I’ve removed the airbox, transmission, clutch and flywheel to gain access to the rear main seal so I can replace it. You can see how I did that work here.

• 13 BMW 1983 R80ST Remove Air Box & Pulse Air System
• 23 BMW 1983 R80ST Remove Transmission
• 21 BMW 1983 R80ST Remove Clutch
• 11 BMW 1983 R80ST Remove Flywheel

I’ve published documents on replacing the rear main seal on other projects. Here are links to those documents.

• 11 BMW 1983 R100RS Remove Flywheel & Rear Main Seal
• 11 BMW 1983 R100RS Install Rear Main Seal, Oil Pump Cover & O-ring
• 11 BMW 1977 R100RS Replace Rear Main Seal & Oil Pump Cover O-Ring
• 11 BMW 1975 R75/6 Replace Crankshaft Rear Oil Seal, Oil Pump Cover & O-ring
• 11 BMW 1973 R75/5 Remove & Install Flywheel, Replace Rear Main Seal, Oil Pump Cover & Cover O-Ring

Since the 1983 R80ST engine is similar in many ways to the 1983 R100RS, I link to the 1983 R100RS documents as appropriate in this document.

• 11 BMW 1983 R80ST Replace Rear Main Seal

And here is a short YouTube video showing the procedure.

VIDEO: 1983 BMW R80ST Replace Rear Main Seal

I had a real problem removing the seal on this bike using my usual approach with the Cycle Works rear main seal tool, and had to resort to using “a bigger hammer”. I used a hook seal puller to pry the old rear main seal out of the bore. Since the bike has been sitting for 25-30 years, the seal was really stuck in the bore.

Cycle Works Rear Main Seal Tool

Using Hook Seal Puller To Remove Rear Main Seal

Using Flashlight To Verify Seal Is Flush With Case

I’ve removed the airbox, transmission, clutch and flywheel to gain access to the oil pump. You can see how I did that work here.

• 13 BMW 1983 R80ST Remove Air Box & Pulse Air System
• 23 BMW 1983 R80ST Remove Transmission
• 21 BMW 1983 R80ST Remove Clutch
• 11 BMW 1983 R80ST Remove Flywheel

I’ve published documents on removing, inspecting and installing the oil pump on other projects. Here are links to those documents.

• 11 BMW 1977 R100RS Replace Rear Main Seal & Oil Pump Cover O-Ring
• 11 BMW 1983 R100RS Remove & Inspect Oil Pump
• 11 BMW 1983 R100RS Install Rear Main Seal, Oil Pump Cover & O-ring

Here is the link to how I do the work on the 1983 R80ST.

• 11 BMW 1983 R80ST Remove, Inspect, Install Oil Pump

And, here is a short video that summarizes how I do this work.

VIDEO: 1983 BMW R80ST Remove And Inspect Oil Pump

Oil Pump Cover Removed

Oil Pump Rotors Marked With “F” For Front Face

Oil Pump Measurements – They Are All Good

Since this project bike was not running when I picked it up and had been sitting outside for awhile, I don’t know what components of the electrical system work. So I remove the starter motor and test it.

What The 1983 R80ST Looked Like When I Found It

Here is the link to the documentation on how I do this work and a short YouTube summary of the process.

• 12 BMW R80ST Remove And Test Starter Motor

VIDEO: 1983 BMW R80ST Remove And Test Starter Motor

The good news is the starter motor was in good condition and worked correctly. 🙂  I cleaned up the starter motor and the top engine compartment it sits in.

Starter Motor Nose Refinished

Front Starter Motor Bracket Refinished

Top Engine Housing Is Clean

As I plan to replace the rear main seal, that is the rear oil seal on the crankshaft, inspect the oil pump and replace the oil pump cover O-ring, I need to remove the flywheel. On 1981 model year (the 1981 model year started in September 1980) and later models, the flywheel is also called the “Clutch Housing”, (part# 21 21 1 338 722).

I previously removed the airbox, transmission and the clutch so I can access the flywheel. You can see how I do that work here.

• 13 BMW 1983 R80ST Remove Air Box & Pulse Air System
• 23 BMW 1983 R80ST Remove Transmission
• 21 BMW 1983 R80ST Remove Clutch

The flywheel on the 1981 and later models (the 1981 model year started in September 1980) is different from the earlier models. It is lighter, for one thing and is mounted differently on the rear nose of the crankshaft. The procedure for removing the earlier flywheels (before September 1980) is different as shown in these documents.

• Remove the Flywheel (1977 R100RS)
• Remove the Flywheel (1973 R75/5)

The flywheel on the 1983 R80ST is the same as the one on the 1983 R100RS. I show how I removed the R100RS flywheel here. I’ll link to sections of this document as appropriate.

• 11 BMW 1983 R100RS Remove Flywheel & Rear Main Seal

Here is a link to a document showing how I do this work and a video summary.

• 11 BMW 1983 R80ST Remove Flywheel

VIDEO: 1983 BMW R80ST Remove Flywheel

Air Impact Wrench With 19 mm Socket

Flywheel Bolts Cover Plater

Flywheel Removed With Guide Ring Still On The Rear Nose Of The Crankshaft

Nipple On Front Of Guide Ring And Groove Worn By Rear Main Seal

The clutch in this 1983 R80ST is the same as the one used in the 1983 R100RS that I rebuilt and converted to an RT model. You can see the procedure I used to remove the 1983 R100RS clutch here.

• 21 BMW 1983 R100RS Remove Clutch

R80ST Clutch Assembly

I summarize what I found on the 1993 R80ST in this document, which has links to sections of the 1983 R100RS clutch removal document.

• 21 BMW R80ST Remove Clutch

I also shot a short video of the work I did on the R80ST.

VIDEO: 1983 BMW R80ST Clutch Removal

The clutch was a bit rusty and grungy. I plan to replace it with one donated by Euro MotoElectrics.

Clutch Condition-Rear Side That Faces You

Clutch Condition-Engine Side That Faces Flywheel