Any wisdom on KTM 790/890 Cam wear problems?

[jeff78]

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.

Yeah, the first time I saw a video of the inside of a KTM 790/890 head and saw those tiny little oil jets that are not an insignificant distance away from the followers, the first thing I thought was

The Japanese Big 4 all have 200hp production bikes that run finger follower valvetrains and they're not experiencing similar failures, at least not at this scale. But none of them lubricate the followers the way KTM does it.

For example, the Yamaha R1 has used finger followers for about a decade now. The followers are fed oil the same way the cam bearings are - from oil in the cam. There are holes drilled in the base circle of every lobe, and these holes are large, the same size as the holes in the cam journals, maybe a good 3-4mm in diameter. Plenty of oil everywhere at all times. These bikes may snap cranks, but their cams always look great.

I think these failures are not the result of just any one thing, but multiple possible contributing factors and when they all line up 'right' (wrong), your cam goes sayonara. The 'Swiss cheese model' as others have alluded to.

Poorly aligned oil passages during manufacture, low oil pressure/flow in certain conditions, debris blocking oil jets, shooting oil at the followers from a mile away instead of from nearby, etc.

 

[ktmDuke890r]

The mechanic who replaced the oil pressure relief spring with a part from the RC8C said that the left CAM was the most worn if there was any wear occurring. Due to the left CAM being at the end of the oil flow path. He didn't like the design either.

Good discussion.

 

[maraakate]

Not just this engine, many engines have had similar problems.I had a brand new Honda VF1100C (V65 Magna) that did this, it comes from improper break in by the dealer, by the time the customer got the machine it was too late. The fix was replace the cams and slippers, lube them well with a break in lube and run it at 2500 rpm for 20 min then change the oil. Using a higher zinc oil or zinc additive helps, at 100K the cams were still like new.

Uhh... have you seen this from someone who dealt with the warranty calls on these and also worked as a mechanic in the dealerships for many years? https://www.motorcycleproject.com/text/v4_page.html

Those V4s had issues with those cams and it wasn't from oil.

 

[Marrk]

Not just this engine, many engines have had similar problems.I had a brand new Honda VF1100C (V65 Magna) that did this, it comes from improper break in by the dealer, by the time the customer got the machine it was too late. The fix was replace the cams and slippers, lube them well with a break in lube and run it at 2500 rpm for 20 min then change the oil. Using a higher zinc oil or zinc additive helps, at 100K the cams were still like new.

I had a first generation VF700F. I worked at a dealership. Since when do dealers "break in" motorcycle engines, properly or improperly?

 

[dubber09]

My understanding is KTM engines shed metal throughout their entire life at much greater rate than most other engines. I saw a video awhile back with comparisons and they didn't look very good.

 

[KrisZ]

I had a first generation VF700F. I worked at a dealership. Since when do dealers "break in" motorcycle engines, properly or improperly?

By starting and running the engine as part of the vehicle pre-deliver prep. It doesn’t need to be a specific break in procedure to affect engine break in.

 

[Marrk]

By starting and running the engine as part of the vehicle pre-deliver prep. It doesn’t need to be a specific break in procedure to affect engine break in.

What is the proper way to sell a motorcycle? Take us through the steps from the time the motorcycle arrives at the dealership in a crate.

 

[ZeeOSix]

By starting and running the engine as part of the vehicle pre-deliver prep. It doesn’t need to be a specific break in procedure to affect engine break in.

Just firing up the engine after setup at the dealership isn't going to ruin a break-in. All those bikes are fired up and ran at the factory. Some engines are also rotated on a test standard to do an initial engine health check. So the engines have ran way before they are sent to the dealership. You can see this in many videos showing how motorcycles are manufactured.

 

[KrisZ]

Just firing up the engine after setup at the dealership isn't going to ruin a break-in. All those bikes are fired up and ran at the factory. Some engines are also rotated on a test standard to do an initial engine health check. So the engines have ran way before they are sent to the dealership. You can see this in many videos showing how motorcycles are manufactured.

Yes, but that wasn't enough to break in Honda VF1100C (V65 Magna) cam, which is what Trav was referring to.

 

[Marrk]

Yes, but that wasn't enough to break in Honda VF1100C (V65 Magna) cam, which is what Trav was referring to.

I can't find his post, but his link said it was a metallurgy issue on the cam followers. New bikes arrive at dealerships in crates. New cars arrive at dealerships on trucks and are driven off the trucks and onto the lot. Unless a great deal has changed since I worked in the industry.

 

[ZeeOSix]

Yes, but that wasn't enough to break in Honda VF1100C (V65 Magna) cam, which is what Trav was referring to.

The root cause of the issue wasn't caused by how the engine was broken in. If it was, Honda would have figured that out way before anyone else. Honda had a hard time themselves tracking down the root cause, as seen by how the issue unfolded with special tools to adjust the valves and changes made to the heads.

 

[donnyj08]

Here’s my Take as an Owner of a 790 Adventure. Granted my bike is a 2024 and is built by CF Moto so I supposedly have a “fixed” bike.

1. The original 790 engines had very narrow finger followers (like 6mm) riding on a 10mm wide lobe. The updated versions are 8mm or so.

2. The Cam lobes on the 790/890/901s are a super aggressive profile.

3. The oil jet design works, but it’s probably not as reliable as a traditional oiling system as it relies on pressure/velocity at the nozzle. What this means is that they are susceptible to clogging with debris. KTM added a filter screen in the head in 2021 to prevent debris from getting into the jets. Oil jets in a shared sump system where clutch debris and potential gear wear debris can clog tiny holes is a problem IMO. The screen is kinda a bandaid, but it does keep debris out of the jets. I believe most early 2019-2021 failures were due to clogged or restricted oil jets and misaligned oil passages combined with narrow finger followers

4. Warm up time is essential. Anytime you have a DOHC engine with finger followers letting the engine warm up a couple of minutes before riding is key IMO. You want heat to develop in the oil before RPMs get high so that if film strength is diminished the ZDDP in the oil is active.

5. Use shear stable oil. 10w50 as recommended by KTM is not shear stable for a normal interval, and certainly not for 9300 miles as they claim. Within 1k miles the oil has sheared into a 30wt. This is insufficient for aggressive cam lobes running on finger followers. 15w50 or 20w50 with a stout additive package and 2-3k mile intervals MAX is best practice, along with a proper warmup time. Don't rev or beat on the engine until the oil is up to temperature. I literally do not get above 4K RPM for at least 10-15 minutes of ride time.

I also don’t buy into the rev it high theory to keep oil on the cams. Higher RPMs equal more heat and more wear especially at low riding speeds. The engines are able to get oil onto the lobe with just the starter cranking, there is plenty getting there at 1500-1700 RPM idle. There isn’t a need to hold them at 5K RPM or higher constantly as some believe. The engine makes phenomenal power at 3K RPM and it gets enough oil if the gallies are aligned correctly and the jets are clear.

I honestly think the problem is “mostly” solved with the latest iterations. That doesn’t mean that the engine will last as long as many would hope, and I think that is mostly due to the Cam lobe profile and the engine design. With lobes that aggressive I believe some “normal” for the engine design wear will be expected at high mileages. I don’t think anyone is getting 100K miles and 0 cam wear out of an LC8c.

I’ll attach a photo of my Cams at 20,735 miles. They look pretty good, and valves were in spec both times they were checked. They were checked at 12,795 miles and 20,735 miles.

I do believe CF Moto has resolved the major issues and assuming proper maintenance and warmup time I think the majority of the 2023 and later LC8c engines will live far longer than most will keep their bikes.

I’ve had Yamahas and Kawasakis before buying my 24’ 790 and I can Honestly say the 790 has been just as reliable as the other 2 so far.

I wouldn’t buy an early generation bike, but I certainly would buy another new 790/890 or a Norden 901, especially with how affordable you can buy a leftover Norden 901 right now.


I can confidently say with proper maintenance and care a newer 790/890/901 can provide 20k+ miles of fun and still run perfectly with good cams and valves that are in spec. I see no reason why I can’t get 50-60k miles out if the bike. By then I think one has gotten their moneys worth. It was only $10,900 New!