blocking rocker oil feed

In the picture of your bike it looks like 1/4 inch line. Last year, my old oil line between the two rockers broke so I used 1/4 inch line to stop the oil spewing and started burning oil and fouling plugs on the left side. I then got new lines (smaller diameter) and this problem stopped. Is this usual?

christulin said:

In the picture of your bike it looks like 1/4 inch line. Last year, my old oil line between the two rockers broke so I used 1/4 inch line to stop the oil spewing and started burning oil and fouling plugs on the left side. I then got new lines (smaller diameter) and this problem stopped. Is this usual?

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if your talking about my profile pic, that was before the bike was torn down and gone over. I have new stainless lines on it now.

ludwig said:

I am confident that you can ride your bike for at least 15 min. or 15 km without any harm , ( 500 + km would probably be ok too ..)

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OK, how about your bike or your car.

I think you can check the intake guide seals with the springs and head and valve in place. Maybe I am wrong on this point.

This thread offers some sound advice as to how to go about systematic diagnostics and information gathering (without shutting off flow to the rocker box). There are suggestions on other things to look at and other ways to look at it.

Ludwig said:

"OK then , I 'll tell you a little story about my bike :
I occasionally check the oil pressure with a pressure gauge , connected at the RH rocker feed thas is normally blanked off .
( drilled trough inlet spindles , so I only have a feed line to the LH side ) .
On one of these occasions , I noted almost zero oil pressure , at 4000 rpm the needle hardly lifted from the stop .
Time to check the oil pump .
Took off the timing cover , and found that the crankshaft oil seal and in the cover had popped out .
My fault : The circlip was likely not fully seated ( hey , I'm not perfect ..) .
This was after a 7000 km trip to Portugal and trough some VERY hot weather in Estremadura , Spain .
Looking at the wear marks on the circlip and the small cover plate , it must have been like this for many 1000 km , possibly the entire trip .
There was no damage to the engine .
Oil consuption over the trip was neglible ( lees than 1 L .) .
The reason the big ends survived is because the crankshaft itself acts like an oil pump trough centrifugal force , camshaft got his usual oil splash ,

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I am with you up to this point. But it falls apart with conjecture when you state:

Ludwig said:

but the rocker spindles must only have got a trickle of oil for 1000's of km .

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So they must have, how refreshing.

Well maybe a trickle is all they really need or maybe you just don't realize the damage done or maybe they received ample oil. So maybe you are the one with X-ray eyes or did you dismantle and benchmark against what you started with in spindle diameter etc....

Ludwig said:

And telling someone who's engine is puffing blue smoke to " check the plugs " , is not "sound advice" , but kicking in an open door .
More than likely his plugs will look oily ( surprise !) , so what did he learn ? .
Compression check is allways good , though ..

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Well dry plugs tells me you are leaking oil from the exhaust guides - end of story; but you did not figure that one out until now - (no surprise!). So after you Messieurs' while holding the door wide open for you.

Also one dry plug also tells you which cylinder is the problem.

All one has to do is open ones eyes and mind a bit.

Quid pro quo and the art of motorcycle maintenance. 8)

This subject was covered in roadholder magazine decade+ ago. I found the link I had.
I followed John Hudsons advice then re blocking the rocker feeds, and the smoke stopped. In my case then, the smoke was caused by a loose rocker spindle turned in the head allowing oil to flood straight out the spindle/rocker hole over-oiling the head.(The standard rocker spindle plates do not work)

I've no evidence to guarantee blocking the feed would not damage anything, but I respect JH's advice on that one.

Just my 2p worth

http://www.nortonownersclub.org/support/technical-support-common/smoking-engine

ludwig said:

L.A.B. said:

.. but have you already checked the more obvious things that might lead to top-end over-oiling, such as inlet valve oil seals popped off the guides, ..

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and how would you do that ?
By pulling the head , I suppose ?

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None of the things I suggested necessarily requires removal of the head.

Kevbo82, first off I'm a Triumph guy so for what it's worth, unless Norton oiling systems and top end components are way different than Triumphs (don't think so), I don't see a problem in blocking off rocker feed oil for a few minutes or a few miles for test purposes. When Triumph went to nitrided cams, they quit worrying about the oil feed to cams/lifters and more than a few old time and current Triumph dragsters run no oil to the top end, they just squirt a drop on each valve stem before a run, their cams and lifters are oiled by crank throw off, nothing coming down the pushrod tubes. Both Norton and Triumph use end feed cranks and will live on gravity feed for reasons Ludwig mentioned, but no need to test this so block off any oil feed line removed.

I've heard Nortons have a problem with 'wet sumping' could this be your problem, just a thought.

By all means, do as suggested to narrow down your potential problem, check plugs, piston crowns with a flash light at TDC, comp. check etc. but I don't think blocking off the oil feed is a big deal but get all available clues starting with the easiest first...before you start dismantling...Mark

I am not an expert at much of anything. But I love a thread the pulls Ludwig out of the wood. How about a leak down test? I salvaged a manifold and gauges off a portable compressor that had stopped compressing so that I can make a leak down tester from it. I have never performed the test, but it is on my event horizon. But it makes some sense as to why one might use it as a tool.

There are tons of videos on using and building leak down testers on Youtube. As to how long you can run it without oil...hmmm, I suspect longer than any of us are brave enough to do on purpose. I might instead remove the intake cover, since that is usually the side that causes the problem, unless oil is leaking in on the exhaust valves while parked. Use a shop vac to remove the oil from the intake side while the bike is running. Like your dentist does to remove drool while they work on your mouth. At least this way you would be getting some oil to the cam via the front tubes but should be able to keep enough oil out of the intake valve box to see if it reduces the oil you are consuming. And yeh, it will probably make a mess, and yah you will wish you had a helper, and yeh, you will probably curse me for suggesting this once you try it.

Russ

ludwig said:

but to check the guide seals you have to remove the springs , and of course we all know how to do that with the head in place .. right ? .

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No, not necessarily.

To check the guide seals are in position (and not riding up the valve stems) it is only necessary to remove the inlet rockers and then check each inlet valve by looking in through the exhaust rocker ports as it's possible to see the inlet valve stems from that position (a small lamp or bulb may be needed).
Alternatively, a small mirror could be used on the inlet side. If a seal is off the guide then it should be apparent.

I have never been fond of the small oil drain in the head, inlet side, once run a 650 ss with the rocker cover off.
The space between the inlet valves filled up with oil and was not drained away, there was a reluctance for the oil to drain, it appeared that the pistons falling caused the oil the be pushed back up the oil.
Racers drilled a hole between the inlet valves ,so i did the same, connected a 1/4 bore tube to the "new drain" and plumbed it into the timing side, i placed a none-return valve in the New return line, i sucked the oil out when the pistons rose!...worked great!
I was bragging to Les Enery about my mod, he smiled and said , "race lads did that years ago" same reason the" original drain struggled" .
I could see oil rise above the seals before the EXTRA drain.

john robert bould said:

"race lads did that years ago" same reason the" original drain struggled".
I could see oil rise above the seals before the EXTRA drain.

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Interesting perspective. I never heard of a properly assemble Norton needing more than the factory drain but at sustained engine races speeds maybe it is not enough. I know with my sleeved down 850 Commando road racer there was never a problem. No fancy breather valve, all stock configuration. Never over oiled and never smoked.

I always thought the only reason for the center drain and external hose was if the act of opening the ports for performance ended up breaking into the oil drain hole on the RH inlet side of the RH port. The drain hole would be epoxy filled and the new center drain was then required and installed.

As for a few minutes without rocker oil feed, probably not a problem. Going without rocker oil feed for hundreds of kilometers as someone suggested, is not recommended as you will have damage. Maybe this is what someone got away with but there is more than likely damage.

So blocking the oil feed to the rockers will tell you "it's the head" and not the rings. I would still want to know if it were an intake, an exhaust, one valve, a guide seal or a crack in the intake port so I would perform some of the simpler tests anyway to get more information before tearing into it. To me it makes the "block the rocker oil feed line" test more or less redundant. I would not do it unless it were a last resort and cannot figure it out with the simple tests recommended throughout this thread.

Just my 3 pence.

If its smokes or leaks within 30 sec of start up then its not head leaks as it takes about that long to get oil up to head and about that long to pump down wet sump excess splash on bores for ring to wipe off or miss to smoke or blow by out weak spot. Rings tend to seal better once heated and rpms up while heads tend to leak or smoke more and more on rides. I think leak down is just extra work before taking apart anyway and must be very careful not to let piston get pass exact TDC or risk damaging spokes with a bar shoved through as no way is rear brake able to hold the sudden piston push to bottom, as must be done to check ring seal just below TDC where most ring-bore wear occurs, for blow by pressurized leakage.

Best thing I leaned from my leak down turmoil was determine exact TDC mark on magnet rotor. Ring blow by was detectable by air sound coming from open intake cover just past TDC as air got into cases then up oil drain hole in cylinder, but about missed d/t the spoke about bending and me and my buddy hard breathing holding on gritting teeth. Please video any leak down attempts for our educational entertainment.

Heads mainly need excess oil to splash to cool springs, if ridden hard but hardly any oil otherwise for quite a ways though not 100's of miles. One thing Nortoneeering taught me is ain't no short cuts in mainlining them or likely just get put up till someone with good will power and resources recovers em.

I don't recall ever reading or seeing anything on a leak down test for a four stroke. What are you trying to achieve that cannot be achieved through a compression test. How would you distinguish between a leaking ring set and a head gasket and a valve. I suppose you could listen for air leaking past a valve but by then you have a big valve problem if you can hear it. I think the typical compression test WOT and then do it again after adding a few squirts of oil in the cylinders will tell you all you need to know.

A crankcase breathing two stroke is a different matter where a leak down test will indicate the performance of the crankshaft seals, a critical component of the two stroke performance. This test tells you nothing about the two stroke ring conditions. A compression test is required for that.

In 4 tokers, Compression tests just test compression or lack of it, but not the path of loss. Leak down tests, Ring &/or gasket leak would pass air to crankcase then sounds out breather pipe, oil tank or intake box oil drain. Leak past valve or guide would be heard out the carb or exhaust paths and/or the intake box drain like the rings or gasket, doh'. A real Nortoneer should be able to differentiate this, after a few successful leak repairs to calibrate ear. For the novices like me, nothing for it but put risky riding on hold, dig in and fix everything examined yet still suspect. Otherwise just live with you own disgust as others say yeah all Brit Iron does that.

Only from the hobot. :lol:

So where did I put that handy nomogram for the four stroke leak down "Uh-doh" test.

So on a Norton Commando, how much hiss out of the oil tank is too much and at what pressure do you test at?
Do you pressure it up and let it "leak down" like a real "leak down" test performed on a two-stroke or are you just pressuring it up to see what happens?
Does this same pressure/hiss relationship stand true for a BSA A65? How about a B50?
I suppose you could also listen to the hiss out of the exhaust pipe but what reference chart do you go to if it is fitted with a Peashooter or a can type silencer. What do you do when it leaks down fast and there is no hiss - oh my.

Ugh John, the www has details on how to do proper leak down tests. Main use is to decide on wear state if better to rebuild now or ok to wait a while more on less effective compression. No air sounds is the normal expected hoped for result. Need pressure over 100 PSI to be more effective but less will work, just not as good to hear or measure the wear-leakage percent differences. If not hearing leaks at TDC next step is let piston move down slightly in stages to see if that reveals ring seal issues. Trick is only let move tiny bit or two things can happen, one, the valves begin to open to let test PSI out, or engine gets away with some decent torque. I think the smart Nortoners use a block or such in primary to limit motive but less smart more lazy fellas might skip that safety step. A stethoscope like tube helps isolate sound from surrounds. I invited Wes over to help me and its one of the hi points of comedic waste of time around a dangerous machine. Compress leak down may reveal oil smoke source but not external leaks as no oil flowing to blow out.

Here's a link that ultimately states

http://www.dansmc.com/leakdown.htm

Which the author summarizes rather nicely by stating:

"Well, I think this is an interesting test that isn't really necessary for most motorcycle engines."

The problem with a "leak down test" is having a criteria to work to. This would be a table of pressure loss over time for a given engine configuration. This is simple for aircraft as they are more or less standard and there is likely decades of data on true leak down rates. If someone has a time-pressure table for a stock Commando showing leak down say starting at 100 psi with some threshold of acceptable leak down rate then you have something to work to. Even then it does not distinguish between intake valve leak, exhaust valve leak, head gasket leak or ring leak. Furthermore, you can have good compression (leak down results) yet still be pushing oil past the rings. Just a few weeks ago a fellow on the list was experiencing smoking from his Norton with new rings and we come to find out he trimmed the oil control expander.

Here is a quote from the above article. Notice it says something about giving "one piece of very valuable information". Value is in the eye of the beer holder as they say. I certainly wont try to sell a test that I have never performed myself. But I would rather listen for air leaks and try to interpret that, than listen to my followers bang on my cam with no oil while trying to see if I was making any smoke.

"So what does all this mean to you. Well, I think this is an interesting test that isn't really necessary for most motorcycle engines. However, if you ignore all the percentages and green/yellow/red zones, it does give one piece of very valuable information. It tells you where the leaks are and you don't even have to have the gauge to do it. "

What this fellow is proposing is that you blow air into your cylinder and just listen for leaks without trying to measure the percentage of loss. Interesting idea!

Is it correct that we are diagnosing a bike that is freshly rebuilt? Have the rings had a chance to seat? Is it smoking on start up? On deceleration? The symptoms described here are actually pretty vague. Before deciding a proper course of action, it would seem to me that some basic logic should be applied. Oil from the crankcase doesn't tend to leak into cylinders while the bike is parked! Just asking...

Russ

If you think a leak down test is the way to go I was told to use the snapon mt324 low pressure gage. I don't know the details but its preffered by race tuners and approved for aircraft use.

http://www.ebay.com/csc/i.html?_kw=Snap ... 0520439334