ktm starter problem long shot here?

Mar 9, 2017
232
47
28
stillwater MN
My buddy has a 14 ktm sxf 450 that turns over really slow. I put a new battery in and checked wires and it still turns over really slow and or should i say hard. It seems like it has no decompression release or something else is wrong like free wheel clutch? Anyone have a service manual or ideas? Once you get it running it runs fine.
 

dooman92

Well-known member
Lifetime Membership
Mar 1, 2010
564
154
43
Those bikes had issues with the ground circuit. Resistance in either positive or negative side will cause that issue. A voltage drop test is easy and best option, other than cleaning the ground connections, to determine if circuit resistance is at fault. Starter draw amperage on that unit should be 70ish amps or less. If you search voltage drop or starter draw might locate long post that covered both. Good luck.
 
Mar 9, 2017
232
47
28
stillwater MN
Okay I cleaned up connection. No voltage drop anywhere. I talked to the guy that sold it to him. I just found out it is a big bore with high compression piston. I do not trust taking this thing in backcountry without better cranking. I guess he will be looking at more powerful battery and or starter. Any ideas on what may work?
 

wwillf01

Well-known member
Lifetime Membership
Aug 12, 2012
2,522
419
83
40
Heber Ut
I am assuming you are using a zero weight oil.....

Sent from my SM-F900U using Tapatalk
 

dooman92

Well-known member
Lifetime Membership
Mar 1, 2010
564
154
43
Does it spin over easily with the spark plug out? If the starter is defective it may spin slow without compression. I'm assuming no kick start for evaluation of compression. Have you tried a known good battery or load test the one you have? Does battery voltage hold above 10 volts while cranking? If you have an inductive pickup meter pretty easy to check for current (amp) draw while cranking. My 18 500 with high compression piston spins same as stock. As I recall it drew about 70 amps while cranking.
 

Coldfinger

Well-known member
Lifetime Membership
Nov 26, 2007
2,167
426
83
Nebraska
My street bike, Yamaha Raider, needed a new starter.
I bought the bike with 1,000 miles.
It always cranked slow. I thought it was just nature of the beast being a big twin.

After many years of slow cranking, I pulled the starter motor off and took it apart. Very easy to remove starter and disassemble on this bike.

I saw right away that 1 large magnets on the starter housing was cracked in half.

I replaced the starter and couldn’t believe how much easier it turns over the engine now.
 
Feb 4, 2011
111
175
43
+1 on broken magnets inside the starter. Saw one go out this winter. We were able to take it apart in the field, remove the broken pieces, put it together and there was enough still there to turn the thing over. Good thing, fucking bikes don't have kick starters anymore. WTF is up with that? Oh well, different thread on that complaint I guess.
 

dooman92

Well-known member
Lifetime Membership
Mar 1, 2010
564
154
43
In that video, initially it sounds like the starter is spinning but the engine is not turning over. Then on second try it turns over? That would imply that the one way clutch is slipping, forget what ktm calls it, but engages to crank engine and then free wheels when crank turns faster than starter.

When it turns over with no plug does it spin at same speed/revolution as with plug in?
 

dooman92

Well-known member
Lifetime Membership
Mar 1, 2010
564
154
43
Have you pulled the right side cover and watched what happens when the starter is engaged? I suspect the starter clutch is slipping then catching. The starter clutch is under the main gear on the end of the crank. Ck YouTube, might be video 450 ktm starter clutch.
 
Premium Features