Ladies and Gents, Let me begin by saying Hello and that i'm a newb to the forums so please bare with me. I just completed a top end rebuild on a good friends 71 ironhead which went smoothly i.e. pistons, rings, honed, valve job. Unfortunately, before i began work on the bike he took it to a shop and after the shop tore the bike/engine all the way down they gave it back to him in boxes and thats where i came in. I now have it all reassembled and before i fired it up i hooked a 0-75 psi oil pressure gauge to the oil pump where the pressure switch would screw in and ran the oil return line into a separate container so i immediately knew if i had oil pressure and if it was circulating throughout the entire system and returning. The bike fired on the second stroke and sounded amazing... It ran for about 5 seconds when i noticed the oil pressure gauge maxed out and actually broke the gauge it is now stuck at 50 lbs... Nothing returned from the oil return hose.... I hooked up another gauge, fired the bike and the oil pressure immediately shot over 100 lbs so i killed the engine. So i know i have a restriction and 2 broken oil pressure gauges lol. All of the hoses are new and orifices are clear. I had to reassemble the cams and oil pump when i received the bike as well as have custom cam shims lathed to correct cam endplay as per the Clymer manual. I know the cam timing is correct the bike fired and revved perfect but i did not let it run long for i don't believe there is oil pressure throughout the engine. Could oil pump timing cause a oil pressure spike ?? What would cause such high pressure in the delivery and none in the return ? I did have the whole oil pump broken down, cleaned, reassembled with new gaskets and i am certain the gaskets were identical to the ones i removed.... Does anyone have any insight or things i can check before i get the motor back out to take the pump back apart ?

 

that is normal - the cold start up oil pressure is always extremely high its the way it is

question - did you prime the lower unit with oil say 1/2 of a quart of oil /// if not it could take 4 or 5 min before you see oil returning to the tank

start it up again and ONLY if you hear noises than shut it off / you did say it sounded great i believe

 

I have run a 30 psi gauge at the rocker cover and a 100 psi at the pumps. The 30 got pegged at startup but was a high quality industrial oil filled gauge and was not damaged. The 100 maxed out at around 60 at startup.

If the oil pump was removed and re-installed then the oil pump would have to be timed before the cams were re-installed. The procedure for this is in the Factory Service Manual part number 99484-78. I do not know if an improperly timed oil pump would contribute to this problem or not. I have not done the procedure myself as it is not required on my 1978.

To ensure that the oil pump is primed remove the gauge or switch from the pump and let the bike sit not running until oil drips out. Might need to sit overnight. Might need to remove the oil tank lid.

To check if the oil pump is primed remove the oil pressure switch or the oil pressure gauge and run the engine. Oil should plop out. It will not come out like a fire hose! A small catch pan will be sufficient.

Next check if oil is returning to the tank.

To check if oil is getting to the top end remove the 1/8 NPT pipe plugs from the right front corners of the rocker covers and run the engine. Oil should dribble out. Again, it will not come out like a fire hose. It will not all flow out.

An alternative is to disconnect the metal oil lines that run up to the rocker covers. I prefer the pipe plugs as getting the lines to re-seal can be a problem altho most guys do this with the lines not the plugs. Remove the plugs carefully so as not to strip the threads. If they are really stuck try 10 seconds of propane torch directly on the head of the plug.

 

Mick as you already know - no oil pump has a timing as it constent flow BUT the early bike has a rotating breather that is timed with the cams via flywheels and it in turn drives the oil pump gearing so yea but no < oil pump timing

 

Right. I got my terminology mixed up as i have not had to do that breather timing myself. It is timing the crankcase breather not the pump.

It usually has to be re-done if the oil pump has been removed, before it is re-installed; which is why i thought it might be part of the OP's problem.

 

Okay i know for a fact the pump was primed because it was dribbling out the pressure switch hole... I do remember working on a friends 73' and when i popped the oil cap off the tank with the bike running there was a fare amount of oil pumping out of the return into the filter. I am just nervous that i dont have oil pressure in the crankcase.... Maybe i installed the wrong oil pump gaskets ? i wish there was a way to check without running the engine can i prefill the crankcase ? Also, i have not yet added oil to the primary i just wanted to get the bike fired up first but i don't believe this would cause an issue... Thanks for the help thus far

 

put a quart of 15 / 50 mobil 1 or what ever you use in the primary before you seeze up a trans bearing --

you could use the timing plug hole to add oil - hold on to the handle bars kick the bike over and hold the kicker down than rest the entire bike on the kicker pedal - this way the timing plug is on a up left angle that will help in adding oil

 

The engine will survive OK for some time on very little oil. The oil tank holds 3 qts, the service manual says to top up when down 1 qt so it will run on 2 qts. I have seen respectable expert opinions who say it will run on 1 qt but do not do it too long.

So add in a qt of oil as johnjzjz suggests then do not worry about it too much. Check for oil to the rocker covers and flow to the tank.

15/50 or 20/50 is good break-in oil. Use the same oil in both holes. No one uses synthetic in these engines.

Best i think to start the engine with the oil tank cap off. If you remove it with a running engine you risk an oil spray. I have not experienced this myself only relaying another guy's experience.

I think it is unlikely that you installed incorrect oil pump gaskets or other similar errors.

Did you do the crankcase breather timing? [requires flywheel positioning, lining up a hole in a slot, or whatever - i am not too familiar but details are in the FSM].

How thick are the cam shims that you had made? I have heard that going too thick can cause problems but i do not recall how thick is too thick or what would be the problems.

 

johnjzjz's comment needs repeating..... don't run that motor without oil in your primary / transmission. Seizing your transmission will be your next problem.