already having a problem..

i just made a post a couple hours ago about buying a '77 KZ750, well i'm already having a big problem with it. when i went to pick it up at the shop, they were supposed to have replaced the battery on it but found out that the battery wasnt the problem... the rectifier and regulator were bad. they have replaced the regulator but haven't found a rectifier for that bike, and they're saying Kawasaki no longer makes them. they are calling a place tomorrow to order one IF that place carries / rebuilds them.. so basically i have two questions, one is if they can't find one, do any of you have one you'd sell or know where i can get one myself? and secondly how hard to come by are the parts for this bike? i love the bike already but it may not be wise for me to have it as my first one if parts are too scarce for it. thanks in advance

Duke396, Welcome. First thing you will want to do is to put your bike year/model in your signature. See the post at the top of each page in the tech section. You might also include your location in the event there is someone near who can be of help.

I don't know much about the 750 twin but if it has a separate regulator and rectifier, these are probably the same bits used on many models and readily available on eBay. I generally keep a few of each for spares for my personal and carb testing bikes. You can also buy a combo reg/rec and replace the old stuff if you like. Z1Enterprises.com sells them and they are pretty reasonable.

Buying an older bike can be either positive or negative for a learner. It depends on your attitude and willingness to learn how to work on your bike. If you want to ride and don't want to mess with mechanical/electrical stuff, then you bought the wrong bike. If you want to learn how to work on a bike, it will be invaluable. The older bikes are simple and easy to work on but if your goal is just to ride and not wrench, get a newer bike. Get a Clymers manual for your bike and look through it before making up your mind. It isn't terribly difficult nor does working on a KZ require a lot of special tools. And like I said, if you can hook up with a local member who can help, it will save you a bunch of money in the long run as many of the jobs a shop will charge you an arm and a leg for are not very difficult to do yourself especially with some good local advice.

Thank you for the quick response, and I'll be sure to put that in my sig.

Its not that I dont want to work on the bike, I really dont mind that part. Im just used to working on cars and dont know much about it yet.. My dad used to ride though and he is willing to help me. I was just worried that I wouldnt be able to find parts for it, thats all. I'll check out that site also.

I will be doing most if not all of the maintenance myself, but this particular problem the shop is supposed to be fixing for free if they can, because its where I bought the bike and they agreed to make it roadworthy before I left with it. Again thanks for your help!

You can use 78-80 750 twin parts and update it to the later (and simpler) charging system. You would have to replace the left side engine cover, the stator, the rotor, and the reg/rec, and it would be a good time to rebuild the starter clutch also (the infamous "While you are there")

If you are sure it's the rectifier you need, you can build one pretty cheaply. I'm only guessing it's a 3-phase (Steell: yes, no?).

If it's a single-phase, you can just use two of the three rectifier modules in this design:
www.geocities.com/loudgpz/GPZdiy3phaseRectifier.html

loudhvx wrote:

If you are sure it's the rectifier you need, you can build one pretty cheaply. I'm only guessing it's a 3-phase (Steell: yes, no?).

If it's a single-phase, you can just use two of the three rectifier modules in this design:
www.geocities.com/loudgpz/GPZdiy3phaseRectifier.html

It's the early style alternator with the coil, not the permanent magnet type alternator.

Duke, the guys who have responded to this thread so far are so skilled they could build you a rectifier - or a whole bike for that matter - out of bailing twine and chewing gum.

Me on the other hand, I don't know squat about squat. But I do know that the '76 and '77 twins had seperate regulators and rectifiers, and the '78-on had the regulator/rectifier combo unit. And yes, it's true that the seperate units are rare.

Now that *you* know that too, go to eBay and watch and wait. Call scrapyards that you find on the net, or even here in this site. Those are the cheapest options, if you don't want to make one yourself. If those options fail, try bikebandit.com or call around to dealers - though this is a pricey option.

Warning - watch out for eBay sellers who don't know your unit is not a combo! Here's a listing from a guy who does not know the difference. Do not buy this, it's not for your bike.

My advice is to buy a used one, however you can. Hell, buy 2 or 3. Stalk eBay regularly. Like George said, it's good to have a couple lying around... just in case...

steell wrote:

loudhvx wrote:

If you are sure it's the rectifier you need, you can build one pretty cheaply. I'm only guessing it's a 3-phase (Steell: yes, no?).

If it's a single-phase, you can just use two of the three rectifier modules in this design:
www.geocities.com/loudgpz/GPZdiy3phaseRectifier.html

It's the early style alternator with the coil, not the permanent magnet type alternator.

I assume, then, it is 3-phase. On those types of charging systems the regulator is usualy the weak spot.

The do-it-yourself rectifier will work for that type of charging system.


Someone reported an aftermarket combo unit for the 77KZ650 was available. That unit should also work on the 77 750 twin as long as the bike is 3-phase. It may require some wire splicing if the connectors don't match.

And... if you end up needing a regulator, and all else fails, there is a design for the regulator as well, on my site. But it's not for the faint of heart. The one you want is the alternate design at the bottom of the page.

geocities.com/loudgpz/GPZvRegExciteField.html

Post edited by: loudhvx, at: 2006/08/22 10:45

go look at the web sight "oregonmotorcycleparts.com and talk to tony. he is cheap and imo the best supplier of old bike charging system parts out there. he has a great warranty and i run his parts on my bikes. i beat my head in until i talked to him. i love the line in his web page that says " call me before you buy, i'de rather help you then sell you a part you don't need" that shows intergity and class to me. i never had a problum with his products and will certinally use him again for my kz1000 and gs750. he is to charging systems what z1enterprises is to everything else

I see, I see. You guys are really helpful, I'm definately sticking around here lol. Well I called the shop this morning and talked to the owner, and he said they had good news which is they were wrong... it did need a regulator which they replaced but the rectifier, they later found out the plug connection was bad so they cleaned it and it works, so I picked it up today and rode for a while till it started pouring rain... got soaked, and rode some more.

I love the bike... I almost didn't want to get one quite that old but it runs great except for a little sputter every now and then, probably because its only been cranked like once a week or so for the past year and a half, and not driven at all.

I'm going to take the advice you all have laid down... I definately want to start stocking up a few spare parts around the house for this thing, and I saw quite a few things over at Z1enterprises that I'd like to have for my bike. And I'll check out the oregon site if I have any more trouble with the charging system, or I may go get a combo. The z1 website does list one for the 750.

I appreciate the help, I'm learning this stuff as I go.

Post edited by: Duke396, at: 2006/08/22 21:37

Post edited by: Duke396, at: 2006/08/23 04:13

Good to hear Duke!