Author Topic: 79' Yamaha XS750 special not charging (Read 6316 times)

ThomasD883 · « **on:** March 21, 2012, 12:34:39 pm »

Really need some help, im putting this bike on the road at my expense for a friend. Got it cheap, rebuilt the carbs but its not charging. I downloaded a manual, but it does not have the same equipment as my bike. This un has electronic ignition and electronic reg/rec. The manual didn't cover that

. I'm open to any suggestions, opinions or offers for purchase

. please be detailed , im pretty dumb

. Thanks for the help. BTW, i should say i already replaced the feild coil .

ThomasD883 · « **Reply #1 on:** March 25, 2012, 08:33:33 am »

grcamna2 · « **Reply #2 on:** March 25, 2012, 06:46:22 pm »

That's the XS750 triple correct? how are you're brushes(if that year has them..)and connecting wires ? sometimes those brushes make contact in their cages or the connecting wires ground out in places..;any pictures ? you may have to get some service manual pages online to correctly test the electronic reg/rect. unit,or the easy diode tester, a battery powered continuity light that will light in one direction but not the other when connecting to the specific color wires.I may have a compiled Yamaha manual in storage that will give me the needed info & I'll check on it tomorrow...if you like; let me know before Mon.morning.

If there are any ground connection points where the rectifier mounts solidly to the frame those are good to check;sometimes the place where it is mounted(battery box) is attached w/ rubber grommets...and in that case I recommend that you attach a separate ground wire...or clean ALL the mounting points to shiny where they make connections to the frame.
I apologize...does you're frame/eng.# start w/ 1J7-3***** ? if so that's a XS750SE and doesn't have brushes. I think the Reg./Rect. assembly test procedure is the key.

ThomasD883 · « **Reply #3 on:** March 26, 2012, 07:52:35 am »

I would really like a manual, I'm going to be working on this for a bit. I do believe the latter half was correct ie. no brushes and need to test the reg/rec. Thanks for any help, I'm drowning. Also it is the triple.

grcamna2 · « **Reply #4 on:** March 26, 2012, 07:56:17 am »

Try Ebay for a manual & I'll try to look up the Reg./Rect. test specs from my Big multi-cycle manual..in storage & get back to you this afternoon.

ThomasD883 · « **Reply #5 on:** March 26, 2012, 08:12:22 am »

I should mention that im terrible with bike charging systems. Any detailed breakdowns you have would be useful. Thanks!

kirkn · « **Reply #6 on:** March 26, 2012, 08:23:04 am »

I have (most of) the shop manual in .pdf format. PM me with an email address and I'll email it to you. It's about 4 megs worth of 13 separate files, including a complete section on the electrics, including all testing and troubleshooting.

*EDIT* Just re-read your post and it looks like you have a manual, just not the correct one - mine may be the same one you already have. Hmm....

Also, there's a Yamaha Triples forum out there, same as this SOHC4 Honda forum. Seek it out, there will be MUCH more detailed help available. I was an active member there a few years back, when I had a '77 XS750.

Kirk

ThomasD883 · « **Reply #7 on:** March 26, 2012, 10:58:40 am »

Thanks kirkn, i pm'd you just in case. I was apprehensive to go for another fourm, but will try it as a last resort. Thanks!

grcamna2 · « **Reply #8 on:** March 26, 2012, 01:17:58 pm »

Thomas,
I went to my storage and looked at a Generic Chilton's that I could get my hands on easily from where I stood and it didn't have the info needed.I think you'll have to wait for me to dig past some of the other stuff for me to locate my O.E.Yamaha manual..it's brown & white.It was SO windy here today that I was leery of hauling out a lot of stuff for fear that some of it would blow away.I still enjoy repairing bikes..if I was to purchase one(I'd like to keep it if possible)and let you borrow it...would you send it back to me after you used it ? I could have it drop shipped to you;do you have the XS750SE 79' model w/ the ViN.# prefix that I mentioned earlier ?

Let me know...
Bill

ThomasD883 · « **Reply #9 on:** March 26, 2012, 01:41:35 pm »

We've got the wind too, having trouble opening the shop door ay work

. I definetly have the 79' xs750se, not sure of the vin. I'll get that as soon as possible. I couldn't expect you to buy the manual, I may have to bite the bullet, this was my best hope for human intervention as we have some of the best at the tip of your fingers. F'in thing , every time I start it its something else. Wah

grcamna2 · « **Reply #10 on:** March 26, 2012, 02:16:52 pm »

Thomas,
You're fixing the bike up for a friend for him to re-sell...so you may not need the manual after the bike is fixed,correct ? I'm asking because I found an O.E. manual on Ebay & I'd like to own it for future reference,it covers All years of XS750.There's a lot of those bike's out there and I'd like to have the manual to fix some of them later.They want $39.95 + shipp. for the manual. Do you want it ?

ThomasD883 · « **Reply #11 on:** March 26, 2012, 03:16:47 pm »

The whole of it is I am fixing it for a friend to ride, initially I wanted something bigger as I'm currently on a 650. Decided I like my Honda much better and after some talking, agreed to gift it to him. A float was sticking originally , then the rear caliper stuck, now this. Got them old bike blues.

is that manual a clymers or a factory? I've had times when the clymer didn't cover a lot of things, important things, and others where it just had generic stuff.

grcamna2 · « **Reply #12 on:** March 26, 2012, 03:36:38 pm »

Do you have the Clymer's now? This one is a Yellow O.E. Yamaha Shop manual & I'm sure it'll have any info you need for getting her on the road & running good.I have a valve cover gasket O.E. for the XS850..not sure it'll fit + the valve shims in different sizes if you wanted to do the complete job & fine tuning before gifting that XS750SE to him.I may even have an oil filter.I had a repair shop back 15 years ago and I'd like to start working on the side again;w/ the price of gas there are more bikes on the road...and I'm moving to the South to enjoy warm weather all the time.

ThomasD883 · « **Reply #13 on:** March 26, 2012, 03:49:02 pm »

I would definitely appreciate it, I have a self reliance issue, makes it hard to accept generosity. It's really low miles, hasn't been registered since the early nineties, and in fairly good shape. Just will not charge, thereby becoming a 500 pound lawn ornament

. Thanks again for the help, I was starting to consider looking at taking it too a shop

, oh boy

grcamna2 · « **Reply #14 on:** March 27, 2012, 10:01:53 pm »

It sounds like a Beautiful Vintage Yamaha

.

ThomasD883 · « **Reply #15 on:** March 27, 2012, 10:14:10 pm »

Only because of your help my friend

, no breaks on my end, only desire. It is a very nice ride though , very smooth acceleration.

grcamna2 · « **Reply #16 on:** March 27, 2012, 10:41:30 pm »

Thomas,
did you find out what exact model/year the bike is ? The book goes as high as a 78' XS750SE..but a 79' is an XS750SF;they couldn't be that much different.I'm sure the O.E. Yamaha book will give you the specs for the correct Reg./rect. test procedure.I've found that a battery powered continuity light is one of the best tools to use for those electronic units such as you have...from color to color,just use the positive tester wire to one color & negative tester wire to the other;it will light up or not..and then switch directions w/ the pos. & neg. wires on the continuity tester to those same colored wires on the electronic reg./rect. It lights up in one direction & when you swap + & - on the tester it doesn't light up in the other direction.Basically it's a diode test.

ThomasD883 · « **Reply #17 on:** March 27, 2012, 10:50:40 pm »

I've got the tester, I did automotive work for years but honestly without a visual reference I feel lost. I'm going through a big move with.family, very taxing and I really appreciate your patience. Not enough to go around man,

I will see it tomorrow and give as much detail as possible .

grcamna2 · « **Reply #18 on:** March 29, 2012, 07:21:43 pm »

Hi Thomas,
Did you get the book today ? I checked it w/ the tracking# & it showed it to be out for delivery..let me know what condition it's in so I can leave the man positive feedback

.

ThomasD883 · « **Reply #19 on:** March 30, 2012, 10:04:07 am »

It looks good, the spine is taped and there are some oily spots on the pages, but complete. Will get to it this weekend and post back! Thanks again

grcamna2 · « **Reply #20 on:** April 20, 2012, 05:27:52 am »

Hi Thomas,
How's she coming? did you get you're XS750 to charge yet ? I hope the book I sent to you has the information you needed.I'd like to help any way I can; keep me in the loop, OK ?

ThomasD883 · « **Reply #21 on:** April 20, 2012, 10:21:34 am »

Waiting on the cash flow to pick up for the reg/rec, seems to be the culprit. I hate being broke

grcamna2 · « **Reply #22 on:** April 20, 2012, 02:54:08 pm »

Do any of the ones on Ebay have a guarantee if they're NG ? You can get a seller who has a good return policy.. It may be a lot cheaper that way;I know salvage yards & dealers won't take returns on Electrical.

News:

Author Topic: 79' Yamaha XS750 special not charging (Read 6316 times)