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Main seal?

The place to discuss the R 90 S as well as the R90S Worldnet archives!
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srankin
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Re: Main seal?

Post by srankin »

Some airheads have a tendency to smoke if the side stand is used and they sit for a bit. A tiny bit of smoke that goes away fairly quickly is not a problem. LOL, finding someone to ride behind me to look for smoke is the problem.

I will see about snapping some shots of the project. I have two pictures of the bike intact showing the pretty paint job the second owner had done. Sort of like putting lipstick on a pig. But hey, the bike wasn't mine at the time. St.
20241203_175620.jpg
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Owner of a 84, R80RT and 79 R100RT being stripped naked for summer, turned Into a frame up restoration,

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srankin
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Re: Main seal?

Post by srankin »

Here are some closer pictures after starting the restore. St.
20241215_123643.jpg
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Owner of a 84, R80RT and 79 R100RT being stripped naked for summer, turned Into a frame up restoration,

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San Arthur
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Oil Pickup

Post by San Arthur »

The Dipstick and the Oil Pickup: A Subtle Relationship


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If you’ve ever wondered just how close the dipstick’s minimum mark is to the oil pickup, here’s a little detail to consider.


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With the sump off, you’ll see the oil pickup sitting just below where the dipstick reaches—about 1 cm beneath the minimum line.

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It’s a small margin, but it speaks volumes about why keeping the oil level in range matters. Drop below minimum, and you’re flirting with oil starvation under hard acceleration, braking, or in the twisties. The pickup simply won’t have enough to work with.

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A full sump isn’t just a matter of routine—it’s peace of mind for these engines you know well.
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

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San Arthur
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Re: Main seal?

Post by San Arthur »

srankin wrote:
Sun Dec 15, 2024 4:22 pm
Here are some closer pictures after starting the restore.
St. Do you have pictures of the frame after restoration?
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

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srankin
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Re: Main seal?

Post by srankin »

Interesting pictures, and a good point.

I have just started the process, the back half of the frame, fender swing arm is out. I really need to take the faring off before I go any further. St.
Owner of a 84, R80RT and 79 R100RT being stripped naked for summer, turned Into a frame up restoration,

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San Arthur
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First Pass at Cleaning Cylinder Head Fins

Post by San Arthur »

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Started cleaning the head fins with a fiber pad and concentrated Simple Green to break through the initial grime. This is just the first step—I’ll go deeper in the next round.

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Any tips for deeper cleaning while preserving the finish?
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

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srankin
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Re: Main seal?

Post by srankin »

I have a ton of engine case and other parts in dire need of cleaning. Your stuff is looking pretty good so far. St.
Owner of a 84, R80RT and 79 R100RT being stripped naked for summer, turned Into a frame up restoration,

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San Arthur
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Timing Cover and Chain Replacement Progress

Post by San Arthur »

I’ve been working on my R90S, removing the timing cover and inspecting the timing chain for wear. Here’s an update on what I’ve found and what I plan to do:

Timing Cover Removal

To remove the timing cover, I used a torch to carefully heat the area around the shaft bearing. This caused the aluminum to expand, making it much easier to remove without damaging the bearing or the cover. This method worked great, and the cover came off smoothly.


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Chain Tensioner and Timing Chain Condition

Upon inspection, the chain tensioner shows visible grooves from prolonged use. It’s definitely time for a replacement.


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The chain itself appears to be the original endless-style chain (no master link) and has noticeable slack.




It’s likely stretched from years of use, so I’ll be replacing it along with the tensioner and spring.

• I’m carefully cleaning off the old gasket material from the timing cover to ensure a good seal when reassembling. A razor blade and patience are key here—don’t gouge the aluminum!

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Last edited by San Arthur on Mon Jan 20, 2025 6:39 pm, edited 1 time in total.
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

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srankin
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Re: Main seal?

Post by srankin »

Boy, your stuff looks a lot cleaner to start with than mine does. LOL, I have been soaking the transmission in degreaser and still am scrubbing off crud. St.
Owner of a 84, R80RT and 79 R100RT being stripped naked for summer, turned Into a frame up restoration,

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San Arthur
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Flywheel Removed and Observations

Post by San Arthur »

Hey everyone,

I finally managed to remove the flywheel. Here’s a quick rundown of what I did and what I found:
1. Process:
• Secured the crankshaft to prevent any movement.
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• Used the appropriate flywheel removal tool to unbolt it.
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2. Observations:
• I noticed a small amount of oil seeping from the main seal. However, the oil pump cover also looks quite oily, so I suspect it may be contributing to the leak.

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• The oil pump cover on my bike has bolts instead of the original Phillips screws. Could these have been changed after 1975, or did someone modify this before?
• I forgot to order the flywheel O-ring. Rookie mistake, I know, but it’s on my to-do list now.
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3. Flywheel Condition:
• The teeth on the flywheel are in better shape than I expected. No major wear or damage.

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• I think I figured out the TDC marking issue. When I align the flywheel as it was installed (first picture),
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the marking doesn’t make sense. If I rotate it two bolts to the left, the “OT” mark aligns correctly. It looks like the flywheel was misinstalled by a previous owner or mechanic.
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Has anyone else encountered a misinstalled flywheel like this before?

Appreciate any advice or tips!

Cheers
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

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