Topic: No oil pressure on my 970cc

[awiertalla]

Hey guys,

I posted about this awhile ago, and since that I have got the bike running, but I have no oil pressure. I have a rebuilt pump by cyclex, and when I first got the bike running, I had low oil pressure (around 5psi) reading by a gauge at the side galley port. I since then traded the pump out with another pump from cyclex, primed it and reinstalled. I have verified that my oil metering jets and in place, with o-rings at both sides of the cam towers. I am getting oil to the top end, but im reading 0psi on my gauge now. Is it possible I got a bad gauge? My dummy light does work, it came on when it overheated the one time I rode it, it normally is not on.

A big question I have is my set up. I am running 78 lower engine cases, but an early 70's cylinders and head. Would this cause the pressure issue? I also have an oil cooler and remote mounted oil filter behind the engine. When the bike first ran, I had a leak coming from the top fitting on my oil cooler, so it makes me believe that I had  pressure enough to get oil to my cooler.

I am about to completely disassemble the motor to check the case oil passages are clear, but wanted to post here first to see what you guys think.

A secondary issue is my header temp, 1 and 4 are twice as hot as 2 and 3 (400 to 220 respectively). The head itself measures 160-175 across all 4, but the headers are vastly different. I am running Mikuni 2 into 4 carbs, so one carb feeds 1 and 2, the other 2 and 3

List of parts:

Ported and polished head with oversized stainless valves and h.d springs (done by APE)
970cc weisco pistons and jugs (bored and honed by cyclex)
Kenny D cam (brand new, I didn't trust the old one I bought off ebay)
Mikuni 34mm 2into4 carbs
h.d engine studs
knifed and lightened crank with cyclex connecting rods
exposed stator
cyclex optical ignition
Moto Gadget M-unit, m-button, rfid key
oil cooler with remote mount filter
undercut racing transmission
cyclex 2 plate racing clutch
gsxr front end with cognito moto rim

I haven't skipped on anything with this bike, which is why I am so frustrated it's not running properly.

[Cb750 Racer]

Since the oil pump is run off the kickstarter on these engines, I would make sure everything with the kickstart mechanism is squared away because that sounds like it's the root of your problem.

[awiertalla]

It is a kick only bike, the starter motor has been removed. If the kicker functions and turns the bike on (which it does), would that imply that it is functioning correctly, or can it kick over and still not be operating the oil pump?

[scottly]

I also have an oil cooler and remote mounted oil filter behind the engine.

The remote mounted filter and/or the cooler may be suspect? Try using the stock filter and housing.

[awiertalla]

I also have an oil cooler and remote mounted oil filter behind the engine.

The remote mounted filter and/or the cooler may be suspect? Try using the stock filter and housing.

I don't think I have the old housing any longer, but that's not a bad idea, at least to rule out the cooler and filter. I can source one off ebay and see what happens. It was just strange that I had low pressure in the very beginning and now I have none. I wanted to do the block off plate with filter, but it sticks out to far and hit the exhaust, which is why I ended up doing a remote mount filter.

[754]

 Did you check or change the guage..?

[awiertalla]

Did you check or change the guage..?

I pulled the gauge off and verified the galley was clear up to the top end. I have not swapped the gauge from my other sohc. I know it doesn't mean much, but it is a brand new gauge. I also did have that 5psi reading in the very beginning.

Also, can you tell me if I am okay running an early top end on later model cases? I'm really worried that I made a big mistake with that, because I have so much invested in both upper and lower portions of this motor.

[dragracer]

Oil flows from the tank through the lines into the  pump which is driven by the kick start idler gear. From the oil pump it flows through a passage on the lower case half to the hole at front of the engine for the oil filter housing. It then flows into  the oil filter housing, past the filter and into the filter bolt where it then goes to the passage in the oil gallery on the top case where the oil pressure sending unit is located. Oil then flows from the gallery up several of the studs to the head. It also travels through the gallery to the main bearings. I'd take that oil adapter set up off temporarily and crank the engine over to see if oil comes out of that lower hole at the front of the engine to verify the oil pump is working. I went around and around with an oil pressure issue until I realized I left the dang idler/ kick start gear off when I installed a lockup clutch. Gad to remove the engine and split the cases to correct my idiotic oversight. I don't think you need to pull the engine to correct your problem. I even fabricated a preluber from a pressurized garden sprayer to be certain oil was pushed to the top of the engine before I tried to fire it up.

[PeWe]

You have stock oil pressure sensor that will lit the oil warning lamp when pressure is too low?

I had pressure issues at last build I never had before. I had to untighten the releif valve on pump to let bubbles out. I had cleaned it earlier and made sure the valve inside could easily move.
Drowning pump completely in a bath with fresh motor oil and turning the sprocket a lot in both directions was not enough when air was captured inside. When air was out, I felt how pump sucked when blocking any of the 2 holes by thumb, rotating pump sprocket.

In earlier builds I had usually flushed it with naphta to clean it and moved sprocket to get dirt out.  No pure oil fill. Thinner solution was probably easier for the air to come out, not blocking the pump.

[awiertalla]

You have stock oil pressure sensor that will lit the oil warning lamp when pressure is too low?

I had pressure issues at last build I never had before. I had to untighten the releif valve on pump to let bubbles out. I had cleaned it earlier and made sure the valve inside could easily move.
Drowning pump completely in a bath with fresh motor oil and turning the sprocket a lot in both directions was not enough when air was captured inside. When air was out, I felt how pump sucked when blocking any of the 2 holes by thumb, rotating pump sprocket.

In earlier builds I had usually flushed it with naphta to clean it and moved sprocket to get dirt out.  No pure oil fill. Thinner solution was probably easier for the air to come out, not blocking the pump.

This is all great info. I am thinking now, that I am just going to do a complete rebuild on this. When I started the project, I had no idea ir would end up at this point. The cases look really bad, there are some welds on the frame that look like crap. I think I am going to have the cases vapor blasted, fix a few issues on the head, clean up and repowdercoat the frame, really make it a show quality bike.

[Don R]

 I'd want to solve the issue before rebuilding it and realizing I have the same problem later but on new parts.

[Tintop]

I'd want to solve the issue before rebuilding it and realizing I have the same problem later but on new parts.

+1

[dragracer]

What those guys above me said

I'd want to solve the issue before rebuilding it and realizing I have the same problem later but on new parts.

[awiertalla]

Bad news: piston skirts are trashed. I'll be getting new pistons and sleeves for it.

I'm going to reassemble lower cases, leave the pistons on cylinders off, put oil in the case directly, and kick it over to see if I can get oil to the galley and stock filter housing. If I can get just to work, I'll assemble and try again.