Topic: Engine Half Assembled, No Oil Flowing, Me Concerned...

[OldSchool_IsCool]

1977 550K US Model

I'm putting my engine back together after a top-end rebuild, did not split the case.  Did remove the clutch basket.  New rings, new cam chain, new tensioner, new gaskets and O-rings from the base on up.  New oil filter.

After doing the initial torque of the head nuts today, I decided to put a quart of oil in her and make sure I'm getting oil flowing to the cam bearings.  I'm holding the cam chain with my fingers, allowing it to roll around.  An assistant is using the kick starter to turn the engine slowly with bike on center stand.  We do this for about 2 minutes.

First thing I notice is the cam chain is not drenched in oil as I would have expected.  No oil has come up to the cam bearings yet either. 

OK, maybe not enough oil in yet.  Add another quart and repeat.  Same results, no oil on cam chain, no oil coming up thru the galleries.

Top off the crank with oil try some more.  STILL no oil on the chain and no oil coming through the galleries.  Kicking harder didn't help it either.

What am I missing here?  Shouldn't I have an oil-soaked cam chain with a full sump?  What RPM do I need to get to before the oil pump has enough grunt to push oil to the cam bearings?

[kayaker43]

Doesn't surprise me too much, Even if kicking fast it would take quite a few kicks to build up. That's why you should always use a moly based assembly grease. Once running, it could still take a few seconds if the filter was drained too.

I use gear oil on cyl walls and cam chain, and moly assembly lube on crank and cam bearings, cam shafts and rockers. Some people will use the starter to crank with ignition disabled to build pressure, but you still want assembly lube even for that. On some cars and bikes, you can find an oil galley plug and use a squirt bottle like gear lube comes in. It is possible to squeeze by hand and get the oil light to go off. This fills the pump, filter and passages. One last tip, fill the cam wells with oil so they dip with each turn.

[OldSchool_IsCool]

Thanks Kayaker.  I'll coat the cam chain and cam surfaces with some moly assembly lube and fill the cam wells with oil and keep on wrenching!  I didn't want to use the starter motor as I knew it would take some time and I didn't want to over work the little sucker.  Besides, my electrics are not yet complete.

[MCRider]

I'll say first, I defer to anyone who knows better and this is a WAG. But permit me to participate.

To assume the camchain would be sitting in the sump oil, you would have to asume that the lower 40% of the crankshaft is spinning in the sump oil as well. The cam chain sprocket on the crank is smaller diameter than the crank counterweights.  I can't imagine that any of the crankshaft spins in the sump oil. That would be a huge drag on performance. The rod journals are pressurized so they don't need to sit in oil.

Rather i would assume the cam chain gets its oil from splash feed when the engine is running. It doesn't need much, just a bath in the mist would be fine I think.

I do know on a rebuilt CB750 it takes several, 10 to 20 seconds of the engine running before one can detect oil in the rocker area splashing about. So kicking yours may not result in oil under pressure getting to the cam journals.

Assembly lube is the way to go.  Once you get it started, leave the outboard tappet covers off and wait 10 to 20 seconds to see some oil flinging off the bobbing tappets to let you know its flowing to the top end.

[OldSchool_IsCool]

Thanks MC, that makes a lot of sense.  I read somewhere that the cam chain sat in oil, but with deeper reflection, I bet it's the PRIMARY chain and not the cam chain that rides that low.

So far, it sounds like what I'm seeing is to be expected and I need not be concerned.

[MCRider]

Thanks MC, that makes a lot of sense.  I read somewhere that the cam chain sat in oil, but with deeper reflection, I bet it's the PRIMARY chain and not the cam chain that rides that low.

So far, it sounds like what I'm seeing is to be expected and I need not be concerned.

Certainly, primaries are in the oil.

Kayakers pre-lube tips very good also.

[HondaMan]

Old School: don't overlook the fact that this is a dry sump engine. The pump will not push oil from the crankcase into the filter or journals: only into the oil tank. There has to be at least 3 quarts in the tank on a dry startup to fill the journals. If the crankcase is full and the oil tank empty, the pump will not prime itself, either. This has caused some confusion for our 'brother' SOHC4-ers before...

Next: after any rebuild, I put 4 quarts in the tank, turn on the power to the oil switch and light (or an ohmmeter), and kick for a while, even electric start a bit. It takes about 40-50 kicks in constant, quick rhythm to get the oil light to drop out (i.e., 15 PSI, or thereabouts). It takes 25 PSI to get oil to the cam bearings, because of the leakage below and the restrictors above. Since there is a check valve in the oil pump, and external oil pump (like on an electric drill) can be used to pump directly into the journal on the back of the cylinder block, if you have an extra oil cap that you could install a tapped fitting into for such a test.

A wise precaution you're doing here, IMO. If we can come up with a good solution, we should ask Bob W. to put it into the FAQ...

[MCRider]

Old School: don't overlook the fact that this is a dry sump engine. The pump will not push oil from the crankcase into the filter or journals: only into the oil tank. There has to be at least 3 quarts in the tank on a dry startup to fill the journals. If the crankcase is full and the oil tank empty, the pump will not prime itself, either. This has caused some confusion for our 'brother' SOHC4-ers before...

Next: after any rebuild, I put 4 quarts in the tank, turn on the power to the oil switch and light (or an ohmmeter), and kick for a while, even electric start a bit. It takes about 40-50 kicks in constant, quick rhythm to get the oil light to drop out (i.e., 15 PSI, or thereabouts). It takes 25 PSI to get oil to the cam bearings, because of the leakage below and the restrictors above. Since there is a check valve in the oil pump, and external oil pump (like on an electric drill) can be used to pump directly into the journal on the back of the cylinder block, if you have an extra oil cap that you could install a tapped fitting into for such a test.

A wise precaution you're doing here, IMO. If we can come up with a good solution, we should ask Bob W. to put it into the FAQ...

I always appreciate your tips. And the hard data is amazing.

I think OldSchool is working on a 550. Wet Sump? Or a hybrid?

[Bodi]

The 550 is a wet sump, HM must have missed the model and assumed a 750.
The trochoidal oil pump is a pretty decent bit of machinery, but it isn't a great vacuum pump. Before it can pump oil to your engine it has to suck it up from the sump, a few inches below. There is a bit of clearance between the pump's rotor lobes and between the rotors and the housing ends allowing a bit of leakage - thick oil laks very little but thin air can get through pretty easily.
So to have enough suction to pull oil up to the inlet takes a fairly high pump RPM. As soon as it draws up the oil it will pump quite nicely. With the engine running at even idle RPM it will "prime" - suck the oil up from below - within a second or three. With a dry motor (sat long enough to drain the galleries, and with a new filter) once it starts to pump it has to fill the filter housing and then the main gallery across the engine just behind the filter bolt... then it can come out to feed the top end galleries in the cylinder block (or spurt up from the base gasket face where those galleries would start).
That takes quite a few turns even if you managed to kick-spin the engine fast enough that the pump made enough vacuum to prime.
I really doubt that you have a problem. The pump is quite simple and durable: assuming it worked before you began the top end work, it should work now. I would drizzle some oil down the cam chain and use a bit of assembly lube on the cam bearings and lobes. Oil the pistons and rings before assembly. It is possible to fill the "swimming pools" (these provide cam lobe lubrication on startup before the oil flow gets up there)  in the head once the engine is in the frame, using a pumper oilcan with a long flexible nozzle through the tappet covers.
Nothing diagnoses oil pump function better than a pressure gauge. You can fit a temporary one or add a permanent one simply - drill through and tap for 1/8 NPT the right side plug on the oil gallery (big hex headed thing on the right end of the motor casting, screws out easily for drilling and tapping). Screw in a cheap temprary gauge or run a line to a better quality fluid filled permanent gauge. Just install a brass plug in the hole afterward if you go temporary. Put a plug and required tools in your travel toolkit if you go permanent... you can expect the line or gauge to develop a leak at the worst possible time.

[HondaMan]

Oops.
I missed the very first line of his post!
Yep, I was thinking 750, sorry... been working on 2 of them all weekend!
 

[anparkinson]

I did pretty much the same as you on my CB550K3. When all back together I just spun it over on the starter without the plugs in for a few seconds at a time so not to overheat the starter. Oil pressure came up fine although it took a while before the light went out as it had to fill all the galleries and filter housing first.

How did you replace your cam chain? Did you split it?

[JLeather]

I thought you weren't supposed to use moly assembly lube on these engines because it will get into the clutch plates?  I assemble mine with just some SAE 60wt for assembly lube, no additives whatsoever.  On my car engines I always assemble them with a 50/50 mix of STP and 10w-30, but I won't use it on a wet-clutch engine.

[OldSchool_IsCool]

I did pretty much the same as you on my CB550K3. When all back together I just spun it over on the starter without the plugs in for a few seconds at a time so not to overheat the starter. Oil pressure came up fine although it took a while before the light went out as it had to fill all the galleries and filter housing first.

How did you replace your cam chain? Did you split it?

Yes, split the chain and used a soft link from a 400T to make it endless again.  Actually, this was one of the few procedures on this project that I farmed out to a local semi-retired shop owner who worked on these bike when THEY were the modern sport bike!  He also honed the cylinders and chased the spark plug holes for me.  So the results of this project are pretty much all mine, be it glory or disappointment!

HM, your advice is ALWAYS appreciated!

[Bodi]

I use Redline assembly lube - it's bright red and I don't think it has any moly in it. You get a tiny jar of it with Megacycle cams, I hope they wouln'd supply stuff that would damage your clutch!