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1973 R75/5 Back-to-road Project

anotherbmw

New member
I had started another thread "1973 R75/5 Restoration" but brought the bike home today and thought to start over with a more detailed description and some pics. Again, the bike seems unmolested, has set for about 10 years but runs. Here is when I brought it home. Everything works, all the dash lights (although the Neutral lost it's green), all blinkers, horn, high beam, etc. I started it up with no problems. The left carb leaks though, so one of my first things to tackle.

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Also included were many spare parts. Bags with rubber bits and pieces, washers, filters, a brand new ignition switch. Luggage rack, back rest, crash bars (brand new!), side cases from a later year I suppose, a spare header since the original has a dent, Vetter fairing with all hardware, spare gaskets and whatever else you can see in the pic. And now the best, original documentation back to the day the bike was bought. A thick folder with notes, maintenance records and receipts.

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It came with what I believe are original tools! The tire irons have BMW stamped on them. All the wrenches have "Made in Germany" on them and some have the "BMW" on there as well. Original owners manual is included as well.
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More pics

Left carb is leaking.

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All dash lights work, but the neutral is white, it looks like there is a little green plastic piece that moved out of place.

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Perfectly straight and rust free rims.

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And even more pics

What do you think about the tank? A bit rusty for my tastes, and there are no fuel filters in the fuel line.

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Congrats Olaf - nice ride - I used POR to recondition tank on my airhead.

You'll more like than likely Ned to buy carb kits from Bing - have you sought out the local airheads club in TX? A great way to learn how to repair, tune and gain appreciation for this wonderful air cooled bike.

Pretty!
 
A very nice example, again, well done. Looks like perhaps the spokes were upgraded to stainless steel as they are bright - often by this time the zinc has washed off the OEM spokes. This would be a bonus.

Carb leak could be the float stuck to the bottom of the bowl in the "open" position. Drop both bowls carefully (held in place by "bales") and check bowl bottoms for any crud, clean with carb cleaner, re-assemble and see if leak stops. I would agree that a near-future carb overhaul would be in order and Bing has the the kits. Lots of help available on the internet for this but it can be a bit daunting if you've never done it before. Also, fuel lines get hard/deteriorate and leak where they attach. If I count correctly, there are 10 such connections (without filters). One or more of those may start leaking soon, or, may be the source of your current leak.
 
Super! The inside of the tank has a red lining that may look like rust. a better test for rust is to stick your finger into the tank and rub it on the inside of the top of the tank. You may feel roughness and pull out your finger with a bit of rust on it. There is a method of removing internal rust without damaging the paint. Spokes look original with a bit of rust starting in the nipple area. Originals are chrome plated. The tool kit bag looks like new! The complete tool kit is pictured in your owners manual. If you can't tell from the picture there are other sources that list exactly what came on the kit. Don't rely on a modern parts book picture such as the one from MAX BMW as a new kit will not have all the original parts. No disrespect for MAX. It's just the parts picture from Germany showing what you get now instead of what you got in 1973.
Although I do recommend going completely through the carbs to replace all the old rubber parts, there is a possible quick fix for the leak. often you can get a piece of dirt lodged in the float needle. If this is the case you can often flush the dirt out by the following method. Turn off the gas tank taps. Remove the float bowl from the leaking side. Turn a gas tap on for a second to let the fuel flow through the float pin orifice. Push up on the float gently to stop the flow. Repeat if necessary then turn off the tank petcock and put the float bowl back on.
 
Kentuvman: Haven't come across the club but will definitely check on it!

ebeeby: I took off the bowl earlier. As clean as it can be inside. Put everything back together and the leak stopped. The only time it leaks now is when the engine is off, bike on the side stand and fuel petcock in the open position. I have done many carb overhauls on my CB 750 and kZ 1000, so I should be fine when tackling the Bings.

1074: I will check the tool kit and great advice on the tank! Will try that out next time in the garage. I was surprised how clean the fuel in the bowl was so maybe you are right and it isn't rust? Do the bikes come without inline fuel filter?

What would be a good way to clean the outside of the engine? I think engine cleaner is a no-no on Aluminum, isn't it?

Again thanks everyone!
 
The only time it leaks now is when the engine is off, bike on the side stand and fuel petcock in the open position.

Well, don't do that anymore! :stick Actually, extended time on the side stand does cause a slight lean to that side and the result is that the float might not move up/down as easily. Also, IMO you should always turn off the petcock when you're off the bike. It's such a habit with me...engine off, petcocks off. Not to mention, if gas continues to flow into the downhill cylinder and the intake valve is open, you can get fuel either into the oil and/or fluid will fill the combustion chamber and you'll do engine damage the next time you hit the starter button.
 
Well, don't do that anymore! :stick Actually, extended time on the side stand does cause a slight lean to that side and the result is that the float might not move up/down as easily. Also, IMO you should always turn off the petcock when you're off the bike. It's such a habit with me...engine off, petcocks off. Not to mention, if gas continues to flow into the downhill cylinder and the intake valve is open, you can get fuel either into the oil and/or fluid will fill the combustion chamber and you'll do engine damage the next time you hit the starter button.

I agree, close the petcock when parked and the problem is gone! I have to get used to that, since riding my fuel injected R didn't require that!
 
Tire recommendation

What tires are y'all using on your bikes? What would be a good combo for the R75/5? Doesn't have to be the best tire out there, would be great if it had that vintage look (whatever this may be). The tires I have on there are "new" in terms of miles however are 15 and 17 years old....

In the last 3 years the only tire I bought was the Pilot Road 4 for my other ride, so I don't really know what to pick for this one.

Thanks, Olaf
 
75/5 tires

If you are really looking for that "vintage look" I do believe Continental is reproducing the classic RB2 and K112 tread patterns in a modern compound. Might not have the handling, grip or longevity of more modern tires, but certainly have that "vintage look" and certainly an adequate tire if not looking for sportbike performance.

Friedle
 
I've got Bridgestone S11 Spitfires on my /5; 110x18 rear, 90x19 front. Love these tires; great in the twisties or out on the slab, and affordably priced.
 
If you like the look of the RB2 or K112, you may want to stay off of any grooved freeways...
 
Couldn't resist and bought the Conti classics for the looks....hope the ride won't be that bad!

Another question, are the front pegs supposed to be offset? I can see why, so the clearance to the cylinders stays the same but feels weird to me.
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Sent from my iPhone using Tapatalk Pro
 
After a bit of time, you won't even notice it. Both of my twin cylinder bikes are exactly the same.
 
Offset pegs

True story. When I worked at the dealership we had a customer come back for a warranty problem. Seems the engine was built with the cylinders offset! He was really upset and wanted a new engine.
 
True story. When I worked at the dealership we had a customer come back for a warranty problem. Seems the engine was built with the cylinders offset! He was really upset and wanted a new engine.

That's a good one! On my R1200R they aren't offset, so that's why I thought there is a mixed set of long/short on my R75 :)
 
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