KTM 450 EXC Question

A buddy of mine lives in New Zealand. Trying to offer a bit of guidance. I don't think this is a failure, but I'm not knowledgeable enough in KTMs to be sure.

Any ideas from you experts out there?

Well, ****. No pictures. I'll have to fix that. Give me a minute.

See if they're here now:



to me, this looks like it's by design. if it was any sort of damage, there's no way it would be that perfectly shaped. He says it's the bearing race. I don't think it can be. Might be where the bearing race goes, but it's not he race itself.

What say you?

Shoot Rsquared a PM with a link to this thread. I'd bet a lot of money he will know.

Apparently, he popped it off with some special tool heated to 150 degrees. Said that was the race, and found some pix on the Interwebs showing the progressive deterioration of the race. The damage just seemed too perfect to me - then again, I don't know exactly how that motor is put together.

So no biggie. Now he's looking for bearings.

The parts fiche for the engine shows that a roller bearing goes on the shaft right there. A bearing "race" typically refers to the groove on the inside of the bearing that guides the balls as they roll. That would be internal to the bearing, not on the mating surface between the bearing and the shaft. Also, it should be a full circle, not partial, unless it was one half of a plain bearing.

Everything I can find shows how to use heat to expand the entire roller bearing to make it release from the shaft so that the entire bearing comes off the shaft in one piece. There is nothing left on the shaft.

Can you get a link or two from him where he found the info? I would be interested in seeing it.

The inner race stays on the crank. If you look close at the picture you can see the bearing number at about the 11 o'clock position.

Here is a video of a race being removed from a 640 crank.
[ame="https://www.youtube.com/watch?v=ZQARSuXakDA"]KTM 640 Crank Race Removal.wmv - YouTube[/ame]

I found that same vid Gary. But I don't see the rough surface shown in the pics on the one in the video Also, doesn't a race usually have some kind of groove or lip that holds the balls/rollers in place? I would never expect to see that rough surface, which looks like it has been shot peened, on the INSIDE of a bearing with the balls/rollers. So what is that?

Tourmeister said:

I found that same vid Gary. But I don't see the rough surface shown in the pics on the one in the video Also, doesn't a race usually have some kind of groove or lip that holds the balls/rollers in place? I would never expect to see that rough surface, which looks like it has been shot peened, on the INSIDE of a bearing with the balls/rollers. So what is that?

Click to expand...

http://www.bearingsrus.co.uk/nj206ecp-c3-skf
Here is a picture of the bearing for this application. The race is not captive in this instance. The inner race is interference fit to the crank while the outer race and rollers are interference fit to the case. The shims that were behind the inner race in the video set the clearance for the crank. This dimension is critical as this bearing is not designed to take any loading from the side (These are rollers not balls). This type of failure is usually from a crank that has spread or twisted. Once the crank spreads or twist it puts lateral forces on the bearing that damage the hardened surface of the race or a roller. It will eat itself to destruction if not caught quickly.

Bike that are prone to this are Super Moto bikes that have lots of traction and on and off the throttle quickly. This constant action causes the crank to flex a lot. The other place you see crank spread is big bore kits with high compression.

Here is a link with some pictures of bearing failure. These are all different types, but some good examples.
http://jadanalysis.co.uk/bearing-failure-faqs

That is typical for a galded bearing in a high stress application , the damage is during the power stroke . The cause of that is lubricant failure . As the piston fired it puts major pressure on the crank and the only place it can go is to rotate under extream pressure . The oil was not healthy enough to stay between the bearing rollers and the race . There is probly matching damage on the inside of the race too . Any way with all the metal that flaked off everything in that motor is contaminated . I would not recommend rebuild without some serious inspection of every moving part in it . I would expect a good used motor could be found cheaper . If that race were defective from the factory the other side of it that is opposite the worn part would be soft metal and easily scratched with a file . If that is the case it would be worthwhile to have a hardness test done and if it fails some ammo to go back on KTM for warranty . I doubt that's the case . Every time that motor fires it hammers those two bearings against each other . The oil is supposed to be the cushion . After one chip it grows with every reveloution . I have seen transmission bearings come out of truck transmission looking like that when worked hard and filled with havonline gear oil . I would defiantly have reservations about continuing to use the oil he has been using , that is a prime example of the oil not doing what it should . If there is damage to the rollers and inside race . There is no doubt of lube failure , if the rest of the bearing is fine it could be a race that missed the mark in hardness and should have been rejected by quality control,

So in the pic, it looks like the rough surface is raised above the machined surface. Is this the result of the metal flaking and literally rising up from its original location? And, as David mentioned, you only see it on part of the circumference that experiences loading during the power stroke? Like Scott mentioned, it just looks so precise in its outlines that it is hard to believe it is just the result of wear. But I am not a bearing expert and have not examined many, other than when all the balls, retaining ring, seal, and oil in the final drive of my 1150 GS fell out all over the ground when I removed the wheel

The worn area is probly .030 thousands deeper than the clean surface and if it was hardened material as it should have been it all came out in chips so all those chips have been circulating thru the lubricating system till they got filtered out in the oil filters . I had some high stress bearings break on a husky I had years ago but I would open it up pull the broken gear out and keep riding , it didn't do the rest of the motor any good so it lived a short life .

Sounds like advice worth 199.00 an hour! It saved them a lot of running around.

What year was the bike? Estimated mileage / hours on bottom end?

As previously stated, that is a classical bearing failure. As also stated a lot of fine metal particles will have circulated with the oil around the engine, unlike the suggestion above to find another engine, I would keep the current engine, but I would be dismantling the gearbox/engine and very carefully checking all bearings/gears for wear/contamination, then power wash all bearings/crankcases and replacing any plain bearings, plus blow out all oil passages to remove any residue or particles that are lying around. Then carefully reassemble motor and use a good synthetic motor oil and oil filter. Definitely power wash the big end bearings as those little bits of metal will have found there way into the bigend and could have done a lot of damage, I personally would be pressing the crankshaft apart and replacing the big end bearing for peace-off-mind.

Gary

Thrasherg said:

As previously stated, that is a classical bearing failure. As also stated a lot of fine metal particles will have circulated with the oil around the engine, unlike the suggestion above to find another engine, I would keep the current engine, but I would be dismantling the gearbox/engine and very carefully checking all bearings/gears for wear/contamination, then power wash all bearings/crankcases and replacing any plain bearings, plus blow out all oil passages to remove any residue or particles that are lying around. Then carefully reassemble motor and use a good synthetic motor oil and oil filter. Definitely power wash the big end bearings as those little bits of metal will have found there way into the bigend and could have done a lot of damage, I personally would be pressing the crankshaft apart and replacing the big end bearing for peace-off-mind.

Gary

Click to expand...

You must have mad motor working skilz! Most of that is beyond my technical knowledge and the contents of my tool box

That's why replacement is a better option unless you just really have time on you hands and lots of nice toys in the garage . And can inspect and be sure every part of the motor is satisfactory for reuse . Normally after a catastorfic failure its much cheaper to start over with a known running motor . I have a scrap iveco diesel motor on a shelf that the stupid operators rolled the tractor over , it took them a hour to upright it then they tried to start it . The oil had seeped in on top of one piston so the rod got buckled then broke . It broke the block where it hit . The dealer quoted to repair it for 15 k , I told them to replace it and send me the old motor . That cost 20 k . Good thing I did , when I looked at it the counter balancer had been hitting the crankshaft when they ran it that could have gotten exciting had they reved it up . Besides I needed some spare parts for other motors . All the top end was good , it only had a thousand hours on it , barely a year old .

Thanks, all. Cagiva 549, I posted your response to his FB thread. I'm not sure he thought about (basically) total engine destruction. I only know he was looking for bearings. But you're definitely right - the bearings came apart under stress, and parts of them will be everywhere. Might be impossible to clean it all out. And, the worst part, if you don't get it all, you're just waiting for the next failure.

So we'll see what happens. If there's any interest (and I actually find anything out), I'll let you know.

Tourmeister said:

You must have mad motor working skilz! Most of that is beyond my technical knowledge and the contents of my tool box

Click to expand...

Scott, I wasn't saying I have all the tools to do that, but there are a lot of companies around that will do it for a modest price, if the owner is capable of completely stripping the motor down and reassembling it, plus check bearings for wear (just needs a micrometer) I can definitely strip and rebuild a motor, send a crank out for a rebuild and find a local shop with a power wash to clean all casings and oil ways, I would assume that would be cheaper than a replacement engine with unknown history.

Gary

Thrasherg said:

Scott, I wasn't saying I have all the tools to do that, but there are a lot of companies around that will do it for a modest price, if the owner is capable of completely stripping the motor down and reassembling it, plus check bearings for wear (just needs a micrometer) I can definitely strip and rebuild a motor, send a crank out for a rebuild and find a local shop with a power wash to clean all casings and oil ways, I would assume that would be cheaper than a replacement engine with unknown history.

Gary

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This would be my approach also. Even if the cost is slightly more than a used engine you know what you have. In the past I have bought used engines and torn them down for inspection before running them. In the end each one must consider what they are capable of and comfortable with. No right or wrong answer, just different choices for different situations.

Maybe it has to do with your name.....LOL

Gary