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Bike Profile - Posted 5th August 2009

1977 BMW R80/7 - Part 7: Rooster Booster
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The Rooster Booster isn't a Bantam turbocharger, but it is the path to BMW joy and happiness, as Martin Gelder explains...

A well set up BMW Boxer is a thing of beauty, a joy to ride, a marvel at covering effortless distance.

A badly set up BMW Boxer is a blummin' nightmare. Coughing, shaking and spluttering; lurching, clunking and wobbling; enough to put you off for life.

The difference between the two can be as little as a fraction of a turn on a throttle cable adjuster, the merest hint of muck in the carbs, or timing that is just slightly too advanced or retarded.

A thing of beauty, a joy to ride, a marvel at covering distance. Sometimes.... Roxanne the 1977 BMW R80/7, a thing of beauty, a joy to ride, a marvel at covering distance. Sometimes.

As my regular reader will know, Roxanne the 1977 BMW R80/7 has a bit of an appetite for contact breaker points. This means that the distance between freshly serviced perfection and juddering hell can be as little as 500 miles. If I didn't know how sweet the ride could be, I probably wouldn't notice the difference, but I know the old girl can do better .

Replacing the points and condenser together gives me perfect timing for a few hundred miles, but all too soon the points are pitted and the sparks are either arriving too soon or too late. I'd given up trying to find out if it was the pattern condensers, OE points, original coils or HT leads and plug caps that were the problem, but then RealClassic message board regular Chris from suggested I try a Rooster Booster points assisted electronic ignition system, from

The Rooster Booster system is a box of electronics that uses the bike's standard contact breaker as a low voltage, low current switch to trigger a spark at the coils. Because the voltage and current are lower, erosion and burning or pitting of the points is greatly reduced; in my BMW's case, this should mean that the ignition timing stays accurate for much longer, improving starting, throttle response, tickover, general running and so on. See "beauty" and "joy", above.

The system bypasses the condenser but retains the standard points and automatic advance mechanism, and it uses the standard coils and HT leads. This means that it's easy to put the bike back to standard if necessary; good for peace of mind if nothing else.

Before fitting the Rooster Booster I changed the points for a new set and spent some time carefully getting the ignition timing spot-on before checking that it started and ran; I wanted to be able to compare the timing later to see if it had drifted away from the optimum.

Instructions supplied. Mighty Thor not required.

The kit is supplied with fitting instructions, but these are fairly generic rather than written for a particular model of bike. Despite there being only six steps, and four wires to connect, I took the precaution of printing out a wiring diagram for the bike before starting. The BMW uses an unusual system of two 6 volt coils connected in series, and I wanted to be sure I was pulling apart the right connectors.

System loosely connected to see if it's going to work

Installation itself was simple; much more straightforward than I expected. The various connectors for the coil and battery simply needed connecting to the right places on the coils and battery, and came with insulated sleeves where necessary. Because the BMW's points are a long way from the coils and battery (they're at the front and bottom of the engine, below the crankshaft) I used the existing wiring, making up a double-ended male spade connector-thing to allow the condenser to be bypassed. This one, self imposed, step took longer than the rest of the installation put together.

Rooster Booster box fits behind coils and above air filter. LED shows points are open. Rooster Booster fitted to BMW R80/7

The ignition box itself is a little bigger than a box of 20 cigarettes, and fitted snugly - with the aid of a couple of cable ties and some closed cell rubber cushioning - behind the coils. Slightly longer wires would have made finding a home for the box easier, but the end result is neat and tidy.

And - to my slight surprise, because I have little faith in my ability to tinker with electrics - the bike fired up on the first touch of the starter button and eased into a very even tickover that was possibly better than with the standard points and condenser set up.

Since then the timing has stayed spot on; the bike starts readily, responds to the throttle crisply and thrums along smoothly as a good BMW should. The bike has been much more consistent in its behaviour, staying exactly in tune for longer than it has managed in the past, and this can only be down to the Rooster Booster.

With the engine more predictable, I'm now noticing the vagaries of the handling, so I think the next episode is going to involve two new tyres and possibly a handful of bearings....


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