Exposing Oil Picc-up On Steep Grades

[Thunderpaugh]

I would like to hear comments and technical opinions about the possibility of exposing the oil pick-up while assending a steep grade. Assume that the oil level in the crankcase is at the high mark on the dipstick with the dipstick screwed in and the bike on level ground and upright. What degree of grade would cause the oil pick-up to be exposed and result in the loss of oil pressure?

[Pierre]

I would like to hear comments and technical opinions about the possibility of exposing the oil pick-up while assending a steep grade. Assume that the oil level in the crankcase is at the high mark on the dipstick with the dipstick screwed in and the bike on level ground and upright. What degree of grade would cause the oil pick-up to be exposed and result in the loss of oil pressure?

If you find a grade that steep, you'd better have knobbies mounted.

[Guest ratchethack]

I would like to hear comments and technical opinions about the possibility of exposing the oil pick-up while assending a steep grade. Assume that the oil level in the crankcase is at the high mark on the dipstick with the dipstick screwed in and the bike on level ground and upright. What degree of grade would cause the oil pick-up to be exposed and result in the loss of oil pressure?

Well, since it's easy enough to expose the pickup on flat and level ground, I reckon any kind of uphill makes it all that much easier. As far as what degree grade would cause it? How about any degree a-tall, relative to how hard you accelerate -- even a downhill grade -- the steeper (in an uphill direction), the more exposure, earlier, and for longer duration the exposure's likely to be?

[pete roper]

Yup, it's possible and in many cases quite easy. The oil pick up is in the front right hand (? this is from memory at 4.30AM.) corner of the sump. Uphill and banking to the left is the most risky. It's a problem that Guzzi finally, obliquely, acknowledged with the launch of the Breva/Griso/Norge motors which have a far better sump design.

 

Yes, there is a cure, but since I'm the one that designed it I always get accused of venal motives and charlatanry when I mention it.

 

Pete

[Greg Field]

Pete actually has two venal solutions. First, always fill the sump with Roper Ranches ® Genuine Yak Fat ™. Second, fit a Roper Slopper.

[Pierre]

Yup, it's possible and in many cases quite easy. The oil pick up is in the front right hand (? this is from memory at 4.30AM.) corner of the sump. Uphill and banking to the left is the most risky. It's a problem that Guzzi finally, obliquely, acknowledged with the launch of the Breva/Griso/Norge motors which have a far better sump design.

 

Yes, there is a cure, but since I'm the one that designed it I always get accused of venal motives and charlatanry when I mention it.

 

Pete

Pete, banking has zero effect on oil position in the sump. His question regarded a grade steep enough to expose the oil pick up. You guys are waaaay out in left field encouraging his paranoia.

[Guest ratchethack]

Pete, banking has zero effect on oil position in the sump.

I'm sure Pete will re-think this one and agree.

[Thunderpaugh]

Well, since it's well possible to expose the pickup on flat and level ground, I reckon on any kind of uphill makes it all that much easier. As far as what degree grade would cause it? How about any degree a-tall, relative to how hard you accelerate -- even a downhill grade -- the steeper (in a positive direction), the more exposure, earlier and for longer duration the exposure's likely to be?

 

 

How 'bout accending a San Francisco-style grade about 0.1 mile long, with a 1/2 San Francisco style-grade approach about 0.1 mile long @ a steady 30-40 mph (no acceleration).

[Guest ratchethack]

How 'bout accending a San Francisco-style grade about 0.1 mile long, with a 1/2 San Francisco style-grade approach about 0.1 mile long @ a steady 30-40 mph (no acceleration).

Having lived in The City and negotiated lots o' those streets countless times, I'd have a Roper plate in there ASAP or expect to suffer the consequences -- sooner rather than later.

 

But o' course, that's just me, and YMMV.

[pete roper]

How 'bout accending a San Francisco-style grade about 0.1 mile long, with a 1/2 San Francisco style-grade approach about 0.1 mile long @ a steady 30-40 mph (no acceleration).

 

I dunno for sure how steep it would have to be to expose the pick up. If you're getting to the point where its that steep the rear crank web will be throwing a lot of the rearward settled oil about anyway further diminishing that sitting near the front of the sump where the pick-up is. Do remember that the plate DOES have holes in so the oil WILL still migrate rearwards. It's purpose is to slow the rearward movement sufficiently that pick-up exposure doesn't occur in hard acceleration situations be they on a flat surface or a hill.

 

The fact that the plate DOES do this has been independently verified by Greg who gave his bike, which used to regularly expose its pick up, the 'Torture Test' he described in his installation write up. Up a steep cobbled street in Seattle, hard on the gas, and no pressure drop I really don't know what I can do to further prove my point. Individual evaluation by a third peer party or parties and repeatable results achieved under a variety of conditions would seem like pretty good scientific evidence and proof to me but obviously I have a hidden agenda and have nothing better to do with my life than deliberately try to make people paranoid about non existant problems.

 

Can I categorically say that in the conditions you've described above there will or won't be pick up exposure? No, I can't. But knowing what I do about the exposure problem I would think that living in that sort of environment is exactly the sort of place where it could be a problem, if not in this exact circumstance then at least on a regular basis.

 

Pete

[Ryland3210]

Add my name to the list of advocates. Without Pete's sloppage plate, oil pressure dropped precipitously at 4000-4500 RPM under max. acceleration in first gear on level ground with a rolling start (no wheelie), with 4 quarts of oil. Under the same conditions with the Roper plate, I could not make the pump starve.

 

There is ample hard data to support the existence of the problem, and the fact that Pete's plate cures it, certainly level ground.

 

On the question of how steep a grade would cause pump starvation, one could use dyno measurements to calculate the equivalent grade to first gear max. accels (which caused pump starvation), and second gear (which did not).

 

Having said that, as the grade increases, how much acceleration would it take to cause starvation? Fuggeddaboudit! Go with Ratch's advice and install a Roper plate! Then refill with 4.5 quarts (just below his plate, with filter change).

[Troy]

I'm sure Pete will re-think this one and agree.

 

 

 

 

I see what you two are saying in that once you are into a turn, the oil surface stays flat with the sump. But If you countersteer hard to initiate a left turn won't the oil momentarily try to stay on the left side of the sump?

I think Pete has a point.

[Greg Field]

Pete, banking has zero effect on oil position in the sump.

 

At zero speed or low radial acceleration, it sure as hell does. Toss you bike on its side and start it up. See that I speak the truth.

[Pierre]

At zero speed or low radial acceleration, it sure as hell does. Toss you bike on its side and start it up. See that I speak the truth.

Truth perhaps, but in the context of this discussion you've managed to nimbly sidestep the sublime and jump straight to the absurd. Not that there's anything wrong with that, of course. Just sayin'.

 

Sheesh. You'd think it was the first of April around here.

[Greg Field]

OK, then, pretend you're a squid accelerating hard from low speed with the bars at full lock. You could be turning accelerating hard to the left, with the bike upright or even leaned slightly to the right, and all that erl slopping to the outside.