I have recently acquired a 1969 ironhead 900 sportster that was apart in a garage. Put it back together and it started first bump on the electric start. After about a minute the rear rocker box gasket blowed on the left rear side leaking oil. Tore it down&nbsp\\;replaced the gasket and fired it up again. Rode it about half mile and it blew it out big time in the same spot. I have been told that the oil&nbsp\\;could be&nbsp\\;pressuring up due to blockage&nbsp\\;and I did&nbsp\\;noticed that oil was coming from the bolt holes on the transmission. The drain holes are open on the sides of the cylinder and that is as far as I have checked. Any ideas on what the problem is and be gentle as I am just learning the hard way about working on these things. Probably leaving out alot but it is a start.&nbsp\\;

 

Up by the generator on the bottom of the cam cover is a tube that is open at the end.....this tube is the crank case vent, as the bike runs air pulses should be coming out there....check that.&nbsp\\; Also the enging is vented to the oil tank, if these vents are clogged or not breathing well the engine will be pressured up inside and oil will wnat to excape from every gasket surface.

 

Thanks Doc You gave me more in one paragraph than I have gotten from anyone else in the last three weeks

 

Your Welcome Rosco....
Tell me did you have the oil pump out? Those pumps have a timed crank case breather and if it was installed without timing it the engine won't breathe correctly either.&nbsp\\;I guess what I'm saying is your problem is breathing if it is blowing out gaskets in the rocker boxes, not oil pressure.
Good Luck&nbsp\\;&nbsp\\;

 

I checked with my buddy that turned me onto the bike. He said the oil tank is pressured when he started it earlier. I found a vent tube behind the starter but not the generator&nbsp\\;that I can blow air into and it escapes thru the push rod tube base. He also told me the valve guides had just been replaced on the front cylinder but not the rear would that cause back pressure. I was told to ask you if the new rings on the new pistons would cause a problem if they had not set correctly. I can not say if the oil pump was tanken off or not, it was assembled when I got it but it had all new pistons replaced and I'm not sure what else. I'm dumb as a stump on these things and sure appreciate the info your giving.

 

I tried to reply ...site won't let me send it feel free to call me at the number down below.
If the breather is pluged up front on the cam cover that is your problem&nbsp\\;