Topic: oil priming after engine rebuild.

[_mark]

Hi. After rebuilding of engine, I put for the first time ever the oil in the tank, I removed spark plugs to avoid to load the crankshaft bearings and I opened the oil gallery where there is the oil pressure sensor.
I rotated several times the shaft with the leg kick start but no any quantity of oil is coming to the oil gallery.. is there any chance that the oil is not coming unless a real start/ a electric motor cranking or I mistook something? thanks.

[BenelliSEI]

Did you prime the oil pump the way that is suggested in the manual?

[_mark]

Did you prime the oil pump the way that is suggested in the manual?

you mean to immerge and rotate the pump before reinstalling it? no I didn t

[Jerry Rxman Griffin aka MuthaF'er]

All else fails you may just have to hit the starter button for 5 to 10 seconds and fire her up. This should not create an issue as long as you have used plenty of assembly lube.

Edited: If you do not almost immediately get oil pressure doing this shut it down. Do not RUN it without pressure. I have had to use this method a couple times without any issues. Even using the starter with the ignition switched off and not getting oil pressure can cause damage in short order. Ensure you have oil flowing to the cam by removing the the adjuster caps on both sides/ends of the engine and have rags around the open holes.     

[_mark]

I just put some grease only on the journals. Is it a problem ?



Based on this :

it takes some time the oil to go up and build the rpessure and electric starter must be used.

[bustech51]

Also make sure that when you are cranking to get oil pressure that you have the ignition switch in the "OFF" position.  That helps save the coils from overheating from incomplete circuits due to no plugs installed.

Sent from my LG-H812 using Tapatalk

[Don R]

 I've been known to pump oil into the oil galley or at least pour it full. I used a gauge adapter and pipe fittings once and a tank for adding air conditioner compressor oil to a car several times.

[ekpent]

Doubt kicking it will do much. If you give it a go and start it up have a flashlight handy and be looking in the oil tank for a drop in the level and some good agitation and some bubbles etc.. Pouring a quart of oil or so down through the tappet covers can get some oil into the sump area also before you start it.

[HondaMan]

In the last 8 years I have had to replace crankshafts in 4 CB750 engines where the owners got impatient and started it up without oil pressure. Within less than 10 seconds it spins every bearing and journal on the crank. DON'T start it up until you have oil pressure with less than 2 seconds of electric start turnover.

Here's some tips:
1. If you haven't already: install 2 new Orings at the hoses where they bolt to the engine. These are 2.5 x 15 or 2.6 x 15mm size. Many gasket kits that contain these Orings have 2.4 x 15 size, which is barely enough and often not helpful.
2. As stated above, START the process with immersing the oil pump in not less than 3: of oil in a container, then turning the gear (both directions) until air bubbles stop appearing. IT will help some to crack open the oil PSI check valve (carefully so you don't scratch the piston) to let the low-pressure air bubbles out during this process.
3. After [re]installing the pump into the cases and putting the oil pan back on, pour about 1/2 to 1 quart of oil into the engine. Thicker is better: don't use less than 15w40 for this, and 20w50 is much better. You can pour it in thru the top case vent (I just open the top breather cover to pour it in) or thru a valve cap opening, if you're clever and have a narrow funnel. This oil will help seal the scavenge side of the pump so it will suck a little harder from the oil tank.
4. In the tank: if it is cold in the garage, use 15w40, else use 20w50 oil (non-detergent only in this engine, please) and put at least 3 quarts into the tank to give some mydrostatic head to the pump.

[Bodi]

100% agree that seeing oil pressure - at least enough to douse the oil light at 5psi or so - is vital after a major rebuild before starting it. Not quite so much with a wet sump engine that's had assembly lube used properly but the dry sump 750 can take way too long to get bearings oiled on first start after a rebuild. Beyond needing priming, the pump should never run "clean dry"... I've had one seize solid, rotors basically welded to the case, from running directly after being checked and cleaned with brake cleaner... and not oiled after cleaning.
With plugs out, the starter on a decent battery will get enough RPM to get the light off. Be cautious with the starter, it overheats really quickly even spinning without plugs. I spin about 30 seconds then wait at least two minutes. With parts pretty much NLA, I don't want to cook a starter.

Is there such a thing as "non detergent" multigrade oil? I used to be able to get single grade non detergent but it's getting near impossible to find (50's Dodge flathead six army truck motor that's never heard of detergent oil, guaranteed to spin bearings, throw rods and such - if detergent oil loosens that 60 years of sludge). I have never seen multigrade claiming to be non detergent.
And, if I way ask, why non detergent? A fresh rebuild won't be sludged up and coated with varnish (hopefully!) and it's unlikely that any SOHC4 would be a detergent virgin now.

[PeWe]

I had to remove oilpump and prime it again on my CB750 K2. 
(Pump had been taken apart so it was really dry when I primed it first time, but not good enough.)

Real good this time releasing the air inside that block the oil flow.
I had it in a plastic container covering the pump completely.
Block one of the holes ( oil hose holes) with thumb. Rotate the sprocket in that direction you will feel it create underpressure to thumb.

I had to open the pressure relieve valve (14mm nut) to let blocking air out.  The other side of pump too. 2 bolts.

It bubbled when rotating the sprocket.
Do the same with other hole blocking with thumb. Now rotate in the other direction. When you no longer see any bubbles, tighten the 14mm nut.
Tighten it a little harder when pump is installed.
Not too hard, it is very thin and not as a nut/bolt that usually use 14mm wrench.

Continue to rotate and thumb will be sucked into pump rather hard. Then you know it is OK.

I removed pipe 3 and 4 of my 4-4 to get space to remove oilpan.
Then access the pump, remove it no problems.
Prime it and assemble the pump.
My bike was parked on sidestand. I used my telephone selfie cam to see better. Laid down on my back...

Later  same excersize on  another CB750 when it got a rebuilt pump with new rotors.
All air must be out.

Be careful when assemble the pump. It must go on parallel to case to not harm the fragile knock pins, the 3 thin metal pipes with o-rings.
Really easy to dent them unusable and order new.

I have ordered several extra as spares after that experience

My build had assembly lube on crank bearings and cam so I had lube enough to spin starter longer.

No plugs in to let it spin quick and less pressure on rods and crank.
I think a thinner oil should be easier for priming.

With no air inside no problems with 20W-50 as my bike gets.

[BenelliSEI]

Learn d my lesson years ago. Prime the pump after the engine is in the frame, sitting upright. Never fails to make instant pressure....

[HondaMan]

Is there such a thing as "non detergent" multigrade oil? I used to be able to get single grade non detergent but it's getting near impossible to find (50's Dodge flathead six army truck motor that's never heard of detergent oil, guaranteed to spin bearings, throw rods and such - if detergent oil loosens that 60 years of sludge). I have never seen multigrade claiming to be non detergent.
And, if I way ask, why non detergent? A fresh rebuild won't be sludged up and coated with varnish (hopefully!) and it's unlikely that any SOHC4 would be a detergent virgin now.

There is a lot of non-detergent oils out there, but they don't advertise it much, for reasons I won't go into here (it is political, believe it or not...).
The most-common non-motorcycle-specific oils are diesel-rated oils, as diesel fuel and detergents do not get along at all. In cold weather work in my garage I use the Shell Rotella Diesel oil in 15w40 for things like priming, startups, etc. For riding, though, this will be too light in summertime temperatures for the 750 - it is marginally OK for the 500/550 if used in commuting service, like 10 miles or less to/from work. It doesn't keep its body when touring, though.

The best non-synthetic I have found today is the Bel-Ray EXL Mineral, which is a copy of the old Castrol XLR that was developed expressly for these engines, in 1970. Golden Spectro makes the best 20w50 synthetic (non-detergent) that I know of: O'Freen has gone well past 150k miles in his 750F0 with it, too. Be careful with the Spectro: this label has a similarly-marked oil for the V-Twins (H-D) which is VERY high detergent and will foam in less than 1 minute of use. This will damage (as in, wear quickly) the main bearings and will wreck the clutch, making it slip until you pull the plates out to wash them off in gasoline. Many synthetics will do that to these wet clutches, so that path is not so straightforward.

[Don R]

 PeWe's post reminded me of when I removed the cap from an oil pump relief valve, and it seemed to turn easily. Then I noticed the hex part was cracked and had separated from the threaded part which was still in the pump. I never saw that before or since.
   I was glad I found that, it could have cost me a motor.

[PeWe]

I had no priming issues in the 80's when I restored and modified my K6 a few times. I did not take the pump apart, let it sit.
I flushed it with naphta (white spirit) and rotated the sprocket so old dirty oil came out.

The thin oil, mostly naphta mix did not capture oil stopping air bubble inside.

I just started the engine. Mostly kickstart and oil lamp off very soon.

[_mark]

Hi, today I poured some oil in the oil gallery with a syringe and poured some oil from top cover tap.
I cranked the engine and in around 5/7 seconds pressure started to build up. You can see in this video that in the second attempt I stopped because the pressure was going over 3 barg. Any comment ? Oil is 15W50 Motul 5100

https://www.youtube.com/shorts/qBzd8fydnkA


Thanks

[HondaMan]

Hi, today I poured some oil in the oil gallery with a syringe and poured some oil from top cover tap.
I cranked the engine and in around 5/7 seconds pressure started to build up. You can see in this video that in the second attempt I stopped because the pressure was going over 3 barg. Any comment ? Oil is 15W50 Motul 5100

https://www.youtube.com/shorts/qBzd8fydnkA


Thanks

Normal cold oil pressure in this engine is 60-65 PSI. If "bar" is 14.5, 3 bar is about 43.5 PI, slightly low for a cold engine. It may still have air in the pump, so use the electric starter a few more times. 60 PSI is around 4+ Bar.

[_mark]

Thanks

[HondaMan]

PeWe's post reminded me of when I removed the cap from an oil pump relief valve, and it seemed to turn easily. Then I noticed the hex part was cracked and had separated from the threaded part which was still in the pump. I never saw that before or since.
   I was glad I found that, it could have cost me a motor.

That's just scary!

[markmyodb]

Ken at CycleX "gave" me a gear from an old pump that I used in my drill to prime the system.  A failed "new" pressure switch caused me some issues when I was trying to start it, hence the gauge it now has. 

[HondaMan]

Ken at CycleX "gave" me a gear an old pump that I used in my drill to prime the system.  A failed "new" pressure switch caused me some issues when I was trying to start it, hence the gauge it now has. 

That's an interesting new approach!
Ken's always coming up with interesting ideas.