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Improved reliability with direct oil feed to head ?

Tom

Tom

Joined Aug 2005
14 Posts | 0+
Melbourne Australia
Do you think the bergs reliability would be improved if the cylinder head were forced oil feed in addition to just relying on the cam chain's lubrication ?

I noticed on the highland engine, which looks similar to the berg, that the head has an oil feed.

Tom
 
Surely do, and dont know just how much benefit it is- all rocker shafts I have seen out of 02/03 bikes have much more wear than you would expect from a pressure fed rocker arm.

Maybe more advantageous in the pressure fed top end is the spray holes in rockers for valve stems etc.

I do not like the pressure feed design- both rocker shafts share the same size orifice even though it passes through 1 shaft on its way to the next.
I would have thought the rocker shaft that is fed first would have had a larger lube hole to ensure no pressure drop to the 2nd rocker shaft.
But then again, restriction should be taking place at the rocker spray holes, not at the rocker shafts if oil gallery areas have been calculated correctly by engineers

But I'm not an engineer, so I dont really know about such things :)

Earlier and later ,Bergs and KTM RFSs seem to do just fine without a pressure fed valve train, ( even though the RFS has an oil line to head it is a simple dump system onto cam lobes)-.
 
LINEAWEAVER said:
Hi Tom,
2001 through I believe 2003 Husaberg engines do pressure feed the top end.

Dale
Click to expand...

I wonder what prompted its deletion in later years??
 
My 2 cents is that it just does not lubricate well enough to justify it (01-03 break just the same) plus is a pain when you do a rocker cover job. Easy to lose the teeny-tiny o-ring. :roll:
 
My own personal belief is that Husaberg did away with the pressurised head oiling to try and maximise flow to crankshaft/spray jet.

As Huasberg had previously utilised a splash/mist lubrication design on their earlier bikes with minimal wear related faults, going to the pressure fed rocker gear was a fix for a problem that did not exist.

With the pressure fed rocker gear of the 02/03 bikes, any excessive wear of the rocker bushings/shafts results in an overall system pressure/flow drop, and even just utilising this oil to pressure feed to the rockers does the same.

As they had experienced some crankpin/ mains and piston related issues I believe the pressurised flow to the rockers was deleted to maximise the flow to the bottom end as I mentioned above.

But as I mentioned in the previous post of mine, I'm no engineer :)
 
I can certainly tell you that the pressure-oiled head of ´02 gets quite some wear. I replaced both shafts for the rocker arms at ~150 hrs.
I am now going LXR-2 cam and softer dual springs to help the overall life-span of the valve-train. Not primarily for power gain.

As for the reason not to keep the pressure line:

1. The ´04 and later camchain tensioner arm uses that area for it´s longer pivot shaft. I know, because I had to shorten the shaft to fit the newer tensioner arm to my ´02.

2. Any unnecessary machining costs money in production. If it doesn´t do any good - get rid of it. Drilling deep, narrow holes is quite time-consuming and expensive actually (plus it´s one more set-up, one more tool).

Knowing this, I am pondering plugging the pressure line to the head and divert all pressure to the crank shaft and the con-rod big end. That should also lead to more splash onto the piston and main bearings.
A good thing I would think. But it could be that full pressure is already being applied there, and all surplus will just be dumped by the releif valve.
There, I just talked myself into not doing it... but that frickin´ tiny o-ring...

/Peter
 
AUSBERG said:
Surely do, and dont know just how much benefit it is- all rocker shafts I have seen out of 02/03 bikes have much more wear than you would expect from a pressure fed rocker arm.
Click to expand...

My '03 is pressure fed, but I found sealant in the oil passage, which effectly nullified most of the flow and benefit.

Check your passages when disassembled and be careful not to get sealer in the hole upon reassembly.

As Lineaweaver has mentioned in the past, the durability is adversely affected by the profile of the cam.
 
Splat said:
My '03 is pressure fed, but I found sealant in the oil passage, which effectly nullified most of the flow and benefit.

Check your passages when disassembled and be careful not to get sealer in the hole upon reassembly.
Click to expand...

Very true. Previous owner did not consider this at all. Not that I think it matters considering the current production has no oil line whatsoever.

I just wish to say that using Hermetite yellow (which is a soft sealant, not a silicone), you can apply an extremely thin layer without worries about it drying on you. The "working time" is very long, in fact it can be dry when you slap the pieces together. The seal is perfect and the mess minimal. The oil passage stays clear. The thing to look out for here is that if you apply too much of this sealant, the excess WILL end up in your oil screen... I Know... So use the bare minimum.
 
Aspen said:
I can certainly tell you that the pressure-oiled head of ´02 gets quite some wear. I replaced both shafts for the rocker arms at ~150 hrs.
I am now going LXR-2 cam and softer dual springs to help the overall life-span of the valve-train. Not primarily for power gain.

As for the reason not to keep the pressure line:

1. The ´04 and later camchain tensioner arm uses that area for it´s longer pivot shaft. I know, because I had to shorten the shaft to fit the newer tensioner arm to my ´02.

2. Any unnecessary machining costs money in production. If it doesn´t do any good - get rid of it. Drilling deep, narrow holes is quite time-consuming and expensive actually (plus it´s one more set-up, one more tool).

Knowing this, I am pondering plugging the pressure line to the head and divert all pressure to the crank shaft and the con-rod big end. That should also lead to more splash onto the piston and main bearings.
A good thing I would think. But it could be that full pressure is already being applied there, and all surplus will just be dumped by the releif valve.
There, I just talked myself into not doing it... but that frickin´ tiny o-ring...

/Peter
Click to expand...

Peter,

If you plug the pressure line to the head, make sure you drill splash/drip oil feed holes in the rocker arms.

Joe
 
JoeUSA said:
If you plug the pressure line to the head, make sure you drill splash/drip oil feed holes in the rocker arms.
Click to expand...

Good point! I remember reading a thread about this. Not too long ago.
I do remember being a little confused about this, since my arms, both the ´02 and revised ´03 arms do have small holes drilled. They are however jets aimed at the valves. The correct size and position of these splash/drip-holes I would really like to know.

And with this in mind, it would in fact really matter if the oil line gets plugged with silicone.
Thanks Joe for pointing this out!
Hey, look at my signature and Ya Know Im Grateful!!! :D
 
Gentlemen,
The oil pump is of a fixed displacement.
Post 2003 engines spray oil directly to the balancer as opposed to wasting it on the top end.

Now what do you think of that Tomahawk spinning between your legs? :lol:

Best Regards,
Dale
 
LINEAWEAVER said:
Now what do you think of that Tomahawk spinning between your legs? :lol:
Click to expand...

One more use for that big large central beam I guess.

As Splat says, you have to be careful not to put too much sealant in that area. Better be on the safe side.

And changing the oil more often, even if it ends up being somewhat costly and non-environmental can end up saving you a lot of money down the road (or trail).
 

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