Buying advice for guy returning to BMWs - R75/6

[Porge]

Rob,
Cheers for the pic. I'll start trawling the site for other assembly questions.

Have removed the wiring for the horn as the switch is clean. Will troubleshoot that later. With my jump start device, I've had the bike cranking over nicely, showing a fat spark on both jugs. Won't fire, and the plugs are dry, so I'll start tracing fuelling issues. Guessing the twin sets of diagrams is a bit of a giveaway.

[Rob]

Regarding horns, I would start over from new and give yourself a BIG advantage out on the road.

Made by Fiamm, OE on the better airheads at the time. No rider should be on the road without them, IMO. (and they are cheap, and available in nearly any car parts store, worldwide)
Don't forget to wire them through a 30 amp relay.
There is a high tone, and a low tone, and the combination of the two makes you sound like a large truck. I keep my finger poised over the horn button in city traffic. More than once I have had someone start to move into my lane, only to jump right back when they hear those blasters!
Always a thrill.

[Ken in Oklahoma]

Have removed the wiring for the horn as the switch is clean. Will troubleshoot that later. With my jump start device, I've had the bike cranking over nicely, showing a fat spark on both jugs. Won't fire, and the plugs are dry, so I'll start tracing fuelling issues. Guessing the twin sets of diagrams is a bit of a giveaway.

Your existing diaphragms are probably just fine. Diaphragms with holes in them will screw up the response of one or both carbs. Your carbs will probably be just fine when you clean them thoroughly.

Having said that you will probably want to have a couple spare diaphragms in your spares stock. Those diaphragms fit certain Stromberg carbs on certain British sports cars, so they are not horribly expensive. Somebody here will probably remember just which ones you need.

Cleaning thoroughly to me includes carefully looking at all the drillings and orifices on the carb body. Bing used to have a diagram on their site which was very useful. What you want to know is where every minute orifice is, the drillings that make the passageways, and where the gas or air go accordingly. (Don't forget the little round well in the float bowl.) Disassembly of the carb replacing bad looking components, coupled with a good initial setup (slide needle in the right notch etc.) setting the float height correctly, will go a long way toward the bike starting right up and being relatively painless to adjust properly, idle speed, sync, etc. (P.S. I'm opposed to dunking carbs in some vat of noxious stuff and somehow hoping that the noxious stuff will find it's way to the plugged area and dissolve the hardened gunk there. Your, I mean my, cleaner of choice is spray carb cleaner found at parts houses and Wal Marts everywhere.

Ken

[Porge]

In the quiet of the shed, the oem horn sounds plenty loud!

Cheers for the advice on carbs. I was going to do the spray cleaning. Have toyed with the idea of a small ultrasonic cleaner for home use.

[Porge]

In the quiet of the shed, the oem horn sounds plenty loud!

Cheers for the advice on carbs. I was going to do the spray cleaning. Have toyed with the idea of a small ultrasonic cleaner for home use.

[barryh]

Those diaphragms fit certain Stromberg carbs on certain British sports cars, so they are not horribly expensive. Somebody here will probably remember just which ones you need.

Stromberg CD150 diaphragms available from several sources as the carbs were commonly used on 70's British cars. I had a 72 Humber Sceptre with twin Strombergs. Most common source would be any spares outlet that caters for classic Triumph sports cars. Cost in the UK approx. £4.00 vs £21.00 for the genuine item.