Camshaft Failure

jjuarez62

New Member
I purchased a new RC390 in may of this year, at 650 miles i went to do my initial service and found the cam shafts to have unusual wear. So i take it to the dealer and 5 weeks later they finally replace the cam shafts. Well now it will not go over 86 MPH so i am taking it to a different KTM dealer. I showed them the pictures of the camshafts and according to them the wear was normal for a 390. Can anyone confirm that this is usual?
 

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fostytou

New Member
The marks should not be there. What appears to be pitting in your 3rd picture would be even more concerning.

Realistically cams should not have any wear or scoring. I've seen bikes with 50,000 miles that are as shiny as a mirror. My 2017's exhaust cams look great (which should probably wear harder than the intake), but my intake cams are scored and I can *juuuust* feel it running my fingernail across the flatter side of the ramp. They looked like this at ~600 miles during the first service and just before 1,000 miles when I decided to take a look again since I was most of the way in there for a PCV install. KTM dealers seem to be suspicious on thier "they never need adjustment at the first service" and "some wear on the cams is normal" comments - time and time again those comments are proven wrong.

One part of the FSM that nobody seems to mention is that it recommends spraying air back through those oil jets on the cam bridge (when you have it off). With the sandy gunk that was in the oil filter/screen (that seems to be on everyone's bike) part of me is worried that some of that is caught in each of the intake jets. Part of me wonders if this is the real reason for the quick first valve service - to check for cam lobe wear due to clogged jets.

After seeing that the cam retails for ~$55 I wasn't motivated enough to take the bridge back off again. I did try to look at it with a mirror and couldn't see anything and tried a quick blast of air but through some tubing - I don't think it had much effect and if something is clogging it then it would probably wind up back in the same place in short order. My thoughts are going to be to check again in a few thousand miles to see if it is worse and replace the cam (and possibly the bridge and jets) if necessary. My main concern is that if I take it on track I don't want something to fail in a corner and cause an injury.

At least one of these other posts seemed to have KTM attribute a clog to extra threadlocker (which could be what that sandy looking stuff is) - but it seems this was not uncommon on earlier bikes:

Anyway, while not confidence inspiring if you are under warranty I'd make a stink about it, if not (like me) I'm just going to follow my plan and check back in and spend the stupid time and $100 to replace stuff if need be and grumble grumble. The biggest pain being that you basically have to do a valve job twice to put in the new cam, then check the gaps, then probably adjust again.


The first picture is at the first service, and the 2nd and 3rd pictures are after another ~400 miles on mine.
 

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