Cam lobe failure? (pictures attached) K49 2017

[jpdopaco]

Hello everyone,

I'm writing to discuss my XR, which has been exhibiting a pronounced engine ticking sound across the entire rev range. The bike has covered 68,000 km and has a complete service record with BMW. Notably, about a year ago, at 61,000 km, the cam chain replacement (Kit) was undertaken, and this information is documented in the service record.

While I've gone through other discussions on a similar matter, I've yet to come across a situation quite like mine.

Approximately one and a half months ago, the bike underwent a simple check-up and servicing (including oil and filter changes) at a BMW dealership. No issues were reported during this service.

However, last week I started to notice a conspicuous ticking noise. Initially, I assumed it was emanating from a 2-stroke bike that was riding ahead of me. Strangely, even after the 2-stroke bike moved away, the ticking sound persisted. I decided to cautiously ride the bike back home and park it.

In an attempt to diagnose the issue, I decided to inspect the valve cover and assess the valve clearances, all of which were found to be within the specified limits. As I was in the process of reassembling the valve cover, I couldn't help but notice a disparity between the left intake camshaft lobe on cylinder 2 and its counterpart on the right side (please refer to the attached pictures). I'm seeking your opinion on whether this could be an early indicator of camshaft failure. Unfortunately, I wasn't able to examine the rocker arm since I lack the timing tool mentioned in the Haynes manual. If there's an alternative method for setting the timing, I would greatly appreciate your guidance.





Thank you for your assistance.

[Antares]

Right is normal, left is hard to tell but at 68k km it's definitely not a faulty cam to look like that. Might be wearing down. My advice would be to take a mental note, close pictures, feel for a lip on the edges of the cam lobe, measure even, then have another look in a couple thousand km to compare. Removing the camshaft to get a look at the lobes might also be advisable if you have time and not in a rush. 

[jpdopaco]

Originally Posted by Antares

Right is normal, left is hard to tell but at 68k km it's definitely not a faulty cam to look like that. Might be wearing down. My advice would be to take a mental note, close pictures, feel for a lip on the edges of the cam lobe, measure even, then have another look in a couple thousand km to compare. Removing the camshaft to get a look at the lobes might also be advisable if you have time and not in a rush. 

Hi Antares, thank you for such quick input.
I took a couple more photos and did a video. I inspected all lobes and found no noticeable lip, including the lobe in question.

I'll have a 4 day weekend starting tomorrow, so time isn't really an issue. I just lack the BMW tools to set the timing back after inspection. I've read here somewhere that there's an alternative method: using a metal ruller and a screw driver. I believe I understand how this would work for the side A of the BMW tool (0º timing). But considering this chain is no longer new, wouldn't the side B (1,7/1,6º) be more appropriate?

[Antares]

Originally Posted by jpdopaco

Hi Antares, thank you for such quick input.
I took a couple more photos and did a video. I inspected all lobes and found no noticeable lip, including the lobe in question.

I'll have a 4 day weekend starting tomorrow, so time isn't really an issue. I just lack the BMW tools to set the timing back after inspection. I've read here somewhere that there's an alternative method: using a metal ruller and a screw driver. I believe I understand how this would work for the side A of the BMW tool (0º timing). But considering this chain is no longer new, wouldn't the side B (1,7/1,6º) be more appropriate?

If you didn't unbolt the gears from the camshaft there is no need to touch timing, otherwise it's very simple. The left hand side of the engine at the end of the camshaft, there is 2 flats. When you have the cam gear marks lined up the other side of the shafts (the flats) should be completely flat and parallel. Make sure you can lay a metal ruler's edge across both shaft's flats and there is no gap anywhere, that's in time. FYI it doesn't need to be dead accurate, do your best, but mine was out a fair bit and the engine was still running perfectly fine, there isn't a lot of adjustment either way just what the bolt holes in the cam gears allow for.

[jpdopaco]

I'll look into it tomorrow. Thank you again for helping.

[Salish1000]

Hmmm. I'm not quite the XR internals expert that some others here are, but if I am understanding what you are saying, and the clearances are all in spec, then nothing about the surface of those cams should matter unless they were seriously out of round. If smooth everywhere and in spec, I don't think your clicking is from your cams. I don't think you mentioned your cam chain tensioner? I'd look there or somewhere else. Is your power unfaffected? Gas mileage?

Good luck, I'l follow this with interest.

[jpdopaco]

Originally Posted by Salish1000

Hmmm. I'm not quite the XR internals expert that some others here are, but if I am understanding what you are saying, and the clearances are all in spec, then nothing about the surface of those cams should matter unless they were seriously out of round. If smooth everywhere and in spec, I don't think your clicking is from your cams. I don't think you mentioned your cam chain tensioner? I'd look there or somewhere else. Is your power unfaffected? Gas mileage?

Good luck, I'l follow this with interest.

Exactly. Every valve is within spec - or maybe I didn't measure it properly - I used a feeler gauge and kept increasing until it didn't fit. Measured each lobe twice with the same results.
Exhaust cams were       |0.30\0.30| |0.30\0.28| |0.28\0.28| |0.29\0.28|

Intake cams were         |0,20\0,20| |0.18\0.20| |0.18\0.18| |0.18\0.16|

                                          (units in mm from cylinders 1 to 4)

Since I noticed the ticking noise was coming from the engine, I stopped riding and went straight home slowly. Couldn't tell if the mileage or power are affected.

I don't know how the tensioner could be at fault, but either way, I have a manual tensioner getting delivered soon.

[Antares]

Originally Posted by jpdopaco

Exactly. Every valve is within spec - or maybe I didn't measure it properly - I used a feeler gauge and kept increasing until it didn't fit. Measured each lobe twice with the same results.
Exhaust cams were       |0.30\0.30| |0.30\0.28| |0.28\0.28| |0.29\0.28|

Intake cams were         |0,20\0,20| |0.18\0.20| |0.18\0.18| |0.18\0.16|

                                          (units in mm from cylinders 1 to 4)

Since I noticed the ticking noise was coming from the engine, I stopped riding and went straight home slowly. Couldn't tell if the mileage or power are affected.

I don't know how the tensioner could be at fault, but either way, I have a manual tensioner getting delivered soon.

The hydraulic ones can gunk up, or the chain guides (not the chain) wear down enough so that there is no longer sufficient tension provided by the tensioner. You did say a fresh kit was installed though, I assume that includes the guides? Did you check other parts of the engine notably clutch or the lower timing gears?

Also, might sound stupid but it's caught more than a few people with their pants down in this forum: Check your mirrors. The glass can come loose and make a horrible racket, i thought my engine blew up when mine came loose. Alternatively a good look around fairings and ancillaries is also a good idea, tapping the bike around listening for buzzing or tapping noises.

[jpdopaco]

Originally Posted by Antares

The hydraulic ones can gunk up, or the chain guides (not the chain) wear down enough so that there is no longer sufficient tension provided by the tensioner. You did say a fresh kit was installed though, I assume that includes the guides? Did you check other parts of the engine notably clutch or the lower timing gears?

Also, might sound stupid but it's caught more than a few people with their pants down in this forum: Check your mirrors. The glass can come loose and make a horrible racket, i thought my engine blew up when mine came loose. Alternatively a good look around fairings and ancillaries is also a good idea, tapping the bike around listening for buzzing or tapping noises.

I haven't removed any other cover. I believe both the clutch and timing covers require new screws to be installed after disassembling and I don't have them. I peeked at the lower timing gears through the black cap when I was rotating the engine and didn't notice anything unusual. I'll try to examine if the noise is coming from the clutch.

I had someone say the cams looked like they weren't getting enough oil, perhaps a passage was blocked or the oil pump is weak.

[Antares]

Originally Posted by jpdopaco

I haven't removed any other cover. I believe both the clutch and timing covers require new screws to be installed after disassembling and I don't have them. I peeked at the lower timing gears through the black cap when I was rotating the engine and didn't notice anything unusual. I'll try to examine if the noise is coming from the clutch.

I had someone say the cams looked like they weren't getting enough oil, perhaps a passage was blocked or the oil pump is weak.

Can be worth exploring, re bolts for the covers, whilst it's not untrue, it's not strictly true either. They do stretch a bit and it's VERY easy to snap them off even when going back up to the specified torque, that said if you're careful you shouldn't need to replace them. A good idea to get a full set of stainless bolts thought if you get the chance and just replace the lot, it's what I've done for my clutch cover.