2007 450 sx-f engine issue?

[canucklehead]

My son was riding his '07 450 SX-F and heard a nasty metal on metal noise, then it stopped running and wouldn't start. He described it as sounding like a bucket of bolts being shaken around in a blender.

Oil had been changed regularly with synthetic. Valves were just checked and within spec (altho tight end of spec). Prior to this we had a bit of a rattling sound (some might even call it a tick noise, but more of a rattle). My cousin has owned many KTMs and he said the noise was clutch basket, not top end. He said KTMs often had noisy clutch basket issues (at least his 525 & other models always do). Another person who knows nothing about KTMs thought that noise was top end/valve. The rattle noise could be coincidence, or related.

So where do I begin on this? Do timing chains let go? Compression test it?

thanks for your help.

[tye1138]

Sounds to me like you've got a failed chain tensioner. Why the bike won't start is because the timing is just a tiny bit off and the noise you heard was the chain flapping around the crank case.

First thing I'd do is verify this, which should be as easy as pulling out the tensioner and seeing if it holds up to any pressure with your finger. You can also pull the cam cover off and see if the chain is truly tensioned.

Its a very common problem on the F's, especially of that generation.

DO NOT ATTEMPT TO START THE MOTOR

Pull the spark plug cable to insure it doesn't start!!!

[canucklehead]

thanks for the info. I was wondering about cam chain.

err, ahh... what happens if we already tried to start it and it didn't start? Would it cause valve damage? It definitely has NOT fired since this happened, but he did push the starter button to try to turn it over.

I'm assuming I can re-time cams & crank. But when things get out of time, doesn't that destroy valves?

Is the tensioner the issue, or is the cam chain stretched and in need of replacement?

I just replaced the cam chain on my other son's suzuki Z400 quad, and they're well known for stretched cam chains aswell.

maybe I'll become good at cam chain replacement.

Another KTM guy told me the oil pump parts were cheap in the '07 year, but improved later on (2010 model??).

[tye1138]

It depends on the hours of the motor.

Usually the tensioner fails, that is between the crank and the cam's. So two things could happen, one of which is the chain could skip a tooth leaving more gap between the two cam's and knocking the timing off by 10 or so degree's on either side, so 20 total... that will basically bend the valves. The other of which (which is what I think happened) is the chain is loose between the cams and the main timing shaft. What that will do is change where the valves are completely closed. So they might be open just a crack on the compression stroke and its not firing up.

I hope you don't have bent valves, my guess is you won't.

I also don't think the chain is stretched, that requires a LOT of hours. But then again, the 450 was never designed for supermoto, so it COULD be an issue that I haven't heard of based on the supermoto application. No dirtbike motor likes to be revved to supermoto RPM's for that long of a time, so things like this can happen sadly.

Ohh and I doubt its the oil pump, though your right, there were oil pump issues on that generation.

[canucklehead]

first of all Tye, thanks very much for taking the time to educate me and help me out.

DOH! I only referred to the oil pump as a throw-in comment cuz I've heard that's something I should address & deal with.

I posted in Supercross because I was told that's what a 450 SX-F was designed for. My son traded his 525 KTM Outlaw quad for this bike. He's ridden it for some hill climbs, trail riding and I tried to tell him from the start to get something like an EXC, or even a wide range tranny type bike. Alas, 15 y/o knows more than the parent.

So riding-wise, I doubt he's revved it ridiculously hard. And while he's ridden some trails and had fun with it, I don't think they've been hard hours compared to how others might ride it. I think the hours are relativley low, maybe medium. Not hard hours.

After I read your post I went to ebay and KTM parts on-line. I found this "Dirt Tricks" brand automatic chain tensioner. Amazingly, the seller is in my area (what are the chances of that!!). seems they indicate you have to lay down bike to take tension off to replace/install. Anyways, I am jumping the gun. I'll look at it first.

here's a link for the after-market tensioner: http://www.ebay.com/itm/KTM-Timing-C...item20bda0a1e6

So would the few attempted starts after this happened cause any other damage?

thanks!!

[tye1138]

Ahh ok, if its been ridden in the dirt, its just a tensioner. It fails without any abuse, just gives up the ghost all of a sudden.

So yea, check the old one first, make sure you inspect it well, take the cam cover off, etc.

Once inspected and you know thats the problem, then I'd pick up an aftermarket one. Buy one from a KTM specialist, not from ebay, thats way too scary.

In terms of it damaging something... once the pistons hit the valves, you've got problems. Usually they bend very slightly and then won't seat properly and leak. If the piston hits them harder, then you could bend the valve stem and mushroom the end, which means they won't even come out! Worst part is, you won't know you did damage because the forces of the piston hitting the valve is so great, with the starter motor turning it over, it will just keep on spinning. Which is one nice thing about a kick start, you would feel it in the lever.

So, fingers crossed... thats the best you can do!

[canucklehead]

assuming I get the tensioner replaced and re-time it, will it be immediately obvious if I have bent valve/issues going on there?

Can I manually turn crank to see if there are issues/rubbing, etc..?

will I do more damage running it, if there is a problem with valves?

should I pull head off and take it into machine shop?

I know the starter cranked over several times, so not sure if piston hit valves or not.

Do you think the rattling noise we were hearing for a long time before all of this was poor cam chain tension, or clutch basket ?

geez I ask too many questions!!

[tye1138]

Originally Posted by canucklehead

assuming I get the tensioner replaced and re-time it, will it be immediately obvious if I have bent valve/issues going on there?

Yes, it won't start. You can also do a compression test or leak down test to verify its condition.

Originally Posted by canucklehead

Can I manually turn crank to see if there are issues/rubbing, etc..?

Its hard with the compressed valve springs to tell anything really, unless they were mushroomed. If they were mushroomed, the motor would not turn over as when the cam hit the valve, it would simply stop dead in its tracks.

Originally Posted by canucklehead

will I do more damage running it, if there is a problem with valves?

If my diagnosis is correct and its just the tensioner, the valves are probably OK. If they are OK, obviously you'll be fine. If the valves arn't OK, you won't want to be running it, assuming it starts. Yes, you will do more damage because the valve will start to damage the seat.

Originally Posted by canucklehead

should I pull head off and take it into machine shop?

IF you determine you've got bent valves through a compression or leak down test, then yes you will want to take the head off and send it to a KTM specialist, someone who builds KTM race motors for a living. You do not want to send it to a generic machine shop. It might cost you a few extra hundred bux in the long run, but its WELL worth it.

Originally Posted by canucklehead

Do you think the rattling noise we were hearing for a long time before all of this was poor cam chain tension, or clutch basket ?

A worn clutch basket does not make much noise, just a small chatter coming from the clutch area itself. The clutch basket is a dull chatter, the timing chain is a loud, metallic rattle emanating from all over the side of the motor.

Originally Posted by canucklehead

geez I ask too many questions!!

No worries, its all pretty straight-forward stuff!

[canucklehead]

thanks for the info. I am going to have a look at this tonight/tomorrow.

The tensioner on our 525 KTM and the Z400 were both the self-adjusting ratchet/tooth style. It was easy to see how many notches the tensioner was at. This KTM one is hydraulic (?). So when I remove it, you mentioned I can push on it to feel for pressure? Doesn't it need to be loaded up with oil?

I should pull the head cover off and push on the chain? I'll also see if I can set piston to TDC and see where the cams are at.

Compression test... I have a compression tester. I recall the spark plug was a major PITA to get at. What's it like to get a compression tester in that deep hole with the frame in the way? any tricks?

[tye1138]

Originally Posted by canucklehead

This KTM one is hydraulic (?). So when I remove it, you mentioned I can push on it to feel for pressure? Doesn't it need to be loaded up with oil?

http://motocrossactionmag.com/KTM/Ne...SION-2653.aspx

Hmm, I honestly hadn't thought about that, I'm so use to the ratcheting type. Now I'm kinda confused on what to do next....

Originally Posted by canucklehead

I should pull the head cover off and push on the chain? I'll also see if I can set piston to TDC and see where the cams are at.

Normally, I'd pull the tensioner and make sure it was working properly. But this tensioner needs the oil pressure to work and that means it must be running to test.

So probably the best thing to do is get the motor at TDC and see where the timing of the cam's is.

Originally Posted by canucklehead

Compression test... I have a compression tester. I recall the spark plug was a major PITA to get at. What's it like to get a compression tester in that deep hole with the frame in the way? any tricks?

What we usually do is buy a piece of the right diameter metal piping from a hardware store, cut it short, put the correct threads at both ends and basically make an extension. KTM has a tool you can buy which does this function, though I bet its a bazillion dollars.