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790/890 Failed Cams

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#82 · (Edited)
Gear on the back of the clutch basket drives an intermediate gear (parts 48/11/12 in the diagram above, on its own bearing, mounted behind the clutch on the crankcase), which turns the oil pump gear.

Oil pressure, hot engine idling >20 psi
Oil pressure, hot engine 6krpm >35 psi.
Tested at the outside end of the oil filter with an adaptor plate 75029094000.

PS. How can I extend the warranty on my 890R?
 
#83 ·
bobdysart said:
Gear on the back of the clutch basket drives an intermediate gear (parts 48/11/12 in the diagram above, on its own bearing, mounted behind the clutch on the crankcase), which turns the oil pump gear.

Oil pressure, hot engine idling >20 psi
Oil pressure, hot engine 6krpm >35 psi.
Tested at the outside end of the oil filter with an adaptor plate 75029094000.

PS. How can I extend the warranty on my 890R?
Click to expand...
You tested? Bit low, I'd expect 50-60 psi at those revs.
 
#85 ·
Many thanks to those who posted video of the oil supply on running engines.

Obvious that the lubrication is sketchy as i have worked on push-rod engines where you cannot run them with the valve covers off or you get sprayed with oil lol.

Poor oil delivery does explain why most pictures appear to be of shagged left hand cams.

But to me it is more worrying than the poor hardening theory - because there are very few reasons why an engine cannot deliver the designed oil flow.

It seems that it could only be a restriction in that particular oil distribution branch or poor pump design/manufacture.

If it was the latter there would be tales of crank failure on some engines so it looks like it is a restriction in the oil feed to the cams. But is that designed in or repairable and is it casting? Head gasket? barrel gasket? or what?
 
#86 ·
lcjohnny said:
Obvious that the lubrication is sketchy as i have worked on push-rod engines where you cannot run them with the valve covers off or you get sprayed with oil lol.
Click to expand...
Yeah, this. From what's been posted on the Facebook group it looks like poor oiling to me. Not enough pressure or splash. KTM are just masking the root cause with cam replacement.

Nothing about WP seals or dodgy cams. Just no oil at low revs. I'd love to see oil splash at mid revs.
 
#91 ·
Interestingly (or not), I’ve just spoken to the service dept at Premier Bikes. My Duke 890R has got to go in for an annual service - the last one before the warranty runs out. The bike is a little rattly but goes very well indeed. The service manager there said that they’ve not had any cam issues with Duke 890Rs - the only ones they’ve seen have been with 790s, and then generally on Adventures. Also he told me that it isn’t possible to extend warranties, but they will have a good look over my bike when I take it in. So fingers crossed eh?
 
#92 ·
TrouserSnake said:
Nah, I don't buy it.
Even if it works it's just masking the problem. The oil flow on a healthy engine/head looks good so increased oil pump pressure isn't required and might even cause problems later on for good engines.
Click to expand...
Its not increasing oil pump pressure, just at what point the valve dumps excess pressurised oil back into the sump.
 
#93 · (Edited)
charlie264 said:
Its not increasing oil pump pressure, just at what point the valve dumps excess pressurised oil back into the sump.
Click to expand...
The valve acts as a pressure regulator.
Increasing the spring tension is increasing the max running pressure of the pump, which will most likely happen when the oil is cool and also when the engine is at higher rpm, if the pump is even capable of supplying the higher pressure.

If so then there could be many reasons why the max pressure of a pump was set lower. Raising the max could cause damage or unintended effects to other parts of the engine that are exposed to this higher pressure.
It most likely won't but I wouldn't be doing that unless someone that knows the engine design (like KTM) has looked at this mod to see if there's any implications to the rest of the engine or the pump.
 
#94 · (Edited)
TrouserSnake said:
The valve acts as a pressure regulator.
Increasing the spring tension is increasing the max running pressure of the pump, which will most likely happen when the oil is cool and also when the engine is at higher rpm, if the pump is even capable of supplying the higher pressure.

If so then there could be many reasons why the max pressure of a pump was set lower. Raising the max could cause damage or unintended effects to other parts of the engine that are exposed to this higher pressure.
It most likely won't but I wouldn't be doing that unless someone that knows the engine design (like KTM) has looked at this mod to see if there any implications to the rest of the engine or the pump.
Click to expand...
Oil pressure is critical at higher revs, at 6000rpm I'd expect to see 50psi. Oil pressure needs to rise linier with rpm, a race engine at 16000rpm you'd expect to see >130psi, run it at 50 psi and the crank bearing would weld themselves to the crank, its the oil forced under pressure that stops the metal on metal contact.

My experience with KTM dealers, its always the first incidence they've ever seen. KTM (UK) can he proves us wrong.
 
#95 ·
charlie264 said:
Oil pressure is critical at higher revs, at 6000rpm I'd expect to see 50psi. Oil pressure needs to rise linier with rpm, a race engine at 16000rpm you'd expect to see >130psi, run it at 50 psi and the crank bearing would weld themselves to the crank, its the oil forced under pressure that stop the metal on metal contact.
Click to expand...
I'm not really sure what point you're making.

KTM have decided what the max pressure should be and so have a designed in a limiter on the oil pump (a bypass regulator factory set to the max pressure allowed).

Modding this limiter to increase the limit doesn't make any sense for this suspected fault. The issue appears to be lower than expected oil pressure on some engines at low or all engine speeds. Adjusting the limiter isn't going to do anything if the problem is only at low engine speed, or because of a weak or damaged oil pump. Likewise a blocked jet probably isn't going to unblock just because the pump is allowed to run at a higher pressure when the revs get high enough.
 
#96 ·
TrouserSnake said:
I'm not really sure what point you're making.

KTM have decided what the max pressure should be and so have a designed in a limiter on the oil pump (a bypass regulator factory set to the max pressure allowed).

Modding this limiter to increase the limit doesn't make any sense for this suspected fault. The issue appears to be lower than expected oil pressure on some engines at low or all engine speeds. Adjusting the limiter isn't going to do anything if the problem is only at low engine speed, or because of a weak or damaged oil pump. Likewise a blocked jet probably isn't going to unblock just because the pump is allowed to run at a higher pressure when the revs get high enough.
Click to expand...
From reading and seeing what damage has occurred, my point is I suspect its too low oil pressure at higher rpms. KTM probably reduced the oil pressure for this engine to meet emissions targets, engines that are designed to run at lower oil pressures tend to have tighter tolerances so those accumulative effects help maintain oil pressure throughout the engine, ie no leaky gaps.

Looking at the workshop manual, its a simple engine.
 
#97 ·
charlie264 said:
From reading and seeing what damage has occurred, my point is I suspect its too low oil pressure at higher rpms
Click to expand...
Ok, but I think it's too early to make that assumption, and certainly too early to start making oil pressure limiter mods.

All I've seen regarding oil flow is that some engines produce a good jet of oil to the cams when cranking while others don't.
I'm not sure how that correlates to the ones with worn cams, maybe it doesn't and all of them can still produce a good enough jet at idle.
Maybe the cam wear isn't oil related at all.
 
#98 ·
TrouserSnake said:
Ok, but I think it's too early to make that assumption, and certainly too early to start making oil pressure limiter mods.

All I've seen regarding oil flow is that some engines produce a good jet of oil to the cams when cranking while others don't.
I'm not sure how that correlates to the ones with worn cams, maybe it doesn't and all of them can still produce a good enough jet at idle.
Maybe the cam wear isn't oil related at all.
Click to expand...
Maybe, remember the oils function also is to remove heat from parts, even say a 10psi drop could result in half the volume of oil removing heat from the cams. I guess the video of the guy with a 2.5k bill winds me up.

For all I know the drain oil-ways could be too small for higher pressure and the kiln not getting hot enough at the ends to harden the end lobes properly....who knows. To me the engine doesn't look like it was built to last, but without stripping one its all gut feeling.
 
#100 ·
bobdysart said:
Interestingly (or not), I’ve just spoken to the service dept at Premier Bikes. My Duke 890R has got to go in for an annual service - the last one before the warranty runs out. The bike is a little rattly but goes very well indeed. The service manager there said that they’ve not had any cam issues with Duke 890Rs - the only ones they’ve seen have been with 790s, and then generally on Adventures. Also he told me that it isn’t possible to extend warranties, but they will have a good look over my bike when I take it in. So fingers crossed eh?
Click to expand...
Not extend the warranty ?
Past the initial period ?
It’s 2024 - you can buy extra years warranty with every car and bike manufacturer-what planet are KTM on ?
 
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