I'm no expert on this subject ,but I believe the following to be true,I'm sure others know much more than I.
     All cams stock ,(and possibly  webcams based on stock cams-not sure) , have a central passage through their shafts and branches leading to the lobes of the cam that supply oil to the side "cheek" of each lobe , as well as splash lubrication .   Stock  DR650 cams ,have a smaller channel and no passages to the lobes, so the lobes are splash lubricated only .(but I believe one member drilled his DR to stock specs ,restoring those channels).  I don't believe the rocker arms supply any oil.  

The oil supply to the head comes up the right rear of the cylinder in a passage around the head stud.  When the oil reachesd the top of cylinder it then flows in a passage that goes to the left side of the cam.  The oil flows to the cam journals - the left rear journal allows oil to flow to the hollow cam.  The inside of the cam has a small hole on the cam chain side that limits how fast oil can flow out the right side to the cam chain area.  The oil inside the cam can pass through a small hole at the base of the cam lobe - this oil lubricates the cam/rocker surface.....then it flies off and supplies oil to the rocker shaft.  The rocker shaft doesn't receive any oil at pressure - it is oiled by the spray off the cam.  The head has a small oil reservoir under the cam and it likely has a small amount of oil in it while the engine is running - but when the engine stops the oil inside the cam drains out the holes at the base of the lobes and the oil drips off the rocker shafts.....and the little reservoir fills up with oil - and this lubricates the cam at "start up".

The system works well - but at idle there is not a lot of oil flowing up into the head (especially if you have your idle speed set really low).  Idling the engine with the bike leaning on the side stand starves the right cam/rocker for oil - as there is not enough oil flow to push oil uphill inside the hollow cam, and the oil level in the reservoir is on the downhill side and none reaches the right cam lobe.  (Don't idle the bike on the side stand.....and don't idle the engine for long periods of time.

Armen wrote on 11/09/19 at 19:32:42:


Absolutely - each rocker compresses 4 valve springs (2 valves with 2 springs each)......and I believe it is very close to being at it's limit.

With good oil and an adequate idle speed to provide oil flow they can last a long time - Youzguys is at 160,000 miles and climbing on his original cam and rockers.

Thanks DBM
Somewhere in my paperwork is a book of hotrod tips for Nortons. In there is to chamfer the oiling hole for the right cam bearing so it gets more oil.

There are two cams available that require stiffer springs.  They are Web grind 402 and grind 340b.  

Those are hot cams for the DR. They have even more lift and duration than the ones you are thinking of.

batman wrote on 11/12/19 at 08:23:35:


Too radical comes down to the type of riding that you do. If you like to just putt around and don't want to downshift much, the 340b grind is probably a bad choice for an otherwise stock motor. The 402 is about the same as a stock DR cam with a bit more lift and duration. Either of those will require modifications to the LS engine though, as well as the stouter springs.