Any wisdom on KTM 790/890 Cam wear problems?

[ktmDuke890r]

A few details we don't know is whether the spring rates used are progressive or linear.

We also don't know if the relief valve is designed to function as a key component of realtime continuous pressure regulation.

A spring component designed to regulate pressure from idle would explain an idle pressure change occurring after a replacement.

Some more maybes. What if this pump is used across different engine varients with different oiling conditions and requirements? If a spring change is all that is required production efficiencies are achieved.

But maybe Euro 5 comes along and says no, this varient won't pass an emissions spec unless oil is reduced.

Given that a spring change alters idle pressure and KTM have never upgraded the spring in the model years subsequent to the failures (that we know of) and that the low spring rate is the cause of the pressure failure, Euro 5 compliance is the only explanation I can reason about without material evidence.

Given EU politics moving rapidly towards ideological instruments, and the rise of bureaucratic ignorance towards the effects of regulatory stress (occurring due to increasingly suppressive compliance enforcement) the current and future Euro emissions schemes appear to be responsible for an increasing number of problems for businesses fully invested in internal combustion engine technology.

If Euro 5 is responsible for the spring selection there is no way KTM (or any other company) could publically say anything about it.

What we know — the Western free market world is under the heaviest bureaucratic regulatory stress in its relatively short history and it is getting worse. Only Soviet Russia and China implemented a more extreme regulatory regime, and China is currently ahead of the West in implementing this ESG style Stakeholder Capitalism.

However, China isn't suffering from an energy crisis brought on by ideological politics. They can't build power coal, hydro, nuclear, natural gas and solar electricity generation fast enough.

Many large corporations are happy to help push compliance, especially tech giants, but others are suffering from it and ultimately there will need to be pushback or they will cease to exist.

 

[KrisZ]

But maybe Euro 5 comes along and says no, this varient won't pass an emissions spec unless oil is reduced.

Nope, they are literally too stupid and incompetent to even know what oil does to emissions, or what an oil pressure regulator is.
As much as I hate what the emission regulation has become, they are not responsible for any design flaws, they just set the pollutant limits. They absolutely do not in any way intervene with any of the design when it relates to emissions.

The final product simply has to pass the emissions, that's all they care about.

If manufacturers were really so bothered about meeting emissions, they would've put out a campaign explaining how every iteration of Euro mission standard has impacted the customer's pocketbook. They will not do that because they have a very convenient scapegoat to blame in case they screw up. Plus they get to charnge more for their product.

 

[ktmDuke890r]

I agree that the EU ETS would not have got involved in designing the implementation. This choice would have been up to KTM. Maybe their decision, if this were the case, took them dangerously close to minimums and in some conditions caused failure? They can't admit they are struggling to meet EU ETS.

This is all speculation but I can't find a good reason why KTM would not upgrade the spring in later year models subsequent to the problem manifesting — presuming that the spring fix is indeed valid and correct.

There is growing material evidence that validates the oil pressure thesis. Validation of the spring fix is a matter of time.

 

[ZeeOSix]

Yeah, how an oiling system is designed doesn't impact exhaust emissions. Emissions are controlled by the combustion process in the cylinders via efficient ECU control and the catalytic converter on the exhaust gasses. It may impact fuel economy with the slightest degree if the pump is over sized and wasting a bit of the engine's power and fuel pumping more oil to the engine than it really needs too. Are motorcycles in the EU required to get some minimum target fuel mileage? If not, then the design of the oiling system isn't going to be focused on saving fuel. It should be designed to provide well over the minimum required oil flow volume to keep moving parts happy and safe from wear and damage.

This issue has to be an oiling issue ... lack of oil volume to required moving parts is detrimental. By increasing the pump output pressure with a different relief spring, that results in more oil volume flowing throughout the oiling system. Like mentioned before, since not all KTMs experience this issue, it could be an issue with the manufacturing process where certain oil supply galleries to and in the head are not manufactured correctly and cause undue restriction and choke down the oil supply to the valve train. In a case like that, increasing the oil supply pressure (ie, changing the relief spring) will also result in more oil volume, even if the flow path to the valve train is restricted from manufacturing flaws.

 

[KrisZ]

To me it’s a design issue at its core. Increasing oil supply by charging the relief valve spring is just a band aid fix.
Personally I have not seen cam lobes being lubricated by oil jets positioned so far away. Perhaps this is racing engine tech, but it clearly doesn’t work well in normal, everyday use.

Lazy engineering, poor manufacturing and in general being cheap. That’s seems to be the theme in this case IMO.

 

[ZeeOSix]

To me it’s a design issue at its core. Increasing oil supply by charging the relief valve spring is just a band aid fix.

Seems like there would be way more of these KTMs eating cams and followers if it was purely a design issue. If you believe KTM's claim (pointed out in the YouTube video earlier in this thread) that it has shown up in 0.5% of the bikes, then it seems to point more to a manufacturing QA issue. Or it's a design that shows a weakness only under certain rare operating conditions.

Personally I have not seen cam lobes being lubricated by oil jets positioned so far away. Perhaps this is racing engine tech, but it clearly doesn’t work well in normal, everyday use.

As mentioned before, I'd like to see those oil jets in the YouTube video that lubricate the cams operating at idle and at higher RPM - not just cranking over the engine with the starter motor. As the YouTube guy pointed out, if the RPM is low for extended periods it could be that results in a lack of lubrication on the cam lobes and followers. He mentioned that the people who ride harder at higher RPM don't seem to have the problem because higher RPM would give more oil flow to the valve train.

Yes, trying to increase the oil flow volume by using a stiffer pump relief spring is a "band-aid" fix, but if that modification increases the oil flow enough to fix the issue then it's still a win, and a pretty simple fix to boot.

 

[ktmDuke890r]

I doubt very much that the LC8c engine has serious design flaws. KTM rolled out the RC8C race bike for 2024 using the LC8c. The RC8C uses the higher rated spring part that was ordered and placed into my Duke's version.

Why would the RC8C be allowed a higher rated spring which flows more oil into the engine and a higher ratio burnt into exhaust emissions? Because it is a very limited production race bike compared to the wildly popular 790/890 Dukes and Adventure bikes.

https://www.ktm.com/en-int/models/supersport/2024-ktm-rc-8c.html

 

[Nessism1]

I doubt very much that the LC8c engine has serious design flaws. KTM rolled out the RC8C race bike for 2024 using the LC8c. The RC8C uses the higher rated spring part that was ordered and placed into my Duke's version.

Why would the RC8C be allowed a higher rated spring which flows more oil into the engine and a higher ratio burnt into exhaust emissions? Because it is a very limited production race bike compared to the wildly popular 790/890 Dukes and Adventure bikes.

https://www.ktm.com/en-int/models/supersport/2024-ktm-rc-8c.html

If it's not a design flaw, what is causing all the cams to fail?

 

[ZeeOSix]

If it's not a design flaw, what is causing all the cams to fail?

Mostly likely a manufacturing issue. Like said before, if the root cause was an actual "design flaw" there would be way more than the claimed 0.5% per KTM failing. If there is any possible design issue factor, then it takes some rare kind of use conditions (the "Swiss cheese model" of failure talked about in the YT video) to make the problem show up since not all the bikes exhibit the problem. You can have the best specs and drawings known to mankind, but if the parts made per those perfect drawings and specs can't be successfully manufactured then there could be problems as a result. This is why in industry there are design engineers and there are manufacturing engineers. Manufacturing engineers figure out how to successfully manufacture the design made by the design engineers.

 

[Nessism1]

Mostly likely a manufacturing issue. Like said before, if the root cause was an actual "design flaw" there would be way more than the claimed 0.5% per KTM failing. If there is any possible design issue factor, then it takes some rare kind of use conditions (the "Swiss cheese model" of failure talked about in the YT video) to make the problem show up since not all the bikes exhibit the problem. You can have the best specs and drawings known to mankind, but if the parts made per those perfect drawings and specs can't be successfully manufactured then there could be problems as a result. This is why in industry there are design engineers and there are manufacturing engineers. Manufacturing engineers figure out how to successfully manufacture the design made by the design engineers.

I'm manufacturing engineering manager at the aerospace component supplier that I work for. What kind of "manufacturing issue" are you placing blame on? Keep in mind, the cam failure issues have spanned a good many years.

KTM is full of crap with their .5% claim. There wouldn't be a facebook page with 11,000 member if that was the case.

 

[Bottom_Feeder]

Has the aftermarket come up with any solutions to this? Not that the owners should have to pay for it of course, but I would assume if it's fixable then there would be enthusiasts out there who would be more than happy to pay to have their motors fixed and even upgraded if a solution was found. Car guys love to have a reason to do that.

 

[ZeeOSix]

I'm manufacturing engineering manager at the aerospace component supplier that I work for. What kind of "manufacturing issue" are you placing blame on? Keep in mind, the cam failure issues have spanned a good many years.

Cam and follower material quality, cam and follower case hardening and/or coating quality, casting and machining of oil galleries in the head that effects supplied oil volume to the cam and followers. Even sloppy dirty manufacturing could leave debris in the oiling gallery system and choke oil flow. Could be a combination of more than one factor adding up in the wrong direction (Swiss cheese failure model). If there is a major choke point in the oil supply gallery system, it's going to result in inadequate oil supply volume and lubrication to critical parts. Could also stem from poor oil pump performance (again, lack of adequate oil volume) for some reason related to the manufacturing of the pump. If the relief spring is the actual root cause, and KTM says to put in a different spring to keep the pump out of relief at lower RPM and therefor supply more oil volume at lower RPM, then I'd categorize that as a "design problem", and KTM should have been smarter than that to allow that to actually happen.

Like said, you can have the best engineering design, drawings and specifications in the world, but if it can't be manufactured to the drawings and specs you're going to have possible problems. You should know that if you're a manufacturing engineering manager. If your manufacturing engineers can't manufacture the product to meet all the design drawings and specs, you've failed as a manufacturer.

If you think the root cause is an actual design flaw, exactly what is this supposed design flaw that only effects some of the bikes?

 

[ZeeOSix]

KTM is full of crap with their .5% claim. There wouldn't be a facebook page with 11,000 member if that was the case.

And all 11,000 of them have seen this failure?

 

[ktmDuke890r]

The mechanic who swapped the spring out on my Duke said that, in response to my question, none of the bikes bought to him to check had issues with their CAMs. I was one of those people. He said that the only bikes he has worked on that had CAM failure were identified as failed and brought to him to apply the spring fix after they were fixed under warranty by KTM. At least that was the implication as he said he was unable to process warranty claims.

I personally think the EU ETS is subjecting design and manufacturing to some real F***kery and compliance gymnastics for ideological motivations, especially for bikes which are relatively few and generate minimal pollution. It seems clear to me that the pressure relief design that KTM uses is interesting in that it appears to be used to directly accommodate engine variants. I think it is also likely one easy way to meet Euro 5 compliance and that it is possible that the CAM failures were considered low by KTM, were possibly occurring under some unique conditions, and it wasn't worth a compliance breach to change something as simple as a spring. Pure speculation but not an unreasonable one. We may never know. The other thing I accept is that my bike may never have needed the spring fix but I did it anyway.

Now my quest is to reduce the heat the oil is subject to in stop start traffic in my climate. I'm starting with the removal of that massive heatsink called the Catalytic Converter. The heatsoak into the lower engine is insane. In goes a link-pipe with a resonator.

I have been scratching my head over the fact that the headers and exhaust basically wrap the engine and do not have any engine-side insulation. Definitely won't be putting a belly pan on the bike.

 

[Nessism1]

Cam and follower material quality, cam and follower case hardening and/or coating quality, casting and machining of oil galleries in the head that effects supplied oil volume to the cam and followers. Even sloppy dirty manufacturing could leave debris in the oiling gallery system and choke oil flow. Could be a combination of more than one factor adding up in the wrong direction (Swiss cheese failure model). If there is a major choke point in the oil supply gallery system, it's going to result in inadequate oil supply volume and lubrication to critical parts. Could also stem from poor oil pump performance (again, lack of adequate oil volume) for some reason related to the manufacturing of the pump. If the relief spring is the actual root cause, and KTM says to put in a different spring to keep the pump out of relief at lower RPM and therefor supply more oil volume at lower RPM, then I'd categorize that as a "design problem", and KTM should have been smarter than that to allow that to actually happen.

Like said, you can have the best engineering design, drawings and specifications in the world, but if it can't be manufactured to the drawings and specs you're going to have possible problems. You should know that if you're a manufacturing engineering manager. If your manufacturing engineers can't manufacture the product to meet all the design drawings and specs, you've failed as a manufacturer.

If you think the root cause is an actual design flaw, exactly what is this supposed design flaw that only effects some of the bikes?

A "manufacturing issue" relates to poor quality. And to a manufacturing person, "quality" means "adherence to specifications".

It would be exceedingly unlikely for there to be hardness issues on the cams & followers, that lasts for several years. At the first wind of failing cams and rockers, the supplier quality guys would be testing hardness, and resolving that issue with the supplier.

Almost certainly, there are issues with low oil supply. The oil flow path is convoluted, leading to pressure loss as the oil flows through the galleys. KTM added restrictions, in the way of screens into the system also. it could be that the pump simply doesn't produce enough flow, or the relief is set too low, or what have you. Rocker arm valve trains have far more oiling issues, than shim and bucket. Personally, I don't like rocker arms on motorcycles. Shim and bucket is almost bulletproof.

 

[ZeeOSix]

A "manufacturing issue" relates to poor quality. And to a manufacturing person, "quality" means "adherence to specifications".

Saying the same thing. Bottom line is that if the drawings and specifications defined by engineering on every level to produce a product are not followed and successfully met by manufacturing, then there is a "manufacturing issue". If everything is manufactured within specs on every level, then it would point back to a "design issue" ... like an inadequate oil volume being supplied to all moving parts within the engine based on the actual design of the system, or even the wrong materials and/or heat treatment and coatings being specified by engineering.

It would be exceedingly unlikely for there to be hardness issues on the cams & followers, that lasts for several years. At the first wind of failing cams and rockers, the supplier quality guys would be testing hardness, and resolving that issue with the supplier.

You'd think if they had their stuff together. If the cam and followers test out as meeting specs, then it should point them to look for another cause, like lack of oil supply to the failing parts. Keep in mind that not all materials, heat treat & coatings are created equal on the final product, and if they are not on the more robust side of the scale then some lack of lubrication may make them fail pretty fast. Engine components like cams and followers are in boundary lubrication, and their materials, heat treat and/or coatings are critical to longevity, even with good lubrication.

Almost certainly, there are issues with low oil supply. The oil flow path is convoluted, leading to pressure loss as the oil flows through the galleys.

If this is the case, as I have said a few times already in this thread, it could be a manufacturing issue with the heads and their oil galleries because not every bike has this issue - they all don't eat cams and followers. Why do some eat cams and followers and the mass majority don't.

KTM added restrictions, in the way of screens into the system also.

Depends on how fine that screen is and how much flow area it has. It would surprise me if that screen filters finer than the full-flow oil filter before it. If it does filter down to say 10 microns (doubtful), then yes it could cause a dP and impact some flow to the head. As I mentioned before, if it can't filter better than the main filter then it seems like a useless filter.

I'd like to know if that screen is plugged up to some degree on the bikes that do eat their cams & followers. Could be it captures debris coming off something after the main filter (why else would it be there?), gets partially plugged and then cuts oil flow to the head.

it could be that the pump simply doesn't produce enough flow, or the relief is set too low, or what have you. Rocker arm valve trains have far more oiling issues, than shim and bucket. Personally, I don't like rocker arms on motorcycles. Shim and bucket is almost bulletproof.

Sounds like the PD oil pump is sized correctly, and if manufactured correctly should be able to put out more flow than the engine requires. Since we have a data point that the oil pressure at idle went up by putting a stiffer relief spring in the pump, then that indicates the pump is not under sized.

A shim and bucket valve train still needs adequate materials, heat treatment and oil supply volume to survive well. Lack of lubrication will pretty much end up destroying anything with time.

 

[OCD-OCI]

There is a thread somewhere on Advrider where one of the members showed that two oil galleys, made by a drill, didn't line up correctly Basically severely limiting the oil flow to one of the lobes. It looked like a easy manufacturing error,but was obviously the problem on the engine that he had photos of. I'm pretty sure that is the rot of all of the 790/890 motors. Shame, as the bike is perfect on so many levels.

 

[midobo]

There is a thread somewhere on Advrider where one of the members showed that two oil galleys, made by a drill, didn't line up correctly Basically severely limiting the oil flow to one of the lobes. It looked like a easy manufacturing error,but was obviously the problem on the engine that he had photos of. I'm pretty sure that is the rot of all of the 790/890 motors. Shame, as the bike is perfect on so many levels.

That post was severely flawed. Yes, the oil gallery and the oil jets supplies are offset slightly. But the jets have a .5mm orifice. There's still several square millimeters of surface area where the oil galleries meet up. There's no restriction there.
An analogy would be: Your front door is narrower than the hallway leading to the door. But you're only using the mail slot, so the size of the hallway doesn't matter.

 

[KrisZ]

That post was severely flawed. Yes, the oil gallery and the oil jets supplies are offset slightly. But the jets have a .5mm orifice. There's still several square millimeters of surface area where the oil galleries meet up. There's no restriction there.
An analogy would be: Your front door is narrower than the hallway leading to the door. But you're only using the mail slot, so the size of the hallway doesn't matter.

It actually does matter because there is one oil galley supplying all four jets in series. This means that the jet furthest from the pump gets the least amount of oil supply and may not have enough pressure to squirt the oil onto the camshaft. Think of a sprinkler system with too many sprinkler heads connected to one run. The last ones on the line won't spray as far as the rest.
Or think of a water hose when you can put your finger over the end to get the water to shoot out further. Now put a kink in the hose somewhere and try to put your finger on the end, the water will not shoot out as far because there is not enough flow.

That's how oil jets and squirters work, they need a certain oil volume to operate properly. Anything that limits that minimal volume will affect their operation negatively.

This could be mitigated by using different size jets for example, or higher oil pump volume. Like I mentioned before, this lubrication design is quite bad for street engines. It may work great for race engines, but it's a bad design for normal use, so it's not just possible manufacturing issues. A good design should account for manufacturing challenges associated with mass production.

 

[Nessism1]

Relying on a squirter is not the most robust design solution. Cars like the Mazda Skyactiv engines have an oil feed rail over top of the cam, that dribbles/sprays oil from on top. Even if pressure was poor, the cams would still get oil.

Regarding the "end of run" oil passage being subject to poor flow, that may be true, however, from the photos that I've seen of these engines eating cams, it's not just one particular location that gets damaged.