Alternators

Post by **Crazymanneil** » Mon Nov 03, 2008 9:55 am

Anyone any suggestions for alternators? I'm considering something for my bike as the build progresses. I'm thinking something direct drive off the crankshaft where the pulley used to go. Perhaps a permenant magnet job off another bike with some mounting hardware. I see there are charging kits for harleys - do these go inside the primary chaincase?

Need enough amps for charging and maybe running heated grips or jacket so like 20A? I think the original car one would be too much and bulky/suseptible to dirt ingress. Any bikes I should be looking at?

(this is all assuming I get the engine to run!)

Neil

Post by **Stuart** » Mon Nov 03, 2008 10:15 am

I know guys in Germany favour using the 2CV alternator because of its small size. Belt drive job.

Post by **Diesel Dave** » Mon Nov 03, 2008 12:40 pm

There are a fair few alternators to choose from - Goffy sells a 120watt jobbie fairly cheaply:

http://www.norbsa02.freeuk.com/goffyelectrex.htm

The issue would be boring through the rotor to fit the crank end - it might fall apart, especially at 3600 rpm.

Any bike alternator from a breakers could be made to fit but choose the regulator that matches as some are 3 phase.

Dave

oilburner · Post by **oilburner** » Mon Nov 03, 2008 2:14 pm

It's a long shot, but maybe Alan Forbes will sell you a 384 watt alternator that was fitted to his modern Indian Four motorcycles. Alan runs Motolux Indian in Edinburgh, Scotland. The pictures are of the Swedish Wiking on which Alan's Indian is (was?) based.

FYI

Post by **Crazymanneil** » Mon Nov 03, 2008 4:08 pm

hmm thanks for those ideas. The Wiking alternator looks like a compufire for harley -

http://www.compufire.com/harley-main.html

32 amps too.

I like the idea of an alternator from a breakers too. You make a good point about it possibly coming apart at 3600rpm, but its worse in my case as the engine I have can rev to 4500 rpm.

I'm wondering now if the entire alternator off another bike might work. Take the stator in the engine case off and make a nice wee alloy plate with a bearing carrier to go on the back. Then make up a shaft to go from the engine to the original rotor. It would be all down to balancing I guess.

Neil

oilburner · Post by **oilburner** » Mon Nov 03, 2008 10:58 pm

Another thought. The 280 watt Bosch alternator from a Moto Guzzi or aircooled BMW mounts on the end of the crankshaft and is good for over 7000 rpm. You would have to make a mount for the stator. The BMW rotor mounts onto a taper on the end of the crankshaft, I don't know about Moto Guzzi. BMW setup below:

oldbmw · Post by **oldbmw** » Mon Nov 03, 2008 11:20 pm

The later BMW's use a small car alternator, I suspect they will be much cheaper than a bike specific one and can be driven by a simple pulley.

taildraggin · Post by **taildraggin** » Tue Nov 04, 2008 2:18 am

There is a nifty gen-to-alt conversion unit that's pretty compact. Gear driven, though:

http://www.jpcycles.com/productgroup.as ... BCC4241A08

arnaud · Post by **arnaud** » Tue Nov 04, 2008 9:24 am

a puley and genny outside makes inspection easier, but in case of an enfield, the puley would get trough a hole in the primary case, where the oil is..
what about a puley on a wheel hub? the generator would be mounted on the frame where it is also shaking up and down with the wheel. i don't know if that would hold long. The same for fitting a stator on the wheel axle and rotor on the hub.. maybe an idea??

As for a china diesel and maybe more simple diesel engines, the have the electric starter at the front of the engine which is driven bij the big flywheel. I dismounted it to fit the engine and subframe in the enfield frame. But when you make bigger adaptions maybe an alternator could replace the starter?? or would the RPM's get too high because of the big flywheel and the small sprocket on top..
Just brainstorming over here..

pietenpol2002 · Post by **pietenpol2002** » Tue Nov 04, 2008 3:26 pm

Below is another consideration. Note that the chaps flying the Corvair engines in their aircraft routinely use this application and advise that to turn this dynamo beyond 4250 RPM's is "pointless", thus our 3600 RPM is of little concern. Bear in mind that output is directly proportionate to RPM's. The beauty is that they are readily available anywhere in the world that Kubota's, John Deere's or Yanmar's are sold or salvaged.

http://www.thevincent.com/McDouglator.html

http://tinyurl.com/6kdkkk

Ron

Post by **Crazymanneil** » Tue Nov 04, 2008 8:37 pm

Great ideas guys, I'm reading away about them all. Original smart engine alternator (which I don't have anyway) would perhaps be simplest and lots of power, but is in an awkward place at the bottom of the engine so its an opportunity to consider things like the bike driven ones adapted to the crankshaft.

Anyone any idea where the compufire alternator goes on a Harley? I read that its somewhere in the primary case, but is it front sprocket or clutch basket?

I noticed a Kawasaki GT550 alternator on ebay which looks chunky but can't find any specs on it. Ideally would like one off a bike that the rotor sits inside the alternator cover completely - that way I could make up a rear cover plate to enclose the whole thing.

Either that or an off the shelf one like the ones suggested here - I'll look through them.

Will keep reading

Neil

sbrumby · Post by **sbrumby** » Tue Nov 04, 2008 9:03 pm

Check out Denso alternators , very small and very powerfull, I got mine for the first bike I think off a nissan starlight, £10 from a scrap yard. There is a even smaller one fitted to the small van bedford or suzuki.