Topic: Oil Tank Question... breather/overflow

[.RJ]

Which tube off the oil tank is the overflow, and which one gets attached to the engine?  The top tube is the same size as the one on the motor, so I assume thats the breather.

Just want to make sure...  I put 2 qts in the oil tank and when i turn the engine with the kick starter none of it seems to be going into the sump - how much should stay in the tank?

[754]

As far as I know, the oil pump will actually have to pump the oil out of the tank into the motor.

So if you are tying to do that  by kicking, you may get it going through by next weekend.. It will be quicker if you start it.

[.RJ]

As far as I know, the oil pump will actually have to pump the oil out of the tank into the motor.

Kickstarter doesnt turn the oil pump - or does it not turn it fast enough?  I've never split the cases on a 750... so I dont know exactly how the oil pump works

[754]

It turns it at about 25 rpm, till you get tired.

Motor can turn at 1000 rpm idling, more if you give er throttle..

[lordmoonpie]

Kickstart pinion gear is used to drive the oil pump - hence if you remove the kickstarter you can't remove the pinion gear. The pinion gear is the intermediary that transfers drive to the oil pump gear...

[.RJ]

It turns it at about 25 rpm, till you get tired.

Motor can turn at 1000 rpm idling, more if you give er throttle..

True... I was hoping to build a little oil pressure with the plugs out before I start it up next week.

So where's the breather/overflows go? 

[.RJ]

Hmm... should search first

http://forums.sohc4.net/index.php?topic=8022.0

not sure if this is totally correct, but on my 72 I have it set up with the tank top overflow/vent tube going to the ground, and the smaller diameter bottom hose connected to the back of the crankcases. All is working fine, so assume it is ok. Hope this helps lumbee.

[.RJ]

How fast does the engine need to spin to draw new oil in from the oil tank?  I pulled the plugs and spun the starter (battery is near dead, so it didnt spin very fast), and then pulled the sump plug - it looks like none of the new oil had found its way in to the sump.

[Bob Wessner]

You should be able to get the oil light to go off by spinning the starter for several seconds. Easier done with the plugs out. If it goes out, it's an indigation of oil pressure at least.

[.RJ]

Thanks - not sure how long the engine has been sitting, but I poured 1qt into one of the tappet covers and 2 qt in the oil tank, and I've got the jump box charging up.

Some searching of the site shows some have dropped the sump and taken the spring out of the oil feed stopper to get the engine primed up - should I consider doing that as well?  I'd have to drop the exhaust to get one of the sump bolts out, which I'm not to keen on doing (it was a pain to fit the 4-1 on the bike) so if there's another way I'd like to know.

[754]

If there is any oil in the motor 30 seconds of running should get pressure..and not hurt anything.

make sure it cranks over by hand.. first..

if you put a QUART in the valve cover and it leaked into the cylinder it may hydraulic..  hopefully not..

[.RJ]

if you put a QUART in the valve cover and it leaked into the cylinder it may hydraulic..  hopefully not..

Even with the plugs out?  I'll drain some out...

[754]

If the plugs are out, turn the kcker by hnd. If no oil comes out the plug hole you should be OK. If you can see the oil in the plug hole, it could foul the plug.

It probably ran down the drains and camchain cavity, they are pretty big holes.

[.RJ]

No oil on the pistons, so I spun it over with a charged up battery and the plugs out... took a while, but the oil pressure came up.

[.RJ]

Hmm... should search first

http://forums.sohc4.net/index.php?topic=8022.0

not sure if this is totally correct, but on my 72 I have it set up with the tank top overflow/vent tube going to the ground, and the smaller diameter bottom hose connected to the back of the crankcases. All is working fine, so assume it is ok. Hope this helps lumbee.

The top vent, I hooked to the back of the crankcase - both are 1/2" fittings - and I had a hose that came with the original oil tank that dropped right in place.  The bottom tube is 3/8", and I routed that to the ground.  The parts diagram I looked at, here, says that the top (larger tube) is the breather (although that could mean it breathes to the ground?), and doesnt show anything for the lower, smaller fitting.

http://www.mediafire.com/?bkzwqkn0kjt (Page 110)

The problem is, on the bike's first ride, the tube I hooked to the bottom of the oil tank (3/8") is blowing oil out of it, and onto the rear tire.  This isnt good.

Did I hook the hoses up backwards?  Can I just run an open breather filter on the back of the engine case and cap off the oil tank breather?  Will this hinder the oil draining into the crankcase at all?  I assume not, but I dont want to end up with a crankcase empty of oil either.

Halp! 

[Aaron J Williams]

The small tube from the oil tank goes to the fitting at the back of the transmission and the big hose vents to the ground. You can put a little filter on the valve cover but originally it had a hose which also vented to the ground.

[andy750]

The small tube from the oil tank goes to the fitting at the back of the transmission and the big hose vents to the ground. You can put a little filter on the valve cover but originally it had a hose which also vented to the ground.

+1

As Aaron says the small hose at the bottom of the oil tank goes to the small hole at the back of the engine - next to where the carboverflow tubes are fixed by the small clasp. The breather goes to ground down the side of the frame. Same for the breather tube coming from the valve cover. Depending on your oil tank the rear bottom tube that goes to the engine may be large (approx same diameter as valve cover breather tube) or if an earlier year (<75) will be a narrower diameter tube.

good luck and bikes looking good!

cheers
Andy

[.RJ]

Thanks   I'll get that fixed up tonight.

I'd ride it if the DMV wasnt being a pain about getting the thing registered as 'antique' :mad: