KTM 250 Sxf Slow Crank

Dampvan
Posts
5
Joined
2/4/2025
Location
Inver, GB

Having  problem with slow crank 

So Far

Replaced battery 3 times and also installed battery out of a larger bike. Still slow crank 12.7 v at starter

Remade all earths

Bypassed starter relay still slow crank and stops if you crank open throttle.

Back off idle screw engine cranks quickly but will not start.

Replaced starter motor same problem.

Open idle screw bump start bike runs perfectly.

I am at my wits end hekp would be appreciated.

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FGR01
Posts
6139
Joined
10/1/2006
Location
USA
Fantasy
2/4/2025 2:48pm

Potentially decompression mechanism not working as intended.   Does the starter sound like it's struggling to overcome excess compression?

2/4/2025 7:21pm

Starter clutch?  They get old and slip.

Dampvan
Posts
5
Joined
2/4/2025
Location
Inver, GB
2/4/2025 11:17pm

Thanks for coming back to Me the Ktm 250 SXF does not have decompression , also the clutch is not slipping . Starter motor engages but does not turn over  all the time.

I have read threads with a similar problem  but no one has posted how the issue was resolved..

Since posting I have borrowed a starter motor of a similar bike which works perfectly but on mine struggles to turn over, even bypassing relay cables straight on to starter.

If i back of idle adjustment and zero throttle it will turn over.

Bump starting not a problem runs perfectly.

 

2/5/2025 6:10am Edited Date/Time 2/5/2025 6:12am
Dampvan wrote:
Thanks for coming back to Me the Ktm 250 SXF does not have decompression , also the clutch is not slipping . Starter motor engages but...

Thanks for coming back to Me the Ktm 250 SXF does not have decompression , also the clutch is not slipping . Starter motor engages but does not turn over  all the time.

I have read threads with a similar problem  but no one has posted how the issue was resolved..

Since posting I have borrowed a starter motor of a similar bike which works perfectly but on mine struggles to turn over, even bypassing relay cables straight on to starter.

If i back of idle adjustment and zero throttle it will turn over.

Bump starting not a problem runs perfectly.

 

Its not the starter, it's the torque limiter I bet.  Mine did this and I swapped these from another motor I had,  problem fixed.

https://www.rockymountainatvmc.com/oem-schematic/5?FirstChoice=KTM&SecondChoice=1719&ThirdChoice=1743&assemblySchematic=58410

Part 6

79240016100

(replaces part #
79240016000)

Torque limiter

1

The Shop

Dampvan
Posts
5
Joined
2/4/2025
Location
Inver, GB
2/5/2025 8:18am

Thanks just to be 100% certain , the torque limiter will stop the bike cranking if it has failed. If so looks like its a new Torque limiter

2/5/2025 10:45am
Dampvan wrote:
Thanks just to be 100% certain , the torque limiter will stop the bike cranking if it has failed. If so looks like its a new...

Thanks just to be 100% certain , the torque limiter will stop the bike cranking if it has failed. If so looks like its a new Torque limiter

Yes the starter will spin but it won't engage the motor completely.  

Dampvan
Posts
5
Joined
2/4/2025
Location
Inver, GB
2/5/2025 10:58am

Sorry I did not make myself clear. The starter motor stops completely and the current goes through the roof.There is no whirring noise

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