01 400EXC problem

jeb

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#1
Well, I had one of those weekends. I was at a trailride in Northern MN. All arrowed and mapped trails. Lots and lots of fun stuff with probably 60+ miles of trails. It was hot but I've been jogging in the heat so it didn't bother me.

Yesterday, on a loop that I was taking it particularly easy on I was following a buddy in the single track. He's not as quick in the woods so it was an easy pace to keep. About 1/2 mile into that single track I heard something in the engine. So I cock my head and listen real hard for a couple hundred yards and then it suddenly started knocking LOUD. Shut it off immediately. The 3rd of our group rolled up behind and asked if something was wrong.

The engine was leaking a little antifreeze out of that weep hole under the water pump again so I thought maybe I'd blown the seal and lost the antifreeze again. Loosened the cap a bit and AF came out. Once the pressure was gone, I took the cap off and it was full. Let it cool off a bit and started it. Knocking badly. Shut if off. There was really nothing to do for it. I decided to turn around and go backwards to camp as I knew that was only a couple miles. My buddy was going to follow me to the ATV trail and then go chase the first guy down and, I thought, come check on me.

I went about 200 yards and decided it was making too much noise. Plus, AF was RUNNING out of the weep hole now. So I shut it off and started pushing. Good thing it's so flat up there. I figured I'd have my buddy tow me back with a rope I carry but he never showed. I assumed we had mis-communicated but it turns out it took him 15 minutes to get his WR250F started. By the time he got to the ATV trail, I'd pushed it beyond that point so he went to find the other guy thinking I'd ridden it out.

Now, imagine my little private hell here. It's hot (95f), it's humid, it's
sunny, I'm totally depressed and I'm pushing the most fun bike I've ever owned out of the woods. It was just rolling terrain with some sandy whoops for variety. I thought pushing it up slope through the whoops would be the worst but it turns out the long flat sections in the sun were the bad spots. If I stopped and rested, it was worse. The heat would just make me drip like a wet dog. So on and on I pushed. Of course, nobody ever came by during the whole deal. I figured I pushed for about 1.5 - 2 miles. The last piece on a gravel road sucked because it's a long up slope back to camp. My buddies showed up about 1.5 hours after I got back. They rode out the entire fun loop instead of taking the shortcuts back.

I'm pretty sure something happened to my camshaft. It's the only thing that makes sense. The waterpump seal and impeller are right on the end of the camshaft so for it to start leaking without having overheated it only makes sense that the problem lies there. I trace this back to my having overheated the bike badly GPSing at our clubs trail this spring.

Details on that incident. I was still getting used to the bike and I'd never had it overheat. I'd replaced the hose clamps on the stat like a good boy before I ever rode the bike. So we're working through the trail and getting around a lot of blow downs and 'whoosh', it steams and overheats. I wasn't happy about it but thought it was just hot. I rode for a while like that until I heard some knocking. Shut it off to find the bottom clamp had blown off the stat anyway! I fixed it on the trail and my camelbak exactly filled the bike. It ran fine after that.

It seemed like I had more engine noise after that incident, though, so I've really been a little suspicious ever since. Plus, no one else seems to have had this problem. The RFS's seem pretty bullet proof from everything I've read.

My 99 250EXC used to boil an ounce or two on a hard ride and it dumped it on the pipe so I didn't give the steam bath the import I should have. Moral of the story is if your RFS boils/steams and you've been following the don't let it idle for more than a minute rule, shut it down and look at those hose clamps. There's apparently a lot of pressure in the line coming into the bottom of the stat housing.

I'll have to tear it down to even begin to diagnose it. I'm hoping for camshaft bearings but fearful it will involve replacing heads and cams. Any advice gladly taken.
 
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#3
From the rumors and innuendo dept.:

I’ve heard of a few of these bikes haveing the cam bearings fail prematurely. I think they may be changing this part for ’02.

Just what I heard...

Here
 

Strick

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#4
Jeb,

To follow up on Hick's comment, I cut this from the EuroKTM site. These are changes being introduced in the 2002 models:
400 / 520:
1. New output shaft sealing.
2. Improved and strengthened ignition and clutch covers
3. Improved clutch offering improved lifetime and maintenance periods.
4. Camshaft bearing now sealed with an improved seal carrier designed to prevent the 'O' ring being squeezed during assembly.
 

Max Factor

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#5
There's quite a bit of talk about this issue on many of the 'boards'. It seems they are failing both 400's and 520's. 2000 and 2001 models. Anywhere between 100 miles and 2000 miles, all over the world.

It's a bit of a worry, especially if KTM are making a 2002 change to the bearing. That tells me they recognise the issues as a design problem not a sparatic bearing failure, or even a 'bad batch' of bearings

Which begs the question.......Should I go out and change the Cam Bearings on my 520 right now even if they're not suspect?? Call it 'Preventative Maintenance'

The thing that always cheezes me off with dirt bikes is that if this were a Road Bike issue, there would be a recall issued and the dealers would retro fit all existing models with the update. But no, dirtbikers will just get shafted by dealers ignoring customers and voiding warranties for the sake of them saving money.
 

jeb

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#6
Great responses and info. Thanks guys. My bike was new in Feb but I've only got about 1000 miles on it. All of the rides have been trailrides. Aggressive trailrides when with the boys, though. I just haven't had time to ride as much as I like this year. Just too much going on.
 

jeb

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#7
Originally posted by Strick
Jeb,

To follow up on Hick's comment, I cut this from the EuroKTM site. These are changes being introduced in the 2002 models:
400 / 520:
1. New output shaft sealing.
2. Improved and strengthened ignition and clutch covers
3. Improved clutch offering improved lifetime and maintenance periods.
4. Camshaft bearing now sealed with an improved seal carrier designed to prevent the 'O' ring being squeezed during assembly.
Strick, can you give me a link to the site that has that info. I tried the euro KTM site and the eurotekktm site but couldn't find it.
Thanks
 

Strick

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#8
Jeb, you didn't bump your head at that Minnesota Hillclimb, did you?

Go to www.eurotekktm.com
-click on enter
-on rt of screen click on KTM motorcycles, a pop down menu will appear
-click on KTM 2002 model preview
-scroll down to KTM 2002 RFS update AND VOILA'
 

Strick

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#10
FYI

Jeb, I checked with our local KTM, who sold 21 rfs last year. They had 1 bearing issue. It was very similar to your description.
 
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#11
My local dealer got in touch with KTM Canada and they are not aware of any bearing related failures on any 00/01 RFS in the whole country. Not to say that there hasnt been any, but no one seems to know about them if there have been.
 

jeb

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#12
The problem does seem very sporadic. I don't think anyone really knows why. Here's what I did to fix it.

I declined KTM's offer to help. The problem is that my local dealer could no way handle the job and the other dealer is over 2 hours away and not real thrilled about working on a bike I didn't buy there, even though I've purchased 3 bikes from them in the last 3 years. Truth be told, I really prefer to do the work myself, anyway.

I already had all the waterpump seal parts so all I needed was the bearings and a flywheel puller all of which I aquired Friday. I've already done the WP seal once so the steps, for the most part, were familiar.

Drain and remove radiators and hoses. Lock the crank at TDC with the bolt. Unhook the head oil line. Remove the valve covers. Remove the left side rubber tank mount. Remove the waterpump cover and impeller. Remove the decompressor cable. Remove the rocker box cover.

Now I can see the damage. The right (brake) side bearing is gone. The races are all that's left. Lot's of shrapnel in the top so I start in with the magnet before I go any further and get what I can.

Remove the camchain tensioner bolt. Remove the flywheel cover (what a mess! oil all over the place.) and flywheel so I can unbolt and lower the plastic chain tensioner. Lift the cam chain off the cam and take the camshaft out.

Close inspection shows no collateral damage to anything that I can tell. And I'm picky. The KTM bearings (2) I got are the updated parts. They're sealed and look just like wheel bearings. I'm sure the local bearing house ones would've been fine. Kind of odd to put sealed bearings on a cam that has an oiler right over the top of it.

Pull the old bearings off, or what's left of the one. Press new one's one along with all new WP seal parts and reinstall cam, chain (watch those timing marks on the sprocket) and plastic tensioner. Clean all the gasket surfaces and apply a coat of gasket maker to rocker box cover and install. Set radial play on rocker arms before tigtening.

Set valve gaps (they were off) and reinstall valve covers. Put impeller, pin and clip on and installed cover. Installed tensioner, flywheel, FW cover, etc. Drain oil and pull screens and filters. Flush engine with kerosene and let it dry.

Fill with oil and fired it up. All right! Talk about a quiet running motor! I don't think it's ever been this quiet. Part of that may be that I left the CF skid plate off for now since I plan to change the oil several times in the next few miles to get all the junk out before it does any harm. This is when I'm happy that KTM put in 2 filters, 2 screens and a magnetic drain plug.

Test ride was awesome. I have my bike back and all whole and I couldn't be happier. $30 worth of parts was the total bill. Flywheel puller was $45 but that doesn't count to me. I'll use it again so it's just another tool cost.

Thanks to all that helped. I could not have done it without all the information. You guys are great!