2016 KTM250SXF Cranking Issues

Industry Moto
Edited Date/Time 4/5/2022 8:59am
So this poor bike has been at 2 dealerships and now at my shop and I would really like to be the one to fix it. The issue is it will barely turn over if the throttle is cracked. The first dealership said it was the battery so he upgraded to the bigger 17 batt. But that did nothing, second dealership said it was the starter so he replaced it. that also was a bust. Even if the Idle is set or the enrichener is activated It labors really bad. If I back off the Idle and enrichener it turns over fast and easy. I ruled out all the electronics by jumping right to the starter. Ive tried multiple batteries, Even an optima car batt. Ive tried 3 starters,(all OEM) and different cams and nothing has changed at all. There is signs that the bottom end has been apart so I have pulled the motor. Before tear down I again Jumped the starter with the motor on the bench same result. Pulled the top end everything looks perfect, I went ahead and split the cases just looking for anything out of the ordinary and it all looks great. (bike only has 34HRS and that was confirmed by a dealer) Also was hooked up to KTM XC2 computer no codes. Its acting like it has too much compression. Compression is 206psi. Now before the argument starts as it has on other forums Its NOT the comp release these bike do NOT have compression releases.
Heres where it gets even weirder. my customer stated he would bump start the bike go riding saying the bike runs great so I replicated this and hes right. It idles great and the engine revs all the way to the limiter. After hours and hours of searching the internet I found one other post about the same issue but it was never solved! Ive been doing this for over 30 Years and Im stumped. So let me have your best guesses and Thanks. lol
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Thisusernameisavailable 12/18/2019 4:03pm
12/18/2019 4:03pm
Strange one.
I’d be looking towards the injector. Checking the voltage and swapping out the unit.
If the injector is faulty and spraying in too much fuel at such low RPM, that would in effect increase compression by virtue of liquid being impossible to compress, like air would.

Thinking out loud, when you bump start it you’re turning the bike over faster and so it will start. Once it’s started the ‘extra’ fuel isn’t an issue as it’s at a higher RPM.

Just a punt.. but as you say you’ve already looked in to the more obvious.
Industry Moto 12/18/2019 4:08pm
12/18/2019 4:08pm
Thisusernameisavailable wrote:
Strange one. I’d be looking towards the injector. Checking the voltage and swapping out the unit. If the injector is faulty and spraying in too much...
Strange one.
I’d be looking towards the injector. Checking the voltage and swapping out the unit.
If the injector is faulty and spraying in too much fuel at such low RPM, that would in effect increase compression by virtue of liquid being impossible to compress, like air would.

Thinking out loud, when you bump start it you’re turning the bike over faster and so it will start. Once it’s started the ‘extra’ fuel isn’t an issue as it’s at a higher RPM.

Just a punt.. but as you say you’ve already looked in to the more obvious.
In my post I stated that I jumped directly to the starter with the engine on my bench. No throttle body. That would rule out all electrical. Seems to be a compression issue.
Thisusernameisavailable 12/18/2019 4:14pm
12/18/2019 4:14pm
Thisusernameisavailable wrote:
Strange one. I’d be looking towards the injector. Checking the voltage and swapping out the unit. If the injector is faulty and spraying in too much...
Strange one.
I’d be looking towards the injector. Checking the voltage and swapping out the unit.
If the injector is faulty and spraying in too much fuel at such low RPM, that would in effect increase compression by virtue of liquid being impossible to compress, like air would.

Thinking out loud, when you bump start it you’re turning the bike over faster and so it will start. Once it’s started the ‘extra’ fuel isn’t an issue as it’s at a higher RPM.

Just a punt.. but as you say you’ve already looked in to the more obvious.
Industry Moto wrote:
In my post I stated that I jumped directly to the starter with the engine on my bench. No throttle body. That would rule out all...
In my post I stated that I jumped directly to the starter with the engine on my bench. No throttle body. That would rule out all electrical. Seems to be a compression issue.
So with the engine on your bench, with no throttle body fitted, that would simulate ‘throttle wide open’?
Maximum air, no fuel- and the motor turns over slowly/laboured?

With the motor on your bench, no throttle body fitted, If you ‘plug’ the intake with your hand or similar, then the cranking speed increases?
Industry Moto 12/18/2019 4:50pm
12/18/2019 4:50pm
Thisusernameisavailable wrote:
Strange one. I’d be looking towards the injector. Checking the voltage and swapping out the unit. If the injector is faulty and spraying in too much...
Strange one.
I’d be looking towards the injector. Checking the voltage and swapping out the unit.
If the injector is faulty and spraying in too much fuel at such low RPM, that would in effect increase compression by virtue of liquid being impossible to compress, like air would.

Thinking out loud, when you bump start it you’re turning the bike over faster and so it will start. Once it’s started the ‘extra’ fuel isn’t an issue as it’s at a higher RPM.

Just a punt.. but as you say you’ve already looked in to the more obvious.
Industry Moto wrote:
In my post I stated that I jumped directly to the starter with the engine on my bench. No throttle body. That would rule out all...
In my post I stated that I jumped directly to the starter with the engine on my bench. No throttle body. That would rule out all electrical. Seems to be a compression issue.
Thisusernameisavailable wrote:
So with the engine on your bench, with no throttle body fitted, that would simulate ‘throttle wide open’? Maximum air, no fuel- and the motor turns...
So with the engine on your bench, with no throttle body fitted, that would simulate ‘throttle wide open’?
Maximum air, no fuel- and the motor turns over slowly/laboured?

With the motor on your bench, no throttle body fitted, If you ‘plug’ the intake with your hand or similar, then the cranking speed increases?
With the motor on your bench, no throttle body fitted, If you ‘plug’ the intake with your hand or similar, then the cranking speed increases? YES thats correct

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Jg144
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Jg144 12/18/2019 6:46pm
12/18/2019 6:46pm
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy a new one or try one out of another unit if you have access to one.
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Mossy
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Mossy 12/18/2019 7:03pm
12/18/2019 7:03pm
Sell that junk bike and buy a new Suzuki
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inthebadboycorner 12/18/2019 9:46pm
12/18/2019 9:46pm
Jg144 wrote:
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy...
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy a new one or try one out of another unit if you have access to one.
Is this a type of clutch in the starter, if so would it not crank sounding fast? But actually crank slow?
Industry Moto 12/18/2019 10:29pm
12/18/2019 10:29pm
Jg144 wrote:
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy...
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy a new one or try one out of another unit if you have access to one.
What does the tourque limiter have to do with the starter speed in relation to the air intake? This has been suggested a couple of times but only because the guys did not read the whole post. With the idle backed off and the butterfly completely shut so almost no air is getting to the engine it turns over completly normal. If the butterfly is cracked even a little it barely turns over.
Industry Moto 12/18/2019 10:30pm
12/18/2019 10:30pm
Mossy wrote:
Sell that junk bike and buy a new Suzuki
I myself own hondas. Suzukis are way to slow. lol
4
silver753
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silver753 12/18/2019 10:34pm
12/18/2019 10:34pm
Part number is 79239005044, it's part of the flywheel. Some people call it the starter clutch also. Just like Jg144 says, it could be your problem.

If you have access to the KTM diag tool, or know of a dealer that does, they should be able to contact KTM and they can walk you through the issue and give you multiple things to try. If the dealer doesn't, I hate to say it but they are just being lazy and giving up. Although it does sound like a pretty odd issue, I'll do some thinking and let you know if I think of anything.
Industry Moto 12/18/2019 10:35pm
12/18/2019 10:35pm
Jg144 wrote:
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy...
The torque limiter is slipping causing it to turnover too slow to start. There isn’t a way to check it so you will have to buy a new one or try one out of another unit if you have access to one.
inthebadboycorner wrote:
Is this a type of clutch in the starter, if so would it not crank sounding fast? But actually crank slow?
IT has a starter clutch and a torque limiter. Usually when they go out the starter just freewheels and the motor does not turn over. The torque limiter is for backfires or kick backs, it limits the force going back to the starter. And everything Ive read about them failing says they freewheel also.
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silver753
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silver753 12/18/2019 10:41pm
12/18/2019 10:41pm
Try 2 things if you can, do a fuel pump pressure test. Going off of memory, you should have roughly 46 to 52psi. And it will shoot across the room at 20psi, but it will have erratic starting issues if it falls out of the 46 to 52psi range. Not sure if this would be the issue, but something to eliminate.

Next I would reset the TPS sensor, again, not sure this is the issue but just something to check.

Another thing the 250 SX-F's have an issue with is ripped spark plug caps. Pretty ridiculous sounding, but if they get a slight tear it will ground out against the head and cause all sorts of starting issues. Again, just eliminating a few things that are common.
cody41
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cody41 12/19/2019 3:57am
12/19/2019 3:57am
Part it out. I had a 16 450sxf and it was by far the most problematic bike I’ve ever owned.
CHRIS58
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CHRIS58 12/19/2019 10:35am
12/19/2019 10:35am
Industry Moto wrote:
So this poor bike has been at 2 dealerships and now at my shop and I would really like to be the one to fix it...
So this poor bike has been at 2 dealerships and now at my shop and I would really like to be the one to fix it. The issue is it will barely turn over if the throttle is cracked. The first dealership said it was the battery so he upgraded to the bigger 17 batt. But that did nothing, second dealership said it was the starter so he replaced it. that also was a bust. Even if the Idle is set or the enrichener is activated It labors really bad. If I back off the Idle and enrichener it turns over fast and easy. I ruled out all the electronics by jumping right to the starter. Ive tried multiple batteries, Even an optima car batt. Ive tried 3 starters,(all OEM) and different cams and nothing has changed at all. There is signs that the bottom end has been apart so I have pulled the motor. Before tear down I again Jumped the starter with the motor on the bench same result. Pulled the top end everything looks perfect, I went ahead and split the cases just looking for anything out of the ordinary and it all looks great. (bike only has 34HRS and that was confirmed by a dealer) Also was hooked up to KTM XC2 computer no codes. Its acting like it has too much compression. Compression is 206psi. Now before the argument starts as it has on other forums Its NOT the comp release these bike do NOT have compression releases.
Heres where it gets even weirder. my customer stated he would bump start the bike go riding saying the bike runs great so I replicated this and hes right. It idles great and the engine revs all the way to the limiter. After hours and hours of searching the internet I found one other post about the same issue but it was never solved! Ive been doing this for over 30 Years and Im stumped. So let me have your best guesses and Thanks. lol
Free wheel starter gear
1
Industry Moto 12/19/2019 11:08am
12/19/2019 11:08am
silver753 wrote:
Try 2 things if you can, do a fuel pump pressure test. Going off of memory, you should have roughly 46 to 52psi. And it will...
Try 2 things if you can, do a fuel pump pressure test. Going off of memory, you should have roughly 46 to 52psi. And it will shoot across the room at 20psi, but it will have erratic starting issues if it falls out of the 46 to 52psi range. Not sure if this would be the issue, but something to eliminate.

Next I would reset the TPS sensor, again, not sure this is the issue but just something to check.

Another thing the 250 SX-F's have an issue with is ripped spark plug caps. Pretty ridiculous sounding, but if they get a slight tear it will ground out against the head and cause all sorts of starting issues. Again, just eliminating a few things that are common.
Hey thanks for the reply., But you must not have read my post, lol most people dont. I bypassed all eletrical, And Jumped the starter directly with the motor on my bench. No throttlbody, no tps. The bike runs flawless if bump started.Its building too much compression. with the throttle closed it turns over really fast, as soon as the butterfly is cracked even a little bit, or pull the cold start it puts a load on the motor.
Industry Moto 12/19/2019 11:14am
12/19/2019 11:14am
silver753 wrote:
Part number is 79239005044, it's part of the flywheel. Some people call it the starter clutch also. Just like Jg144 says, it could be your problem...
Part number is 79239005044, it's part of the flywheel. Some people call it the starter clutch also. Just like Jg144 says, it could be your problem.

If you have access to the KTM diag tool, or know of a dealer that does, they should be able to contact KTM and they can walk you through the issue and give you multiple things to try. If the dealer doesn't, I hate to say it but they are just being lazy and giving up. Although it does sound like a pretty odd issue, I'll do some thinking and let you know if I think of anything.
Its already been at 2 KTM dealers both ran Diag on KTM XC-2, There's no codes. Ive bypassed all electrical and sensors. I have the motor on my bench with no throttle body jump directly to the starter if the intake is plugged simulating a closed throttle it turns over fast as soon as air is introduced the motor will barely turn over. the starter clutch was replaced a while ago but it is definitely not slipping. seems to be building too much compression.
Jg144
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Jg144 12/19/2019 6:27pm
12/19/2019 6:27pm
I’ve dealt with this issue at work on the same year of 250 sxf. I didn’t think it was the issue either when I was talking with the guys at Ktm. The bike turns over too slow to start. When I replaced it it was immediately noticeable and the bike fired instantly.
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Jg144
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Jg144 12/19/2019 6:31pm
12/19/2019 6:31pm
Plugging into the xc2 won’t tell you anything because it’s not a sensor issue. This was the last suggestion that Ktm had for me too try and it was the problem.
2
Industry Moto 12/19/2019 8:41pm
12/19/2019 8:41pm
Jg144 wrote:
Plugging into the xc2 won’t tell you anything because it’s not a sensor issue. This was the last suggestion that Ktm had for me too try...
Plugging into the xc2 won’t tell you anything because it’s not a sensor issue. This was the last suggestion that Ktm had for me too try and it was the problem.
]Finally got a Video up.
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BT747
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BT747 12/20/2019 8:02am
12/20/2019 8:02am
Put the motor back in the bike with everything connected like it should and troubleshoot from there. Check all grounds, connections, check all voltages. Sounds like the bike has had a lot of tools on it and it would be hard for someone to diagnose over the net. Easiest would be find another bike to swap parts, an advantage a dealer has. If the crank spins freely and timing is on then probably electrical
slowgti
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slowgti 12/20/2019 8:59am
12/20/2019 8:59am
Put a tach on the flywheel and see what the cranking rpm is with the intake open and closed.
Rick Amatuzio 12/20/2019 9:08am
12/20/2019 9:08am
Industry Moto wrote:
So this poor bike has been at 2 dealerships and now at my shop and I would really like to be the one to fix it...
So this poor bike has been at 2 dealerships and now at my shop and I would really like to be the one to fix it. The issue is it will barely turn over if the throttle is cracked. The first dealership said it was the battery so he upgraded to the bigger 17 batt. But that did nothing, second dealership said it was the starter so he replaced it. that also was a bust. Even if the Idle is set or the enrichener is activated It labors really bad. If I back off the Idle and enrichener it turns over fast and easy. I ruled out all the electronics by jumping right to the starter. Ive tried multiple batteries, Even an optima car batt. Ive tried 3 starters,(all OEM) and different cams and nothing has changed at all. There is signs that the bottom end has been apart so I have pulled the motor. Before tear down I again Jumped the starter with the motor on the bench same result. Pulled the top end everything looks perfect, I went ahead and split the cases just looking for anything out of the ordinary and it all looks great. (bike only has 34HRS and that was confirmed by a dealer) Also was hooked up to KTM XC2 computer no codes. Its acting like it has too much compression. Compression is 206psi. Now before the argument starts as it has on other forums Its NOT the comp release these bike do NOT have compression releases.
Heres where it gets even weirder. my customer stated he would bump start the bike go riding saying the bike runs great so I replicated this and hes right. It idles great and the engine revs all the way to the limiter. After hours and hours of searching the internet I found one other post about the same issue but it was never solved! Ive been doing this for over 30 Years and Im stumped. So let me have your best guesses and Thanks. lol
Sounds like your cam timing is advanced. That will build more cylinder pressure at cranking. The only other thing that causes that would be advanced ignition timing, but since you had the TB off that will eliminate that.

I had a Pontiac 455 and the timing gear was offset 12 degrees from the factory (happens more than you think) and the motor had 260psi cranking compression. After retarding the cam timing to straight up it was 180psi.

Industry Moto 12/20/2019 11:48am
12/20/2019 11:48am
BT747 wrote:
Put the motor back in the bike with everything connected like it should and troubleshoot from there. Check all grounds, connections, check all voltages. Sounds like...
Put the motor back in the bike with everything connected like it should and troubleshoot from there. Check all grounds, connections, check all voltages. Sounds like the bike has had a lot of tools on it and it would be hard for someone to diagnose over the net. Easiest would be find another bike to swap parts, an advantage a dealer has. If the crank spins freely and timing is on then probably electrical
Hey BT747 the reason the engine is on the bench is because of all the troubleshooting. With everything disconnected and jumping the starter directly it does the same thing. So with the engine on the bench and jumping the starter again same symptoms. So that rules out electrical, throttlebody, TPS, ect, ect. Its in the engine. Getting a call from a KTM Factory Tech today
Jg144
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Jg144 12/20/2019 8:03pm
12/20/2019 8:03pm
Industry moto I am a tech at a Ktm dealer. I was in the same boat as you tried a fuel pump, injector, battery valve inspection, leak down, compression check bunch of time with the xc2 a few calls to Ktm tech line and it was the torque limiter. The bike was almost impossible to get started. I had to crack the throttle the perfect amount to get it to fire up and once running it was totally fine you would never know it had an issue until you shit if off and tried to restart. I know it sounds crazy but it fixed it. I didn’t realize how much slower it turned over until I replaced the torque limiter. I’m surprised to see another unit with the same exact symptoms. Anyway good luck with it hope you get it fixed.
1
Rick Amatuzio 12/20/2019 8:28pm
12/20/2019 8:28pm
Jg144 wrote:
Industry moto I am a tech at a Ktm dealer. I was in the same boat as you tried a fuel pump, injector, battery valve inspection...
Industry moto I am a tech at a Ktm dealer. I was in the same boat as you tried a fuel pump, injector, battery valve inspection, leak down, compression check bunch of time with the xc2 a few calls to Ktm tech line and it was the torque limiter. The bike was almost impossible to get started. I had to crack the throttle the perfect amount to get it to fire up and once running it was totally fine you would never know it had an issue until you shit if off and tried to restart. I know it sounds crazy but it fixed it. I didn’t realize how much slower it turned over until I replaced the torque limiter. I’m surprised to see another unit with the same exact symptoms. Anyway good luck with it hope you get it fixed.
Torque limiter as in bendix, and its slipping? He said he replaced the starter and that sprague makes a lot of noise if it’s slipping. Cam timing will make it nearly impossible to crank over if it’s a tooth off, or the gear slips (is KTM presser on like Honda?) as the exhaust valve shuts too early. I’m curious and hope he posts the solution, this is interesting
Jg144
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Jg144 12/20/2019 10:13pm
12/20/2019 10:13pm
No not the starter clutch the torque limiter it’s in between the starter and starter clutch.
Underground 12/20/2019 10:32pm
12/20/2019 10:32pm
Jg144 wrote:
[img]https://p.vitalmx.com/photos/forums/2019/12/20/393050/s1200_2017D25A_6BAC_4F7A_A571_C25450A9D8F0.jpg[/img]

Yep that;'s it. 08-10 had the same issue after a few years. Worth changing when you do a full rebuild. Just keep throwing money at it Wink

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