Belt driven alternator set up? Pics included

[peanut]

has anyone got any further with experimenting with this ?

Seems a shame that some clever chap can't design something to use with a miniature alternator. It sure would be better than the stock alternator and a whole lot cheaper than the PMA mods seem to sell at at the moment .

I was thinking it should be possible to fit a friction wheel directly onto the drive chain in the same manner as the chain tensioner arrangement for stretched wheelbase hardtails.

The drive shaft could presumably be extended in order to fit the alternator away from the chain

 

[weaselbeak]

You can't do it this way on an XS650, but it is made to order for a Moto Guzzi. I don't have a better picture, but it just got back from a 2000 mile trip to Canada.

 

[peanut]

wow that looks the business
Driven off the crank. is the crank slung front to back on the guzzi ?

 

[weaselbeak]

Yes it is. The alternator is 35 amps, stock was 20 being optimistic. 2 wires, no R/R needed.

 

[TLCbobber]

a whole lot cheaper than the PMA mods seem to sell at at the moment .

pma doesn't have to cost a lot. I sourced used rd350 ypvs stator/rotor and Y plate on ebay and made my adapter plate using nothing more than a set of dividers to mark it out on 5mm Al plate, Irwin clamp to fix it to the table, hand cranked drill and swiss army knife to cut it out, then dressed it nice and round with a file. Plate design I found here https://thexscafedotcom.wordpress.com/2011/01/12/xs650-permanent-magnet-alternator/

A new regulator/rectifier alone will probably cost more than what I've spent so far.

 

[peanut]

pma doesn't have to cost a lot. I sourced used rd350 ypvs stator/rotor and Y plate on ebay and made my adapter plate using nothing more than a set of dividers to mark it out on 5mm Al plate, Irwin clamp to fix it to the table, hand cranked drill and swiss army knife to cut it out, then dressed it nice and round with a file. Plate design I found here https://thexscafedotcom.wordpress.com/2011/01/12/xs650-permanent-magnet-alternator/

A new regulator/rectifier alone will probably cost more than what I've spent so far.

thats what I like to see ...ingenuity I might try this myself.
It would give me much more pleasure than just buying one and also give me something to do this winter

Thanks for the linky I'll have a looksee.

trouble is I wouldn't know which bike models have PMA's that could be adapted to fit a XS650 . There are stacks for sale cheap on ebay but you could end up with a dozen before you found a suitable match

 

[retiredgentleman]

has anyone got any further with experimenting with this ?

Seems a shame that some clever chap can't design something to use with a miniature alternator. It sure would be better than the stock alternator and a whole lot cheaper than the PMA mods seem to sell at at the moment .

I was thinking it should be possible to fit a friction wheel directly onto the drive chain in the same manner as the chain tensioner arrangement for stretched wheelbase hardtails.

The drive shaft could presumably be extended in order to fit the alternator away from the chain

The stock alternator is a high quality unit, and works very well in my opinion. The weak area was the original stock rectifier and mechanical regulator. Replace those 2 items with modern equivalents, use a 40 watt halogen headlight, LED tail/brake lights, and the alternator is very reliable.

Also, use some spacers on the small alternator cover, to allow for cooling air.

This is my ninth season with the stock alternator, and it still just purrs along at 14.2 volts as I drive down the highway.

Everyone likes to talk badly about the stock alternator. Please inform me as to why its a bad alternator??

 

[peanut]

lets go back to using candles for light shall we . Candles worked well enough for Isambard Kingdom Brunel to design his railways ships and bridges by

 

[peanut]

split post ?

 

[barncat]

in terms of the bike at top of thread: nice looking ride other than the alternator... i understand the novelty/industrial look, and it would simplify the wiring, but the open belt danger of a grabbed hand, clothing or or shoelace etc... not for me. kind of like riding without a front brake... as others noted, a safer orientation low and forward of crank makes sense for an optional total loss street/race bike with belt on or off.

as TLCbobber points out, a PMA setup doesn't have to cost much. mine was about 45 bucks each for new VN800 stator and aftermarket banshee style rotor plus 15 for a new 5-wire reg/reg, plus 5 bucks for a 10,000uF capacitor out of a Peavey power amp. all ebay. made my own stator bracket as per the "DIY PMA bracket" thread i posted weeks ago. it's great to get rid of that battery, crappy old wiring harness and vintage electronics- and rewire from scratch couldn't be much easier. it's also very handy that the early left hand handlebar switch has on/off to kill all power to lights for kickstart.

 

[retiredgentleman]

I doubt anyone could 'inform 'you RG

Thank you for your witty reply, but I'm still waiting for answers as to why their stock alternator does not work on their bike.

 

[tonyc]

I agree with R.G. there is nothing wrong with the old alternator as long as you do proper maintenance. After saying that I have been using a Sparx set up from M.M.M. for about six years and I am totally happy. The only error was mine by not lock-titing the mounting bolts.
It is now maintenance-free. Very expensive. When building my bike the alternator was toast, and this helped me make my decision.

 

[retiredgentleman]

I agree with R.G. there is nothing wrong with the old alternator as long as you do proper maintenance. After saying that I have been using a Sparx set up from M.M.M. for about six years and I am totally happy. The only error was mine by not lock-titing the mounting bolts.
It is now maintenance-free. Very expensive. When building my bike the alternator was toast, and this helped me make my decision.

Yes, Tony that pretty well sums it up. Many of these bikes went through 3 or 4 or more PO's, and most had no clue as to alternator maintenance. They let brushes wear down to nothing, never cleaned the slip rings, tried to charge dead batteries, constantly drive with the head light on high beam to overload the alternator etc, etc.

Tony if your bike had those same "no maintenance" owners, its not surprising the poor tortured alternator died on you.

When I bought my XS650 back in 2007, the XS650 websites all said the stock alternator was crap and fails often. It was repeated over and over, so it just had to be true! Everyone said you better buy a PMA, or you'll be left dead on the side of the road. Well I just do a little maintenance and guess what...................the stock alternator works amazingly well.

 

[weekendrider]

Now RG aren't you getting alittle carried away?
The 'old boy you got the tip of standing the cover off from never said the OEM equipment was shoddy. Don't think grizld1, 5twins, jayel, or curly ever said you had to convert. Or more recently gggGary, xsleo, 650skull, or TwoMany.

I can understand someone wanting to use an alternate if it achieves the look they are wanting. A big ole battery box just doesn't cut it in some cases.

 

[retiredgentleman]

Now RG aren't you getting alittle carried away?
The 'old boy you got the tip of standing the cover off from never said the OEM equipment was shoddy. Don't think grizld1, 5twins, jayel, or curly ever said you had to convert. Or more recently gggGary, xsleo, 650skull, or TwoMany.

I can understand someone wanting to use an alternate if it achieves the look they are wanting. A big ole battery box just doesn't cut it in some cases.

No WER, I don't think I'm over the top on this. If I had a dollar for every time I saw a post about how bad the stock alternator is, I'd be a rich man by now.

Yes, I agree, the names you mentioned don't badmouth the stock alternator. Its the uninformed biker novices with no electrical knowledge, that never do any electrical maintenance, that cry out how Yamaha sells crap electrical parts.

 

[TLCbobber]

I think the whole pma thing started with people whom raced were looking for ways to fit modern parts and ideas to an aging bike they were pushing harder than most people. Lets face it, the manufacturers moved away from brushed assemblies to PMA because it is a step in a better direction however small the step. Just because you modernise something it doesn't mean it was bad to begin with.

Then you get a resurgence in popularity for these bikes for modding, bobbing and chopping, somebody does a bit of digging on the net and finds these upgrades you can do, tells the world about it, sees all the interest and potential for making some money. Enter the marketeer who says the original set up was bad in the name of sales.

Sure I went PMA, but when I got my xs the whole bike was bad, standing 25 years in a garden exposed to every type of weather will crap everything out. I could have probably saved the charging unit but since everything else electrical was trashed it could only be easier to rebuild fresh and simple. Don't think anybody would want to build a concourse bike out of what I started with. Usable/repairable parts essentially amounted to frame, trees and fork lowers, rims/hubs/axles, siezed engine and light lenses.

If I had an xs in fairly stock form which was as nice as what some guys have on here, would I go pma? probably not... not if what I had was doing it's job even if it took daily checks. But this is a hardtailed bob... and part of me wishes I hadn't cut the frame. Maybe I'll keep stock frame on the next project.

 

[RedEyeWhiskey]

I use a Delco 10si Chevy alternator driven by the chain. I need to go down a couple teeth so it spins faster and charges at lower speeds, but it works.

 

[XSLeo]

If a PMA is better than a field excited alternator how come cars, pickups, trucks, buses and such don't use them.
Leo

 

[tonyc]

They are not better, but they are different and require maintenance. Cars, trucks, and buses
use alternators that are almost maintenance free for hundreds of thousands of miles. These do not spin as fast as ours on the XS650's.

 

[XSLeo]

On most cars I've had the alternator spins faster than the XS650 does. Most have a large pulley on the engine, small pulley on the alternator. This runs the alternator faster. This is done so it can charge at idle speeds.
On our XS650 or most bikes the alternator spins at engine speed. This lack of speed at idle is why they don't charge at idle. Most won't show a charge till about 2000 rpms.
A car idles around 800-900, if the alternator spun at that rpms it wouldn't charge at all. So they spin it faster by using a big pulley and a small pulley. This keeps the alternator spinning well above the 2000 rpms to insure a good charge at idle.
On bikes that can be set up to use a belt driven alternator could have better charging at lower rpms. On bigger bikes with plenty of power it would work but on smaller bikes with less power the extra draw of a good charging system would take too much HP.
Leo