Semi-restoring a 1978; Need advice about best sequence? (long)

[Kurt in S.A.]

On my /7, I remove the rubber plug and nut/washer. Then with an allen wrench, I push the end of the threaded rod upwards inside the slider...oil begins to drain. When finished, I wiggle the allen wrench to get the threaded rod to expose itself again and put on the nut/washer.

Kurt

[R100SinLA]

[quote=R100SinLA post_id=135701 time=<a href="tel:1717449541">1717449541</a> user_id=13154]
Hi folks
1st post … some photos attached below

Background about this motorcycle:
1978 BMW R100S
Matching numbers
Factory production date 12/1977 According to info found online
Odometer approx 15,000 miles believed to be true
Purchase: 11/2023 locally (Los Angeles) from second owner. (No service documentation supplied). Seller says he purchased from original owner In SoCal in 2021 or so.

Appears to be true low miles bike (15k)
Appears to be factory/stock mechanically except:
Boyer Bransden electronic ignition system installed by a previous owner probably decades ago (BMW - Type MK 3)

I have not touched/adjusted carbs since acquisition…seller said he went to local airhead ‘guru’ for carb adjustments…

Current status:
Runs pretty well
throttle feels subpar
idles ok but only after completely warmed up (1300-1400 at idle according to tach)…yes it’s probably too high.
Handling is good so far…under 60 mph only.

So, I’m about to start the following work and have all parts/materials ready to go:

-not in any particular order-

Check/adjust timing
Check/adjust valve clearances and rocker arm end play
Check for air leaks all around carbs (spray brake cleaner test)
Install new (correct??) spark plugs- BOSCH W5DC (currently NGK BP6ES)
Install new (stock BMW) plug wires
Service/lube throttle control
Install new (stock BMW) throttle cables
Install new (stock BMW) choke cables, service choke lever (airbox mounted)
Disassemble/complete rebuild Bing 40 carbs (all parts from BMW)
Synchronizing carbs

So here’s my problem/question:
Seeking advice as to the best sequence of the above tasks.

My main concern is making sure I have a decently running bike to take those required 5-10 mile warm-up runs prior to some of the tasks. (Will be first time working on Bing carbs)

Have been studying/following Snowbum’s writings diligently (Thank you Snowbum!!)
And also William’s videos from Boxer2valve (Thanks William!!)


MORE INFO:

Work completed by me since acquisition (11/2023):
1. All fluids changed including fork oil
2. Sump pan removed, cleaned and new gasket/bolts installed
3. Air filter (mahle) installed
4. Front brake system (dual disc) serviced/rebuilt including new rubber hoses, MC & calipers rebuilt
5. Front forks serviced (rebuilt) & new factory springs
6. Dual horn system installed, including new harness/ relay/ fuse
7. Factory “S” fairing, nice condition (sourced, previously painted black) installed, factory volt gauge & clock (like new) sourced, & custom (by me) quick-disconnect harness with connector
8. Installed front turn signals/correct wiring
9. All new bulbs installed (except not inside instrument cluster)
10. New fuses installed in headlight bucket
11. Sorted/checked connections in headlight bucket
12. All known grounding connections on frame sanded cleaned up
13. New starter relay & new voltage regulator installed
14. Many assorted rubber bits/grommets/washers/bumpers/rings/etc replaced
15. Luggage mounts (Reynolds) installed
16. New gloss black paint work by outside shop (tank, seat, fr fender & side covers)

Cheers
JC

image2.jpeg

image3.jpeg

image1.jpeg

Thats a nice looking bike, looks like your doing what I did to my 1978 R80/7, seems I have done what you have planned but in my case I had to remove both pots and replace the pushrod tubes with S/S Items as mine were either loose or had rotted through.

I still have to pull my front forks off again as I put the wrong weight oil in last time, I now have the BMW fork oil to cure the issue with a stiff front end.

Good luck with the rebuild.
[/quote]


Thank you.

Funny you should mention the pushrods…
Since my original post I have decided to just get more done using the “while I’m there” logic.
I have a couple of small leaks.

So added to the list: a top end reseal.
and I’m pulling transmission, clutch and flywheel. Doing Rear main seal and some o -rings. Also spline service and some related seals… and new clutch cable.

Ordering all needed supplies/ tools/ parts

Although once I do the leak down I know a lot more.

Also, I agree with the others
Assuming your ‘78 is similar to my ‘78
There is a drainage method for the forks
As well a filling method so you shouldn’t have to mess with big top nuts…


Anyway, for your entertainment,
Adding a couple of pics from the day of purchase (6 months ago) while deciding to buy or not..

Yes both pics are of the same bike… taken at the same…it had some paint issues

[melville]

I like the red detail on the brake disc carriers! I might do something like that with blue on my RS project.

[jackonz]

[quote=R100SinLA post_id=135701 time=<a href="tel:1717449541">1717449541</a> user_id=13154]
Hi folks
1st post … some photos attached below

Background about this motorcycle:
1978 BMW R100S
Matching numbers
Factory production date 12/1977 According to info found online
Odometer approx 15,000 miles believed to be true
Purchase: 11/2023 locally (Los Angeles) from second owner. (No service documentation supplied). Seller says he purchased from original owner In SoCal in 2021 or so.

Appears to be true low miles bike (15k)
Appears to be factory/stock mechanically except:
Boyer Bransden electronic ignition system installed by a previous owner probably decades ago (BMW - Type MK 3)

I have not touched/adjusted carbs since acquisition…seller said he went to local airhead ‘guru’ for carb adjustments…

Current status:
Runs pretty well
throttle feels subpar
idles ok but only after completely warmed up (1300-1400 at idle according to tach)…yes it’s probably too high.
Handling is good so far…under 60 mph only.

So, I’m about to start the following work and have all parts/materials ready to go:

-not in any particular order-

Check/adjust timing
Check/adjust valve clearances and rocker arm end play
Check for air leaks all around carbs (spray brake cleaner test)
Install new (correct??) spark plugs- BOSCH W5DC (currently NGK BP6ES)
Install new (stock BMW) plug wires
Service/lube throttle control
Install new (stock BMW) throttle cables
Install new (stock BMW) choke cables, service choke lever (airbox mounted)
Disassemble/complete rebuild Bing 40 carbs (all parts from BMW)
Synchronizing carbs

So here’s my problem/question:
Seeking advice as to the best sequence of the above tasks.

My main concern is making sure I have a decently running bike to take those required 5-10 mile warm-up runs prior to some of the tasks. (Will be first time working on Bing carbs)

Have been studying/following Snowbum’s writings diligently (Thank you Snowbum!!)
And also William’s videos from Boxer2valve (Thanks William!!)


MORE INFO:

Work completed by me since acquisition (11/2023):
1. All fluids changed including fork oil
2. Sump pan removed, cleaned and new gasket/bolts installed
3. Air filter (mahle) installed
4. Front brake system (dual disc) serviced/rebuilt including new rubber hoses, MC & calipers rebuilt
5. Front forks serviced (rebuilt) & new factory springs
6. Dual horn system installed, including new harness/ relay/ fuse
7. Factory “S” fairing, nice condition (sourced, previously painted black) installed, factory volt gauge & clock (like new) sourced, & custom (by me) quick-disconnect harness with connector
8. Installed front turn signals/correct wiring
9. All new bulbs installed (except not inside instrument cluster)
10. New fuses installed in headlight bucket
11. Sorted/checked connections in headlight bucket
12. All known grounding connections on frame sanded cleaned up
13. New starter relay & new voltage regulator installed
14. Many assorted rubber bits/grommets/washers/bumpers/rings/etc replaced
15. Luggage mounts (Reynolds) installed
16. New gloss black paint work by outside shop (tank, seat, fr fender & side covers)

Cheers
JC

image2.jpeg

image3.jpeg

image1.jpeg

Thats a nice looking bike, looks like your doing what I did to my 1978 R80/7, seems I have done what you have planned but in my case I had to remove both pots and replace the pushrod tubes with S/S Items as mine were either loose or had rotted through.

I still have to pull my front forks off again as I put the wrong weight oil in last time, I now have the BMW fork oil to cure the issue with a stiff front end.

Good luck with the rebuild.

Thank you.

Funny you should mention the pushrods…
Since my original post I have decided to just get more done using the “while I’m there” logic.
I have a couple of small leaks.

So added to the list: a top end reseal.
and I’m pulling transmission, clutch and flywheel. Doing Rear main seal and some o -rings. Also spline service and some related seals… and new clutch cable.

Ordering all needed supplies/ tools/ parts

Although once I do the leak down I know a lot more.

Also, I agree with the others
Assuming your ‘78 is similar to my ‘78
There is a drainage method for the forks
As well a filling method so you shouldn’t have to mess with big top nuts…


Anyway, for your entertainment,
Adding a couple of pics from the day of purchase (6 months ago) while deciding to buy or not..

Yes both pics are of the same bike… taken at the same…it had some paint issues
[/quote]
Mechanically my motor was brilliant with good compression and it was a runner although it needed a tune up and the carbs cleaned, it has Boyer Electronic ignition so I don't have to worry about the points.
Main issue for mine was oil leaks, sump pushrod tubes and rear main seal and a slipping clutch, the clutch problem was due to the rear main oil seal leak and I ended up having to do it twice, the first seal I purchased was not a genuine BMW seal but a pattern item and after only 150 miles it leaked, so I ended up getting the OEM seal from BMW and no issues since.

Withe the motor top end as the bike has only 45,000 miles on the clock (verified) it was in first class condition valve guides valves and pistons and bores all good, so all I needed was to clean up the corrosion on the outside of the cylinders and heads so I stripped it all down and in work we have a blasting cabinet and it all looks like new now.

I still have to replace the rear shock absorbers (Going to Hagon) and re spoke the front wheel although not urgent.

The paint on mine with the tank and front guard was awful, it was so faded and chipped and was the brown shit colour all repainted to a nice silver now.

Good Luck.