Belt drive/alternator install

OK guys, I've decided to turn my race bike into my road bike so I have a load of work to do, fitting lights etc, but the first thing I need to sort out is an alternator and belt drive.

The bike is an Atlas engine ( inclined forward like a Commando) in a slimline frame with a single row primary chain and AMC clutch/gearbox.
See photo:



The reason I want a belt drive is because although a single row primary chain is OK if you do short races and lube it every race, longer rides on the road would probably wear the chain out pretty quick.

I'll fit an alternator probably a Sparx unless anyone has any better suggestions.

My question is about the width of all these components. It seems that the width of my engine sprocket+spacer where the rotor used to be is about 65mm, but internet research indicates that a belt drive pulley is 37mm, the spacer 5mm and the rotor 35mm. That makes 77mm so I can't see how it will fit on the crank.

Is an Atlas crank shorter at that end than a Commando? The Commando had a triplex chain, so maybe that's the case.

pommie john said:

OK guys, I've decided to turn my race bike into my road bike so I have a load of work to do, fitting lights etc, but the first thing I need to sort out is an alternator and belt drive.

The bike is an Atlas engine ( inclined forward like a Commando) in a slimline frame with a single row primary chain and AMC clutch/gearbox.
See photo:

The reason I want a belt drive is because although a single row primary chain is OK if you do short races and lube it every race, longer rides on the road would probably wear the chain out pretty quick.

I'll fit an alternator probably a Sparx unless anyone has any better suggestions.

My question is about the width of all these components. It seems that the width of my engine sprocket+spacer where the rotor used to be is about 65mm, but internet research indicates that a belt drive pulley is 37mm, the spacer 5mm and the rotor 35mm. That makes 77mm so I can't see how it will fit on the crank.

Is an Atlas crank shorter at that end than a Commando? The Commando had a triplex chain, so maybe that's the case.

Click to expand...

John,

I have run standard sized (Lucas) rotor and stator while using 30mm belt drives, but not 40mm. I am not sure about this setup on an Atlas, but can check for you today as I have one in the shop now and can do a trial fit of a 30mm pulley and alternator rotor to check.

I have fitted a lucas rotor/stator to my 40mm belt drive. Both with a primary case and without. .
With a primary if you use the early pointy primary cover and remove the timing indicator, everything fits.
With out I made an alternator mount.

Either way required I make a longer alternator nut and spacers.

Holmeslice said:

pommie john said:

OK guys, I've decided to turn my race bike into my road bike so I have a load of work to do, fitting lights etc, but the first thing I need to sort out is an alternator and belt drive.

The bike is an Atlas engine ( inclined forward like a Commando) in a slimline frame with a single row primary chain and AMC clutch/gearbox.

The reason I want a belt drive is because although a single row primary chain is OK if you do short races and lube it every race, longer rides on the road would probably wear the chain out pretty quick.

I'll fit an alternator probably a Sparx unless anyone has any better suggestions.

My question is about the width of all these components. It seems that the width of my engine sprocket+spacer where the rotor used to be is about 65mm, but internet research indicates that a belt drive pulley is 37mm, the spacer 5mm and the rotor 35mm. That makes 77mm so I can't see how it will fit on the crank.

Is an Atlas crank shorter at that end than a Commando? The Commando had a triplex chain, so maybe that's the case.

Click to expand...

John,

I have run standard sized (Lucas) rotor and stator while using 30mm belt drives, but not 40mm. I am not sure about this setup on an Atlas, but can check for you today as I have one in the shop now and can do a trial fit of a 30mm pulley and alternator rotor to check.

Click to expand...

John,

I have measured a '67 Atlas crank and it's the same as a Commando, so if you're running a 30mm belt you'll have no problem with alternator spacing. If you're running a 40mm, then you'll have to do some mods as Bwolfie states.

Maney offers an adaptor for his race cases to mount inner primary case that allows Lucas alternator to fit under factory primary cover with his 40 mm belt drive, ie: there is about 10mm/.5" room to spare for alternator to case cover with a 30 mm wide pulley. Ping Maney directly as he may already have figured out your solution. Rather rare for any one to use Maney engine on road legal lighted bikes so rare to see charger systems mounted with belt drives fully sealed up.

Hi Hobot

I think the Atlas inclined will put the alternator studs in the wrong place for the chaincase.

Chris

Thanks for the replies everyone. This is such a great forum. So I'll go for the 30mm belt and I'll probably make my own primary cover a bit like the one in the photo but wider.

Why not try something different? http://www.pbase.com/jeandr/image/108250539 (tooting my own horn)

Jean

bwolfie said:

Click to expand...

Hi bwolfie

In this photo, where did you get the alloy plate that bolts to the crankcase and supports the stator? Did you make it yourself? If so do you have a drawing that I could give to a local engineer to get it copied, or could you make one for me?

Regards
John

I made it. No drawings, all stored in the grey matter. pretty simple to do. center hole fits over case spigot.
it's just wide enough to pick up all 6 fasteners. countersunk fasteners holding the 3 standoffs to the ring.

Brent does yours do road life w/o side plates on front pulley?

both side plates are there