2013 450sxf failure

[chumbilly1]

So bike had been getting a little slow to start. Gave it up last week. Had to leave it in the mtns for 4 long days till I got the right group of mtn sledders together for rescue. Got it out yesterday. Bike started while being towed by a sled, but ran really rough till warmed up completely. Then idle was weak and would not restart unless compression started, not even with ether. Took valve cover off tonight and verified clearances at valves. All are within spec. Bike has 62 hours on it total, 38 on snow and Im the original owner. I ordered new Wiseco racers choice Hi-comp piston kit for it and im hoping bore is still good. Any guesses on what failed? I looked at piston crown with fiberoptic scope and dont see a crack. Im betting on seriously eroded compression ring or hoping anyway. Anyone's Ktm 450 fail like this? I have seen 450 pistons crack inline with wristpin before, but I cant see that on a KTM with 62 hours. If it is rings and bore is good I will be back out on Saturday. Crossing my fingers.

 

[sidehillsam]

Oil Sparklies

Curious what your oil looks like. My 18 501 has aluminum flakes in the oil. I've been told this is scuffing off of the piston, and once it starts it never stops. If something is going away in the motor, it usually ends up in the oil.

 

[M5-]

Hairline crack in the piston is my guess. Are you running advanced timing. What fuel do you run. Service life on a 4T race bike top end isn't all that long if you follow the recommended interval.

You hear guys say they have 200 plus hours on their snow bikes, I say good luck with that plan.


M5

 

[chumbilly1]

Oil looks pretty good, although it seemed to use a bit in the 4 mile downhill ride to truck. I have seen some sparklies before I think. I change oil every 6-10 hours. As for timing. Ugh. I installed a Raze wingman with ninja backup kit this spring. Ran amazing for 1.5 hrs. Then the hard starting began to show its head. I never activated the N2O in the time it ran well. Have tried since and the system will not activate. evidently it knows something is awry.

 

[chumbilly1]

Hairline crack in the piston is my guess. Are you running advanced timing. What fuel do you run. Service life on a 4T race bike top end isn't all that long if you follow the recommended interval.

You hear guys say they have 200 plus hours on their snow bikes, I say good luck with that plan.


M5

I was thinking about the Fuel question. I run 92 pump as a snowbike, however in the bikes first life it was my Desert steed, and I ran a few cans of U4.4 through it. Is that highly oxegenated fuel harder on topends? Also I know that the service intervals for race motors are short, what do you think is realistic? I am definately asking alot from the motor on the snow. Also, Isnt it strange that the piston/rings would fail before it ever needed a valve adjustment?

 

[byeatts]

Oil looks pretty good, although it seemed to use a bit in the 4 mile downhill ride to truck. I have seen some sparklies before I think. I change oil every 6-10 hours. As for timing. Ugh. I installed a Raze wingman with ninja backup kit this spring. Ran amazing for 1.5 hrs. Then the hard starting began to show its head. I never activated the N2O in the time it ran well. Have tried since and the system will not activate. evidently it knows something is awry.

plug in the stock ECU and try. could be a failure in the altitude sensor

 

[boondocker97]

Hairline crack in the piston is my guess. Are you running advanced timing. What fuel do you run. Service life on a 4T race bike top end isn't all that long if you follow the recommended interval.

You hear guys say they have 200 plus hours on their snow bikes, I say good luck with that plan.


M5

^ I'm with him if it is low on compression. From my own experience and what I've read on KTM forums the pistons will go long before valves need replaced. I'm on my 4th piston in my 505sxf race motor and only ever adjusted one valve. The Del West Ti valves KTM uses will run hundreds of hours as long as they never see dirt ingestion. IMO a snowbike that is ridden hard is basically seeing full race loads put on the motor so you're going to want to stick closer to the recommended rebuild intervals.

 

[chumbilly1]

^ I'm with him if it is low on compression. From my own experience and what I've read on KTM forums the pistons will go long before valves need replaced. I'm on my 4th piston in my 505sxf race motor and only ever adjusted one valve. The Del West Ti valves KTM uses will run hundreds of hours as long as they never see dirt ingestion. IMO a snowbike that is ridden hard is basically seeing full race loads put on the motor so you're going to want to stick closer to the recommended rebuild intervals.

10-4 on the race loads. Im gonna be alot more on top of it if i continue to run a 450 snowbike. I just figured it would need valve adjustment first. Caught me off guard. I guess im about to find out what 14-1 runs/lasts like in the snow. Hoping i will be able to rev a little less with this set-up. Doubt it though

 

[Misha Subo]

KIS(S)

Can't help as we that have 2Ts don't seem to get these problems. They're simply too simple.

 

[chumbilly1]

Can't help as we that have 2Ts don't seem to get these problems. They're simply too simple.

Yea, I have a 300 as well with a 129SS on back. Trust me, they have piston life spans as well!

 

[byeatts]

Yea, I have a 300 as well with a 129SS on back. Trust me, they have piston life spans as well!

Jus sayin I had failures on the competitors ECU,s., Didn't actually see you had completed a compression test.

 

[chumbilly1]

Jus sayin I had failures on the competitors ECU,s., Didn't actually see you had completed a compression test.

I appreciate that advice and initially thought that I had mapping issues. However it has become evident that my problems are internal.

 

[n16ht5]

mine did that, coolant temp sensor

 

[chumbilly1]

mine did that, coolant temp sensor

Are you saying my symptoms are the same as when your coolant temp sensor went out?

 

[chumbilly1]

I should add that the day the bike gave up was a deep warm day in the cascades. There had been 60" of new that week in the area we were riding. My riding buddy and myself were laughing about how well the bikes would go uphill through the trees in first gear pinned. Right before she quit, I did a longish third gear pull up a roadbed, jumped off of a pillow of snow into the deep stuff and she just quit. Under full load. Blew a couple smoke rings, then drained the battery and two jumppacks to no avail.

 

[M5-]

If you haven't already done one I'd be inclined to do a compression test before I tore it down. Being that you have a piston coming and 62 hours you might as well throw it in there but it would be interesting to see what the compression is before hand.


M5

 

[chumbilly1]

If you haven't already done one I'd be inclined to do a compression test before I tore it down. Being that you have a piston coming and 62 hours you might as well throw it in there but it would be interesting to see what the compression is before hand.


M5

I don't have a compression tester that will fit that damn tiny sparkplughole. Also doesn't the decomp can make it impossible to test accurately?

 

[wwillf01]

I don't have a compression tester that will fit that damn tiny sparkplughole. Also doesn't the decomp can make it impossible to test accurately?

Leak down test....... for sure just to see where your at.

 

[byeatts]

So bike had been getting a little slow to start. Gave it up last week. Had to leave it in the mtns for 4 long days till I got the right group of mtn sledders together for rescue. Got it out yesterday. Bike started while being towed by a sled, but ran really rough till warmed up completely. Then idle was weak and would not restart unless compression started, not even with ether. Took valve cover off tonight and verified clearances at valves. All are within spec. Bike has 62 hours on it total, 38 on snow and Im the original owner. I ordered new Wiseco racers choice Hi-comp piston kit for it and im hoping bore is still good. Any guesses on what failed? I looked at piston crown with fiberoptic scope and dont see a crack. Im betting on seriously eroded compression ring or hoping anyway. Anyone's Ktm 450 fail like this? I have seen 450 pistons crack inline with wristpin before, but I cant see that on a KTM with 62 hours. If it is rings and bore is good I will be back out on Saturday. Crossing my fingers.

I had a ECU fail and it would barely start ,popped rattled and would not rev at all, sounded like a toast motor, Failure in the altitude sensor and the throttle calibration.we even had flames coming out the exhaust, Cant believe you didn't toss on the stock ECU to at least dismiss ,,

 

[chumbilly1]

I had a ECU fail and it would barely start ,popped rattled and would not rev at all, sounded like a toast motor, Failure in the altitude sensor and the throttle calibration.we even had flames coming out the exhaust, Cant believe you didn't toss on the stock ECU to at least dismiss ,,

Mine doesnt have those symtoms. It has low comp. I would have changed my ECU, however I had to change to a newer harness to use the GET ECU, and now I cannot plug in my stock ECU. If I am jumping the gun on Piston replacement, OH well, live and learn. Had bar tabs bigger than that quite frequently in my youth