Low oil pressure is good

[panfreak]

For what it is worth, I thought some might find this interesting:
I was out for a ride last night, and passed a guy riding another old tank shifter which is rare in these parts, so I spun around to shoot the shit. Great guy, turns out it was a '49 pan with original springer that was optional that year. The bike had a TON of miles on it, this was obvious. he had changed a few things, the oil filter was changed to a spin on, he had a cooler mounted out front, butchered battery box to fit big 12V, but still had the linkert and a load of other original parts. I commented on how leak free it was, because although dirty, I could hardly detect any oil, how often does this happen? He showed me how he tapped into both pan covers and ran a hose to the carb filter backing plate to relieve pressure like the newer bikes. He also claimed that he has tried to reduce oil pressure wherever possible because he felt they had too much anyway. His words were actually "if I get any pressure at all, I know something is wrong." ???
This sounds totally bizarre, but trust me, we talked for over an hour, this guy is in his fifties and knows his bike inside and out, has owned it for 20 years I think he said. I plan on hooking up for a ride together soon, I hope to get a pic of his bike and will post for you.

[51Hog]

Someone correct me if I am wrong.
It seems to me that he was talking about blow by pressure and or crank case pressure.
If he was just tapped into the Pan covers, he would not be relieving oil pressure. He would be relieving the pressure in the rocker covers caused by leaking valves. The pressure would travel past the valves and through the valve guides. If he needs to relieve this pressure, then it would appear that he should do a head job. I believe that the inside of the rocker covers are vented to the engine case through the push-rod tubes. As we all know, the case vents in the primary case. If this is so, then the vent from the covers to the carb filter is not necessary. IMHO

[panfreak]

I agree with everything you said, don't get me wrong here. I just thought it was a bit strange that he would have hacked up his pan tops (among other things) and declared his desire to lower oil pressure to avoid leaks. Sad, really, to see so much bastardizing of an otherwise rare and cool bike.

[Kuda]

Plumbing the motor into a slight vacuum source (we used to use dump tubes cut at a 45 degree angle welded into the header collectors, but you could also plumb into the intake or backing plate) can help keep the seals in good shape. The theory is by having the whole crankcase at a slight vacuum keeps negative pressure on the seals, stopping pressure from blowing the seals out. The pressure can come from either a worn motor OR by running really hard/high RPMs. Worked pretty good, actually...

-Kuda (former drag racer)
'49 FL
'00 FXDWG