Any 91 and up oil pump will bolt to a 77-90 case and is considered an upgrade.
However, the 07 and up pump has the largest scavenger gerotors to move the most oil back into the oil tank.
5)
The oil pump acts as a pass through for the filter return line. 6)
Since XL motors just flood the motor with oil, the issue is on the scavenging side (trying to get the oil back out of the motor).
Hence the trend toward bigger scavenging sections and smaller pressure sections.
Many racers actually reduce their oil pressure trying to solve scavenge issues.
The last thing in the world you want to do is pump more oil into an XL engine. 7)
The line returning from the oil filter pad feeds oil into the bottom of the cam box. 8)
From there oil goes up through the cover, oiling the pinion, lower end, as well as going up to the lifters and valvetrain.
The oiling system changes that came with the introduction of rubber mounts were a huge step backwards.
There are a lot fewer problems with the 2008 and later bikes judging from previous years as they have they updated rocker boxes and breathers.
The oil pump is not the end all fix though.
On the 06 and Earlier bikes, just changing the oil pump was not the step that suddenly made the blow-by disappear.
Neither was correcting the ring end gap. 9)
You know what's ironic? The better the ring seal, the worse the problems with XL oiling are.
A little crankcase pressure actually helps the scavenging.
We saw it a LOT when using gapless rings. It just plays hell with the oiling. 10)
The 07 and up style pumps are a great upgrade to an 86-90 engine.
They made the scavenge section bigger and the pressure section smaller. 11)
The 5-speed to 4-speed conversion is not a hard mod to accomplish. 12)
However, I would not put it on hoping it'll solve a wet sumping issue.
Wet sumping is more of a crankcase pressure issue in my experience.
I've never had any luck curing a wet sumping issue by changing the pump.
Specifically, the 2007 Buell and XL style oil pumps have the bigger and better scavenge gerotors.
It gets a little tight right there where the line from the oil filter pad feeds into the bottom of the cases.
Between the return line fitting on the pump and the feed line into the motor, the pump tries to hit the return line fitting on the pump.
(the feed line into the motor will normally be coming from the oil filter pad).
That's the only tight spot, the newer oil pump bolts right up otherwise. But, with a little grinding, it can be done. 13)
1998 and up oil pumps will bolt straight up to 77 -97 engines.
However, 1977-1997 engines drain the cam chest to the crankcase.
1998 and later pumps all have a scavenge inlet in the cam box and therefore your motor's cam box to crankcase drain is not needed and actually not desirable. 14)
So a complete update would include plugging that drain.
The '07 Buell pump has a bigger scavenge section than the standard Pro-Flow.
Unless you go to a multi-section Pro-Flow and all the associated plumbing, you're better off with the 07 pump.
15) 16)
There is also another option of modding the oil pump cam drain port instead.
The cam port on the pump is blocked off.
Currently the only known company that does this mod is Karling Racing in Sweden.
See more on the Karling Oil Pump Mod for the newer oil pumps here in the Sportsterpedia.
1986-1990 model engines are fed oil internally; oil pump → filter → oil pump → gearcase inlet hole.
1991 and up engines are fed oil externally straight from the filter pad so you'll have to adapt them for earlier 4 speeds.
When you take off the stock pump, it will expose a 1/8“ hole in the bottom of the gear case. 17) 18)
This is the oil's internal point of entry from the pump and where the 90° fitting goes.
91 and up engine cases do not have this hole.
86-90 oil port location (app. dims) 19) |
Oil entrance hole tapped with a 90° fitting installed 20) |
26204-91A oil pump hardware kit. Fits 98 and up oil pumps & 77 and up engines (w / 1998 up pumps). 34) |
The pump to engine mounting holes will match up, you just have to tap the case for a 90° fitting.
The conversion mod can be done with the engine in or out the frame.
You'll need to drill the existing 1/4” oil port in the bottom of the case to 11/32“ and tap it for 1/8” NPT pipe threads.
(Pre-drill size letter “R” or 11/32“)
Obviously, this would be the easiest way to drill and tap the hole,
It'll keep the process from being awkward and allow you more control of the process.
The hole can then be drilled / tapped by hand or in a drill press.
With the rocker boxes off, you may be able to reposition, without removing, the engine to get the pump area away from the frame.
You can pull the mounting bolts, block up the right side of the engine with 2x4s to drill / tap the hole and bolt it back in when done.
The maximum area available between the engine case and the frame is app. 2.75”. 38)
Drilling:
Tapping:
Tap the oil galley for the 1/8”-27 fitting for the 07 pump.
Before installing the oil pump,
It'd be a good idea to check the condition of the oil pump drive gear on the pinion shaft for wear.
See also Known Drive Gear Failure and the Bronze Oil Pump Drive Gear Upgrade in the Evo oiling section of the Sportsterpedia.
Check the mounting bolt lengths. The OEM bolts only have to extend into the engine flush with the inside hole.
You can also buy grade 8's or stainless from most hardware stores and cut them to length if needed.
With the newer pump being more slim in design and the mounting holes through the pump being a slightly smaller I.D.;
You have a slight fudge factor in positioning the pump before tightening if needed.
Install the hoses in their original locations and you're done.
07 oil pump installed on 89 model engine. Fittings installed. 44) | This is an S&S motor which features 4-speed oiling. Now with a later oil pump and a 90° fitting added. 45) 46) |
Looks nice and tidy. 47) |