Project "walrus" Yam XS 750

12.3 is marginal if the regulator is stuffed. Should be closer to 13V if it was a freshly charged battery. Suggest you charge it and see if you get good spark. In the past I have hooked up a car or boat battery with jumper leads just to test things http://www.dotheton.com/forum/Smileys/default/wink.gif
Tim
 
Re: Project "walrus" Yam XS 750

Ok tim!so you connect a car battery (running motor) directly to the minus and plus terminals of the xs battery am I right...then i will do it this way next time!

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Superb! :D then I will try it this way!

The PO told me that he thinks the rectifier is fried cuz the lights and control lights won´t come on (in all key position), he gave me a new unit, i guess I will try to connect the new unit to when I try the things you stated.

There is a malconnection too at the cables coming out of the rectifier (black cable came loose), could this also cause this ignition problem, i tried to fix it,maybe there´s still no connection?
 
Yes the cables and connectors are 40years old, there is probably more than one faulty connector. On my bike it would not charge, the rectifier was OK, the problem was just shitty connections that were worn out and corroded. The black cable out of the rectifier goes to earth. I hate electronics - it is more like black magic to me!!!!! In the end I just had to pay a guy to fix it http://www.dotheton.com/forum/Smileys/default/angry.gif.
Cheers
Tim
 
I personally ran up and down every harness with a multimeter and cleaned all connecting plugs with contact cleaner/small wire brush. Tested all loads for static battery draw and verified all resistances of components.
The joys of a 35+ year old bike. Nothing beats the sound of a triple though.

Good luck
 
Re: Project "walrus" Yam XS 750

Does any of you guys have a coloured wiring diagram handy in high res?would like to print it out to fight ny electrical gremlins...i yesterday dug out a spare loom maybe I will need it :)
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Re: Project "walrus" Yam XS 750

I have one for every model made in my manual, can send pics of your models tonight when i go by the garage.
 
Electrics probably just need a good cleaning - the connectors hanging on the left side of the battery box are usually subjected to battery acid early in the bikes life because of the vent tube there, so they will be corroded and not letting voltage through!
Did you try to hang a size 10 spanner on the alternator cover with ignition switched on yet? It should magnetize enough to hold the spanner.
Soon you will have a roaring triple!
 
Re: Project "walrus" Yam XS 750

Thanks data!will do!
I'm new to the 4stroke world so I keep learning everyday.
Alternator is left hand side am I right?
Will this also apply with my XS 850 electronic ignition?

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Re: Project "walrus" Yam XS 750

datadavid said:
I have one for every model made in my manual, can send pics of your models tonight when i go by the garage.
That would be great thanks!

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Ryan Stecken said:
Thanks data!will do!
I'm new to the 4stroke world so I keep learning everyday.
Alternator is left hand side am I right?
Will this also apply with my XS 850 electronic ignition?

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Alternator is right hand when sitting on the bike.
850's have same principle charging system, but i think they have unit construction reg/rec's.
 
Hi Ryan
When you sit on the bike, the alternator is on the right hand side and the ignition is on the left hand side.
The charging loom does not go up through the main harness. Four wires come out of the alternator and into the rectifier. Then the black and red out of the rectifier are your ground and positive.
The Yamaha Triples site has the manuals on line http://yamaha-triples.org/library/owners/xs7502d/default.asp
Regards
Tim
 
Re: Project "walrus" Yam XS 750

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Alright right hand side!

The PO installed the 850 ignition...I think the reg/rec is now a combo unit,it has two cable strings with plugs on it IIRC.

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Re: Project "walrus" Yam XS 750

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no nice and bright colors unfortunately.. i can scan it for higher res if you have any use for it.
 
Re: Project "walrus" Yam XS 750

datadavid said:
no nice and bright colors unfortunately.. i can scan it for higher res if you have any use for it.
that would be really nice of you!

I will hopefully get on the bike tomorrow and try the things you said guys.Already bought new ignition cables and spark plugs.

Is there a sure way to test coils for function with a multimeter (i read something about measuring the ohm figure)?
 
Hy Ryan
Not a pretty photo!!! Looks like the alternator cover has been off for a long time. There is not much that can go wrong with the rotor but there is a lot that can go wrong with the coils. In the alternator cover there are 2 separate coils. The inner coil is the energizer which works with the rotor to create the magnetic fields. The outer coil generates the AC voltage which goes to the regulator. You need to test wire to wire on both wires that go to the energizer coil and then there are 3 wires (from memory) that come from the generator coil, so you heed to test is 3 pairs of wires. For example W1 with W2, W3 with W1 and W2 with W3, if any of these are open circuit you have a problem. Use a multimeter on the lowest resistance scale. If 2 or more wires are open circuit then you need to fix them. The most likely point that they break is where they come out of the cover. Means you have to strip the insulation off at that point make the repair and then cover again with insulation heatshrink or tape.
Not fun, of the 3 alternators I have 2 needed repair at that point.
I have attached a PDF of the XS750-2D repair manual which I downloaded off the web for free - no copyright.
I have also attached a Mikuni carbi tuning guide which I have made up from copying a number of different documents and bloggs that made sense. I cannot claim any credit for the information.
Hope they help you.
Regards
Tim
 

Attachments

  • Yamaha_XS750_Service_Manual (1).pdf
    7 MB · Views: 421
  • Mikuni BS34 Idle circuit tuning.pdf
    667.8 KB · Views: 6,903
Ryan
If you have a digital multimeter then there is usually a setting on ohms where if you put the 2 probes together it beeps, meaning a closed circuit. No beep means open circuit, which is bad!!!
Cheers
Tim
 
Ryan
The attached snip of the circuit diagram for the charging circuit. It shows you the colours of the wires you need to test.
Cheers
Tim
 

Attachments

  • XS750 Charge circuit.PNG
    XS750 Charge circuit.PNG
    114.6 KB · Views: 1,102
Re: Project "walrus" Yam XS 750

Thanks guys just got my first box with rubber carb boots...the new ones are a bit longer than the stock ones...will this cause any issues (ebay item for my bike model)?
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