Deep Oil Sump?

[Manfred]

I have a 1987 R80RT with no oil cooler, living in south Texas. Mac Performance sells a deep sump for '69 - '89 airheads that adds 2 quarts to oil capacity. http://www.macperformance.com/store/pro ... ct_ID=1256 Does this seem like a good thing to add to my bike?

[vanzen]

IMO:
The best function of a deep sump will be it's ability to decrease crankcase pressures at higher rpm
by using the same, as stock, quantity of oil ... not more.
Having said that, 2 extra quarts sloshing about should help to reduce temps ... some ... maybe ...

[Garnet]

At the risk of starting an oil thread, motor oil has come a looooong way since our bikes were built. Even inexpensive oil has the ability to maintain viscosity at much higher temps. If you are terribly concerned, just change it more often.

BTW, does the R80 use the same sump as the R100 of that year. If so,you will only add about 1/2 quart with the pan you are looking at.

[Manfred]

I am familiar with the oil issues

The RT100RT and R80RT of 1987 use the same P/N for the oil pan - I don't see how one would mean 1/2 quart more oil for the Mac Perf pan. They claim that pan holds 2 qts more than the stock pan - I've asked them for the vertical dimension so I can figure out how low it would hang.

How do you figure it would only hold 1/2 qt more?

[Garnet]

Find out how much the Mac pan will hold. Your pan should holds around 3 quarts. A /5 and early /6s held 2 quarts. Since they advertize that pan as fitting all airheads, perhaps it holds 4 quarts which is 2 more than the early models.

I had a very simialer pan to the Mac on my /7 and it only held 3 liters, which is about 3.2 quarts.

[Manfred]

Garnet,

Would you "do it again" - put a slightly larger oil pan on your bike?

[Garnet]

Garnet,

Would you "do it again" - put a slightly larger oil pan on your bike?

No I would not. I put that "other" pan on in 1978 following the "more is better" theory. I now have a pair of 750s now and live in the PNW and feel no need what so ever to change.

That being said I do have a late model stock R100 pan. It will go on one of my bikes when I figure out how to use the R100 cylinders I have. The reasoning follows what Vanzen stated above, lowering the oil level allows more crankase volume and helps reduce oil misting and blowby.

[Zombie Master]

Ground clearance.

[Garnet]

One more comment on the Mac style of pan.

With the pan that I had (not Mac), when I ran the stock amount of oil, the oil light would flicker under hard braking. As a reault I allways ran the oil level at the full mark on the dipstick, which meant I gained no crankcase volume.

[melville]

My oil pan looks to be a Mac, and with three full quarts the dipstick reads halfway between "full" and "add a quart." Bike is 1975 R75/6, dipstick appears to be stock.