1971 900cc Ironhead
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Stage III
Joined: Nov 2014
Posts: 3
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From: Montoursville, PA
1971 900cc Ironhead
Ladies and Gents, Let me begin by saying 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. 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 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 and it did the same thing. So i know i have a restriction, all 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 Clymer. I know the cam timing is correct the bike fired and revved perfect but i did not let it run long. 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 they 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 ?
Stellar HDF Member
Joined: Aug 2009
Posts: 3,212
Likes: 212
The oil pump doesn't get timed. The breather does. But that doesn't affect the oil pressure. You've got a clog or misroute somewhere. Where exactly did you hook up the pressure gauge? If you put it in the wrong spot you can actually block flow and get a false high pressure reading.
Cold starts on an ironhead might read 30-40psi, but that drops off quickly. They simply are not high pressure motors in any way.
And I'm with John, us Ironhead guys pretty much hangout at the XLF ironhead section. I only venture out because I own an Evo too.
Cold starts on an ironhead might read 30-40psi, but that drops off quickly. They simply are not high pressure motors in any way.
And I'm with John, us Ironhead guys pretty much hangout at the XLF ironhead section. I only venture out because I own an Evo too.
Last edited by Scuba10jdl; Nov 5, 2014 at 08:20 PM.
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