In as much as Harley has discontinued Sport Trans Fluid and it's now an obsolete part number I think the only HD product out there is Formula+ for your use.
Yes, Harleys have primaries...
No, the engine oil and trans oil are not fed from the same tank on H.D. bikes. Engine oil is separate, from the primary drive chain on 4 speed big twins, the transmission oil is also separate. Sportster engines have separate engine oil and their transmissions share primary case oil with the wet clutch. 5 speed models wet clutch models have separate primary case lube, transmission lube and engine oil. As far as my memory serves, no Harley Davidsons have shared engine oil and transmission oil similar to some Jap bikes
There is no transmission drain plug. Your transmission uses the same oil from the primary. Draining your primary drains your transmission.
Primary transmission refers to public transmission using signals that are also forwarded for secondary transmission irrespective of location.
Transmission 1qt Primary 1qt
You don't, it uses the same oil as the engine. WHOA! do NOT go by that last answer somebody left. Japanese bikes share the same oil in the engine and transmission. Harleys do NOT share engine oil with the transmission. Tranny oil must be checked and changed separately than from the engine. You must open the derby cover over the clutch to check and add transmission oil on a newer Sportster. Older Ironhead Sportsters have an inspection plug on the primary. have someone hold the bike straight up, you will get a false level on the kickstand. It uses 20-50wt motor oil OR HD primary oil. There's also a chain inside that primary that has to be adjusted regularly. Get a factory service manual.
I have allways used the Formula One primary and transmission oil. Some of my customers say that using a Synthetic oil Quiets the trans. Your choice.
The primary on the HD transfers power from the engine to the transmission.
sportsters do not have a separate transmission, it is actually integrated into the cases and does not have its own oil supply. the oil you put in the primary also works as the transmission lubricant by flowing back and forth from primary to tranny.
On the neck. Where the front end is attached! There is a partial vin (not complete) on the left side of the engine just below the cylinders and just above where the primary bolts on.
removing the starter on all harleys that i am familiar with 60's to present involve removing the primary cover. Thus, i strongly suggest buying a repair manual.
The transmission and crankcase are one piece on a Sportster.