Topic: 550 alternator on a 650

[JSGAuto]

Here is the info about Tim (the rotor guy) I found on another message board. 

"From what Tim tells me they had a severe electrical storm there a couple of weeks ago which wiped out his PC and some other equipment. It has pretty much shut him down and he is not taking any more orders at this time until he can get things straightened out. "

[Ibsen]

I don't know if this guy can help you with questions about your rotor, but he does know a thing or two about charging systems. And he can supply reg/recs for all the classic Hondas.

http://www.oregonmotorcycleparts.com/index.html

http://www.oregonmotorcycleparts.com/FAQ.html

[Pinhead]

Getting back to the original subject... I just received my alternator casing from a CB550K and the bolts line up. It is, however, not as "deep" as the 650's casing is. I hope it's just because the 650's electromagnet rotor is longer as well. Now I need to find a rotor, stator, and field coil off a 550 to see if it'll all fit.

Has anyone taken measurements to compare the crank ends from the 550 vs 650? How about 650 vs 750?

[bill440cars]

Getting back to the original subject... I just received my alternator casing from a CB550K and the bolts line up. It is, however, not as "deep" as the 650's casing is. I hope it's just because the 650's electromagnet rotor is longer as well. Now I need to find a rotor, stator, and field coil off a 550 to see if it'll all fit.

Has anyone taken measurements to compare the crank ends from the 550 vs 650? How about 650 vs 750?

        Pinhead, I was going to measure a 550 crank that I have out and I got sidetracked and didn't get it done. I'll try to get that taken care of. Now, if we can get a 650 measured.  Later on, Bill

[scunny]

just had a look at my crank(650), it is a long taper with a shoulder, I haven't got a vernier at home at the moment, but can do it tomorrow, what measurements do you need ?

[bill440cars]

just had a look at my crank(650), it is a long taper with a shoulder, I haven't got a vernier at home at the moment, but can do it tomorrow, what measurements do you need ?

  scunny, I believe the measurements needed are: diameter at the end of the crankshaft, length of the taper and the diameter at the beginning of the taper. Does that pretty much cover it guys, or did I miss something? I'll really try to do the 500 shaft that I have, tonight or tomorrow. Later on, Bill



   UPDATE:  I'm going to have to apologize. I was thinking (my 1st mistake) that I already had the rotor off of the crankshaft and I don't! So,  I'm going to have to remove it before I can do anything.  Sorry bout that.    Later on, Bill

[Pinhead]

just had a look at my crank(650), it is a long taper with a shoulder, I haven't got a vernier at home at the moment, but can do it tomorrow, what measurements do you need ?

  scunny, I believe the measurements needed are: diameter at the end of the crankshaft, length of the taper and the diameter at the beginning of the taper. Does that pretty much cover it guys, or did I miss something? I'll really try to do the 500 shaft that I have, tonight or tomorrow. Later on, Bill



   UPDATE:  I'm going to have to apologize. I was thinking (my 1st mistake) that I already had the rotor off of the crankshaft and I don't! So,  I'm going to have to remove it before I can do anything.  Sorry bout that.    Later on, Bill

I think that should do it. Maybe the diameter of the bolt and the thread pitch, etc. would also be handy, though you can always find another bolt to use.

[scunny]

ok, sorry I can't send a drawing but after scewing around wit the putor trying to make it go better, some things no longer work

 650 crank is 30 mm at the shoulder, is then cut to 25mm in diameter and tapers down to 19mm over a distance of 40mm. cant find the bolt at the moment, but it is 10mm. hope this helps.

[Pinhead]

Great! Now we just need someone to measure a 550.

On the other hand, someone could simply buy a 550 rotor and try to fit it on their 650 (or vice versa). I'm considering doing it, since I've already got the 550 cover that fits. It was from a '74 550K.

One last question about the crank measurement... What is the total length from the engine block to the end of the crankshaft?

[scunny]

from the bottom casing surrounding the oil seal to the end of the crankshaft is 38mm. I'd love to help with the 550 rotor, but I've got enough work in front of me at the moment, do you Know how many individual parts make up these bikes, 100 million zillion give or take a couple. they sure are pretty tho

[Demon67]

Pinhead I to have same problem and am interested in permament mag rotor seems to me it should work.
Bill

[Pinhead]

Pinhead I to have same problem and am interested in permament mag rotor seems to me it should work.
Bill

Technically the 550's charging system isn't "permanent magnet" (not a dynamo system). There is a field coil in the center of the system, with a soft iron rotor spinning around it. Surrounding the rotor is the stator. The DC flowing through the field coil creates a constant magnetic field. Since the stator can only generate while in the presence of an oscillating field, the soft iron rotor is spinning between the field coil and the stator to block the field at intervals to transform the field strength into a sine wave. That's why the stator outputs AC that needs to be rectified (converted to DC) to be usefull.

The 650 uses an electromagnet rotor instead of a soft iron rotor. This makes the field spin instead of being blocked. I don't really know the advantages of this sytem, but the disadvantages are obvious. Reliablity has been compromised. That is why I'm trying to convert to the 550's system.

Even if the field coil from the 550 won't fit onto the 650, I believe a simple coil could be made to work. A lot of copper wire and some patience may prove to be even stronger and more efficient than the OEM coil. Hopefully, though, the 550 coil will work to save a lot of time and effort.

[Pinhead]

Well, it looks like this project is a no-go. I got an alternator cover from a '77 550K.The cover could be made to work, but it won't look good. the 550's case is actually bigger than the 650s. Also, the 550 rotor has a larger outisde diameter while going on a smaller crank end. The 650's stator ID isn't as big, either. All of the parts I've tried were from a '77 550K. Are there different casings on different year 550s?? I've heard of people using the 650 crank in a 550... What did they do to make the alternator system work?? I'm really at a loss now...

Edit: Now that I've bought all of these parts that won't work on my bike, I'll put them all up for sale or trade. I've got a '77 550K alternator cover, rotor, and field coil. I'll make a new post in the for sale section.

[Pinhead]

Now that I think of it, if there were different rotors for different year 550s (some of which would fit on the 650 crank end) than this project could work. However, I'll have to replace my rotor, stator, field coil, and cover... All of which I already have and need to sell.

Are there different-sized rotors for the 550s?

[Pinhead]

Anybody?

[Demon67]

Pinhead I don't know where your at with alternator problems but I've heard of a fix using a yamaha alternator rotor from a 81 xj 650, seems to work just slight difference in depth.
Bill.

[bryanj]

All the 500/550 rotors and coils are the same part except for vERY early 500 coils and they have a different block connector, round pin instead of spade, The main person doing the 650 crank job is Ted Hayes, and his is for racing so he probably dont use a generator

[crazypj]

The 650 IS just a bored and stroked 500. (the 550 is basically just a bored 500)
There are only detail mods between all the engines.
You should be able to either bolt straight on the 550 (or 500) generator (with cover, etc) or have minimal mods (possibly a spacer?)
They are both electromagnetic alternators, one uses brushes, one doesn't, there should be minimal messing about with wiring (if any, maybe change a male to female or similar?)
If you can get hold of the parts easily just do it. If you have to buy everything you may as well get 650 stuff.
The main reason I've seen the generators fail is bad battery. The generator cant put out enough amps to charge and overheats. Its not designed for max out put for extended periods.
The 'normal cycle of events to failure goes something like this.
Battery low.
 Jump start from auto, or bump start
 rectifier/regulator overheats, putting out max amps trying to charge almost dead battery
 Batter doesn't charge or boils over and distorts plates
New battery fitted.
 Faulty rectifier allows battery voltage to backfeed through stator windings which cooks it
Buy a battery tender or similar and keep batter voltage up (or ride everyday for at least 20miles without stopping)
PJ