Rectifier ?

[Anonymous]

My bike is a 78 GS1000 having some charging issues. I have gone through the bike once with the stator papers but pland to do it again as a precaution but it appears the R/R is bad. Does anyone know if a 79 GS1000s R/R will work on my bike? I know the Suzuki part number is different but I am wondering what the difference is. I believe the 78 used a seperate rectifer and regulator while the 79 (part number 32800-49140 if this helps at all) used a combined unit. I am just wondering as I can get a 79 one locally brand new for about 25 bucks! Way cheaper than an Electrix model.
It is my understanding that these go bad in phase 3 (lights on). If I CAN use the 79, is there also a way I can splice the phase 3 out of the system so the rectifier wont go bad (like the gentlemen did when he used the Honda rectifier in the posting on this site)?
Again, you people are awesome and all this help goes to show the love that we have for these machines! I will have piled WAY more money into this machine than it is certainly worth, but to me its STILL money well spent (but if I can save some thats great too!)

[IanFrancisco]

The same $25 can probably get you a Honda CX500 RR. I wouldn't go with Suzuki OE, I don't think there's a way to circumvent the "3rd phase not being regulated" design flaw of the Suzuki part.

[earlfor]

The 3rd phase is regulated, its simply that with the headlight off, there is no continuity on the charging loop and the battery is being charged only by the two remaining phases.

Bypassing the headlight loop on the charging circuit is easily done. It is not a good idea to do this if you intend to run the bike with the headlight off as the extra charging capacity will cause too much current to be shunted to ground and that will overheat and toast your R/R.

Earl

The same $25 can probably get you a Honda CX500 RR. I wouldn't go with Suzuki OE, I don't think there's a way to circumvent the "3rd phase not being regulated" design flaw of the Suzuki part.

[IanFrancisco]

Oops, there I go spreading inaccurate info around again. Sorry! What Earl says makes sense to me, but doesn't that put more load on the two phases that have to work all the time? It seems it would be better to go with a good RR that has no problem keeping the voltage under 15VDC and no problem sinking off the heat/power generated by all three phases of the stator working all the time even when the lights are off. The Electrex unit has a much larger heat sink. It almost wouldn't fit on my bike, I had to use a Dremel on the holes in the ignitor mounting plate to move it over 1/4in. to get everything to fit right. I was going to use the Dremel on the RR but didn't want to make it unreturnable. Even on hot days running on the freeway with no lights that Electrex RR never seems to get very warm. Better check my battery to see if it's boiling dry...

[earlfor]

"but doesn't that put more load on the two phases that have to work all the time?"................. Not exactly. :-) That stems from the difference between a car charging system and the GS system. Cars match output to load, so loss of continuity of a phase in an auto alternator would mean the remaining two phases would have to make up any deficit. The GS charging system does not match output to load. The stator AC voltage increases directly with crankshaft rpm regardless of whether there is any load. The stator outputs 80 V AC at 5K rpm. It produces 40V AC at 2.5K and 16 V AC at 1k rpm. Load is designed to be aproximately the same as the average output of the stator at an average riding rpm. Go too slow for too long and you will drain your battery, Go too fast for too long and the battery will become fully charged. BUT, once the battery is fully charged, the stator still produces the same charging amperage. The excess amperage is shunted to ground. Two phases of the stator are all that are needed to maintain the battery if the headlight is turned off. The output of the 3rd phase is almost consumed entirely by the headlight. There is about a 2 to 3 amp surplus with the headlight on and a stock wattage headlight. (surplus depends on which GS model you have but it should be in the 2-3 amp range) The R/R having to heat sink away excess power puts unnecessary wear on it. Running the bike with 3 phases charging and the headlight off produces an excess current to be shunted that the R/R is not capable of handling for very long. Its a sure way to treat yourself to a new R/R every couple of weeks. :-) The way to get the greatest longevity from your stator and R/R is to use all the power that is produced except for about 1 or 2% that is used to charge the battery. You want the system balanced so that a minimum of power must be shunted to ground.
No shunting to ground, equals a cool running R/R and a nearly unlimited lifespan of the charging system.

Earl

Oops, there I go spreading inaccurate info around again. Sorry! What Earl says makes sense to me, but doesn't that put more load on the two phases that have to work all the time? It seems it would be better to go with a good RR that has no problem keeping the voltage under 15VDC and no problem sinking off the heat/power generated by all three phases of the stator working all the time even when the lights are off. The Electrex unit has a much larger heat sink. It almost wouldn't fit on my bike, I had to use a Dremel on the holes in the ignitor mounting plate to move it over 1/4in. to get everything to fit right. I was going to use the Dremel on the RR but didn't want to make it unreturnable. Even on hot days running on the freeway with no lights that Electrex RR never seems to get very warm. Better check my battery to see if it's boiling dry...

[IanFrancisco]

Thanks! The best technical description of the charging system I've read yet since browsing this forum!!

[earlfor]

Glad ya liked it. :-) :-) Yessir, burn up that extra fat. Put that bike on a diet. :-) Excess stator calories are worse than cholesterol. :-)

Earl

Thanks! The best technical description of the charging system I've read yet since browsing this forum!!

[earlfor]

Re: Rectifier ?

77 through 79 GS 750's used a separate regulator and rectifier. I believe the GS1000 for those years also did. You can use a combined R/R in place of the original configuration on your bike. All you need to do is remove the old single function regulator (or at least disconnect it) The cheapest solution is probably to get a Honda R/R on ebay. I would avoid the stock Suzuki R/R as my general impression of them is they are fragile.
(there are always exceptions though and some people have never changed an original R/R) If buying new, Ricks R/R's are about $40 less than their Electrex counterpart. Also, on cyclerecyle

http://www.crc2onlinecatalog.com/

there are various new R/R's for reasonable prices. (not cheap, but reasonable :-) )

Earl

My bike is a 78 GS1000 having some charging issues. I have gone through the bike once with the stator papers but pland to do it again as a precaution but it appears the R/R is bad. Does anyone know if a 79 GS1000s R/R will work on my bike? I know the Suzuki part number is different but I am wondering what the difference is. I believe the 78 used a seperate rectifer and regulator while the 79 (part number 32800-49140 if this helps at all) used a combined unit. I am just wondering as I can get a 79 one locally brand new for about 25 bucks! Way cheaper than an Electrix model.
It is my understanding that these go bad in phase 3 (lights on). If I CAN use the 79, is there also a way I can splice the phase 3 out of the system so the rectifier wont go bad (like the gentlemen did when he used the Honda rectifier in the posting on this site)?
Again, you people are awesome and all this help goes to show the love that we have for these machines! I will have piled WAY more money into this machine than it is certainly worth, but to me its STILL money well spent (but if I can save some thats great too!)

[beby99]

The way to get the greatest longevity from your stator and R/R is to use all the power that is produced except for about 1 or 2% that is used to charge the battery. You want the system balanced so that a minimum of power must be shunted to ground.
No shunting to ground, equals a cool running R/R and a nearly unlimited lifespan of the charging system

Hey Earl....nice explanation. 8) I understand what you are saying about
too much juice not going anywhere but how about the opposite? Say too
many accesories and not enough power? Obviously you end up with a
drained battery but what might this do to your stator and R/R?

Sorry Gutter for the highjacked thread

[Anonymous]

Thanks Earl, for all the great info. I will pass on this R/R then in favor of a Honda unit. Now my ? would be do I need to get the CX-500 one as indicated in the article here or are there certain ones that work better/are easier to modify than others? I am no electrical genious that is for certain, with the help of that article I think I could do this. I dont forsee myself riding without the lights on since it is technically illegal day or night so should I skip that mod if I go with the Honda part? Again many thanks to all of you! And Brett hijack away, I am an information junkie myself and Earl appears to have alot of it... haha.

[earlfor]

If you have accessories that draw more power than is being produced, yep, you end up with a drained battery. For charging system longevity, this is the best condition as there is minimal resistance, and low voltage/pressure to overcome. Draining a battery however is not good on batteries, so the battery will have a high wear rate if this happens frequently. (it causes plate sulfation and internal grounding) The answer is it doesnt hurt the charging system one bit.

Comment about batteries........... The R/R reads battery level as electrical pressure (voltage). As voltage increases in the battery, resistance increases. A battery in poor condition (worn out) will have a higher resistance at a lower voltage than a new one. Its false economy to save the $25 and not replace a marginal battery. In the long run, that will cost many times more in stator and R/R replacements.

Keeping the connections tight and clean, having a good battery and balancing the load to output in the charging system will keep it trouble free.

Earl

Hey Earl....nice explanation. 8) I understand what you are saying about
too much juice not going anywhere but how about the opposite? Say too
many accesories and not enough power? Obviously you end up with a
drained battery but what might this do to your stator and R/R?

Sorry Gutter for the highjacked thread

[Anonymous]

Bypassing the headlight loop on the charging circuit is easily done.

How is this done? I live in MA, so the headlight is required to be on ALL the time, I never shut it off.

[earlfor]

There are three yellow AC output wires coming from your stator. Two of them plug into the R/R. The 3rd wire from your stator(lighting circuit) is factory connected to a wire lead on your wiring harness. Rearward on the harness is a wiring lead that is connected to the R/R for this 3rd phase.
Disconnect the first connection from the stator to the wiring harness and tape it over. Disconnect the ending connection from the 3rd phase going to the R/R and tape it over. Connect a wire directly from the 3rd phase yellow wire of the stator to the AC input lead on the R/R.

The downside to this is if yo burn out your headlight with the system set up this way, there are still three phases fully charging and you are not consuming the power normally used by the headlight, so you will cook your R/R if you do not replace the headlight bulb.
(with factory wiring, this is not a problem because with the bulb burned out, there is no continuity on the 3rd charging phase)

Earl

Bypassing the headlight loop on the charging circuit is easily done.

How is this done? I live in MA, so the headlight is required to be on ALL the time, I never shut it off.

[Anonymous]

Thanks Earl. When you say you will cook the r/r if the headlight burns out and it is not replaced, are you talking about cooking it in an hour, a few hours, or many hours? Where my bike is stored I would notice the headlight being out as soon as I started it because it is dark in the garage, but if I was out riding and it burnt out I might not notice it until I got home. Like I said, in MA it is required to run the headlight at all times, so if the light burnt out I would replace it before riding again, so It would be pretty quickly that I got a new one. On the other hand, if it would fry my r/r in the matter of an hour or so I could be at risk and bypassing the light switch would not be worth it.

[earlfor]

As operating temperature increases with electronic components, lifespan decreases. It follows there is a temperature at which lifespan will be zero.
Stator output depends on engine rpm. So, If youre cruising the curves at 45 mph taking it easy in 5th gear, the output is going to be low,so with the headlight burned out, there will not be a huge excess of current being shunted to ground. If you're at the same speed, but in 1st and 2nd shooting the twisties, rpm will be high as will stator output. A new battery will accept the charge easier than an old one. An old R/R that has already endured being hot for a number of years will have less tolerance to a further increase in operating temp than a new one. I cant give you a specific time frame for how long you can expect to run in an overcharge condition without destroying the R/R. My best GUESS is you could 100% safely run for 3 or 4 hours. Probably be fine for the whole day. Beyond the day, I would not do it. If you do notice your headlight is out, usually you can just switch to the other beam. If both high and low beams are burned out, I would remove one of the yellow stator leads going to the R/R so there are only two phases charging.

Earl

Thanks Earl. When you say you will cook the r/r if the headlight burns out and it is not replaced, are you talking about cooking it in an hour, a few hours, or many hours? Where my bike is stored I would notice the headlight being out as soon as I started it because it is dark in the garage, but if I was out riding and it burnt out I might not notice it until I got home. Like I said, in MA it is required to run the headlight at all times, so if the light burnt out I would replace it before riding again, so It would be pretty quickly that I got a new one. On the other hand, if it would fry my r/r in the matter of an hour or so I could be at risk and bypassing the light switch would not be worth it.