Alternative Electric Start

[Mosin]

This is an entirely hypothetical thought. There must be something wrong with it, or else someone far more intelligent than me would have thought of it already. But here we go anyway...

Steve McFarlane (and others) have successfully adapted A7 and A10 bikes with an electric start which, as far as I can tell, incorporates a starter motor somewhere under the bike which somehow rotates the engine using some sort of additional drive on the primary drive chain. A significant part of the problem here is locating and housing the new starter motor.

However, all our bikes already have a nice big electric motor fitted on them. We don't use it as a motor though. We use it as a dynamo. My understanding is that a dynamo and a motor are more or less the same thing, just doing different jobs. So would it be theoretically possible to start the bike by firing a hefty current fired through either the existing dynamo, or a starter motor housed infront of the engine in its place and rotating the engine via the dynamo drive chain?

Then once the bike is running, simply switch the motor back to being a dynamo again in order to keep the battery charged.

If this were possible, it might be possible to provide the convenience of an electric start for far less cost, and without having to alter the aesthetic appearance of the bike at all.

Like I say, I am sure there must be some reason why it wouldn't work. But it's certainly a thought worthy of pondering and speculation...

[CheeserBeezer]

Unfortunately, at least two issues here. For the dynamo to spin the engine fast enough it would have to be much beefier than it is. Even with low-draw accessories the dynamo is prone to overheat and throw the wires off the commutator. Secondly, you'd still have to design a drive mechanism which improves on the tiny chain between the idle gear and the dynamo sprocket. sorry to rain on your parade. The theory certainly has some merits in principle but, in practice, it cannot work with existing components.

[Mosin]

I had guessed that a far more powerful motor/dynamo would be required. But it's nice to know that the idea isn't total insanity!

[Angus]

I think that is what has been done for fitting Velocettes with a electric start, although I assume the dynamo/starter motor is an uprated unit.

[Rex]

Given the general weediness of Miller dynamos on Velo's, I would say that's a definite.

[Bsareg]

I've fitted the  Pearson electric start to my goldie, and , unless you're almost on you're hands and knees it's practically invisible. I don't know why it can't be fitted to an A series as the primary is similar except for the inner case but there may be a reason I haven't thought of......
 I've  just thought of one, no exhaust lifter.

[a101960]

" I've  just thought of one, no exhaust lifter." I have the Steve McFarlane starter fitted to my A10 it utilises a reduction gear.

[chaterlea25]

Hi All,
Back in the day several cars and bikes were equipped with "Dynastarts"
Some were built onto the end of the crankshaft and some were the same size as Lucas car dynamos of the 50s and 60s
The newest bike so equipped that I can think of  are Guzzi Neuvo Falcone's, that are v belt driven. One issue is weight, memory says they weigh about 9kg ? And you also need a substantial battery.
They were popular with inboard marine engines, also used to convert early Morgan 3 wheelers to electric starter
They can still be bought but be careful as some on offer are starters only not having the dynamo function.!!

The Steve McFarlane A10 starter has a gear added to the engine sprocket this engages with a sprag clutch gear and reduction gearing then a chain drive to the motor.
The Pearson GS starter has a chain sprocket on the crank  driven by a smaller sprocket i guess the reduction is about 3 to 1?
That means the small sprocket / chain is rotating 3 x times the engine speed

I would think that the drive gears on the A10 camshaft and crank  would struggle badly if enough torque  was applied to turn the engine over?

John

[Triton Thrasher]

A drive train engineered to drive a camshaft and magneto is not strong enough for a starter.

The other half of BSA/Triumph did a good job of demonstrating that with their Bonneville Electro.

So did Norton, but they only demonstrated it to themselves and never brought it to market.

[Joolstacho]

In these days of 'everlasting' LiPo batteries and super-efficient LED lights, unless you do a lot of night riding perhaps you could just replace the dynamo with a starter motor. Obviously needs a beefed up drive. Is this a silly idea? (Probably!)

[chaterlea25]

Hi Jools and All,
A friend who is now in his late 80s has fitted a gear reduction starter in place of the dynamo on a 1927 New Hudson driving the primary side of the crank, all bolted on so easily reversed if desired.. previously he fitted electric starters to his black Ariel and BSA V twin

John