At higher RPM if I crack it & pin it, it doesn’t die, only at idle & low RPM’s it’ll die when I blip the throttle.
Also the bike sorta feels like 50% power now, instead of 30%.
Faulty or failing fuel pump, dirty injector or in tank fuel filter are the next logical areas to look into.
next thing to try would be the fuel filter inside the tank. Might as well check the valve clearances since its free, but i still would think it to be a fuel issue. small chance but maybe your gas cap isn't breathing properly?
I do have a very SLIGHT valve cover gasket leak, but I don’t see that causing an issue with valve clearances. I’m completely new to 4 strokes, especially these new ones so I honestly have no clue how to work on them. I probably couldn’t even do a top end on one. I’m gonna try the in tank fuel filter next, then injector if that doesn’t fix it.
If putting a new in tank fuel filter or injector doesn’t work, I’ll try fuel pump next or just take it into the dealership to get diagnosed & fixed because I really don’t want to just be throwing money & parts at this thing lol. The battery alone was just $200 😂 gotta pay to play I guess.
I’ll definitely keep you all updated. What’s the best way to check valve clearances at home for a beginner? Or would I just be better off having the dealership do that?
Gotcha, should I go for pump or injector first?
Figured one out yesterday Take the map sensor apart and change the o ring inside
Where’s the map sensor on this bike? Sorry I’m new to the whole 4 stroke thing, especially the fuel injected ones.
on the top of throttle body
I would check the idle speed. These 4 strokes have to idle really high or they will flame out.
My experience with this KTM issue was a dirty injector, I did clean it but ultimately replaced it, problem solved.
I also agree these things like to idle really high.
This is going to sound really stupid, but change the spark plug.
While you are replacing the cam cover o-ring, check the valve clearances just to see. It’s probably not your main issue but it can be contributing to the problem.
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