Capo,
Don't let my little comment worry you, installing a Baisley spring is highly unlikely to increase pressure and flow to the point of causing any damage. I just throw that comment out for that group of people who really do believe if a little bit is good, a whole lot must be better. Trust me, they are out there. Assuming the learned folks on this site know better than to fire up a cold engine and immediately ride off at high rpm, a 15 psi increase in bypass valve setting isn't going to cause seal failures and leaks.
One area with a Harley that I would be concerned about is oil carryover or blow-by, due to the marginal design of the breather system. If someone already has problems with excessive oil in the air cleaner, jacking up the oil pressure and flow is only going to make it worse. The oil system is designed as a whole, with the oil passages, drain back passages, and air/oil separators sized to work with a particular viscosity of oil at a particular flow rate. As is true of most engineered products, changing just one of the many variables seldom results in a total win/win. If a simple change to the stock spring tension was the cure-all that many seem to profess, why would H-D not specify a higher tension spring in production? Wouldn't add any cost, and would help meet sound emissions rules. Hmmmmmmm. 
Jerry
Don't mean to start a major debate, but I have some questions.
Over the years I've been dealing with motors, going back to VW buggies, streetrods etc. I know that you can raise the upper limit to which an oil pump will produce more and more pressure; the spring is a quick way to do this. But oil pressure is limited to the rpms the pump is turning. So in theory the stiffer spring would have no affect on idle or cruising pressure, just WOT pressure. Oil pumps are a positive displacement pump and produce the same output volume per revolution of the pump; more revs, more oil until they hit their maximum pop off or bypass pressure.
Pressure is also relative. It really depends on what your particular motor clearances are. In a tight motor, tight clearances, if fed with a known quality pump, the pressure will be higher than the same pump in a worn out, or looser clearanced, motor. Tighter has more resistance to being fed through the motor and looser spills oil out all over the place reducing the pressure required to move the oil through the motor. Again I believe rpms is still going to be a factor in oil pressure.
The gearotor type pump that HD uses on the twin cams is more efficient than the older twin opposing gear type, but both types are still driven by rpms.
I just find it hard to understand the advantage of the heavier pressure spring if you're not at maximum rpms and at the upper limits of the oil pump. If maximum pressure is designed to max out at 2,500 rpms, then probably the heavier spring pressure on the bypass ball will help produce more oil flow and more oil pressure. If the oil pump is truly linear and doesn't max out until 5,000 rpms, the spring in my opinion is just a wasted effort and a few bucks gone.
Oil viscosity will play a big part in oil pressure as some have already mentioned. I tried several different types of dino oil and synthetics in my blown 392 hemi in my streetrod and found Mobil 1 to be the best for pressure over all and oil temps.
I've had my 1,000 mile first service at the dealership and I had them use their Syn3 as originally installed. I'll be changing out my own oil from now on and will be switching to Mobil 1 V-Twin oil. Ever since my '08 SERK was new, now about 2,100 miles, it has had the slight ticking noise from 2,500 rpms to about 3,100 rpms. This may be what some are calling sewing machine noises. It doesn't matter what gear I'm in, just when the rpms are right it let's loose with the ticking; under load or coasting is no different. Some have said theirs did this and after a bit it should quiet down, but mine is still ticking away. I think more oil pressure would help, but without changing the volume the pump puts out at any given rpm, I'm stuck with what I have. Maybe the switch to the other oil will help; don't know though.
Does any of the above make sense to you guys?
Thanks for listening to my ramblings.
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Topic: Oil Pressure when riding? (Read 7338 times)