Newbie needs help with XS 750 wiring

[manas]

Hello everyone, I've been a DTT lurker for more than a year now and I've never posted. Just bought a 1976 XS 750 a few months ago and didn't really start working on it until two days ago.

I've heard a lot of good things about the XS750 (sound great, rides great) and a lot of horror stories about getting them to run perfectly. This is my first attempt at customizing a motorcycle so hopefully this experience doesn't leave me jaded.

The motorcycle did turn over (no start though) when I tried, which is good considering that the bike has been sitting all winter in a shed. So far I've removed my carburettor and taken off the air box.

Upon removing the side panels I noticed that the previous owner has apparently converted the points type ignition to electronic. I made this judgement because I found a box that says IGNITION UNIT and its made by Hitachi. Is this a good assumption then?

I also noticed that the wiring is pretty much everywhere and I have no idea where it goes or what it does. My main fear is pulling it all out and not being able to put it back together. However, I'll have to do something. As I see it, I have a few options :

1.Pull all the wiring out, try to make sense of it. Try to put it back together after I've made modifications to the bike.

2.Pull all the wiring out and also replace the retrofitted Hitachi/Yamaha ignition unit with a $200 Newtronic electronic ignition unit.

I'm looking for input on any/all of these things. Anyone with experience on wiring the XS750 or bikes in general is welcome to tell me what to do. I did read through the essential stickies on this forum regarding electronics and wiring. I understand some of it, and since I'm not *completely* retarded I should be able to figure things out after asking a whole lot of questions.

 

[teddpage]

Do you have a decent repair manual for the bike? A manual will usually walk you through troubleshooting different problems. There are a million different reasons why a bike wont start. Id check compression, check if you are getting spark. Then move on to cleaning the carburetors til they are clean enough to eat off of.

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[cleoncleon]

Hope these help..
I color code'd it all to the best of my futile abilities and in the end, got my buddies XS750 running..
Adding lights and Accesories should be easy after wards..

Top one is Wiring with some Light and Accessoires..
Bottom is a cleaned up version with alot less to look at..

 

[manas]

Re: Re: Newbie needs help with XS 750 wiring

Do you have a decent repair manual for the bike? A manual will usually walk you through troubleshooting different problems. There are a million different reasons why a bike wont start. Id check compression, check if you are getting spark. Then move on to cleaning the carburetors til they are clean enough to eat off of.

I bought a Clymer and gave it a good read. From what I understood and also the impression that I got from the previous owner was that motorcycle was start-able in warm conditions but refused to start at anywhere near cold (around zero Celsius or so).

I decided that I'd slowly begin servicing the bike instead of waiting around for summer. I'd like to figure out the wiring now that I've got the carburettor off. I just can't seem to understand what the previous owner did and I don't want to be in a situation where I've got everything working but can't turn the motorcycle on because I messed up the electricals ..especially the ignition system.

Should I rip everything out? Should I leave it in there?

 

[manas]

Re: Re: Newbie needs help with XS 750 wiring

Hope these help..
I color code'd it all to the best of my futile abilities and in the end, got my buddies XS750 running..
Adding lights and Accesories should be easy after wards..

Top one is Wiring with some Light and Accessoires..
Bottom is a cleaned up version with alot less to look at..

Man, this looks like so much help. Thanks so much cleoncleon. You wouldn't happen to have a clearer copy of that would you? I might take some photos of my bike to see if you guys can make sense of it.

Does anyone here have any experience with the Newtronic ignition system?

Also, I'd like to install LED lights at some point. In that case, does it make sense to try and salvage this or should I rip everything out and start over?

 

[teddpage]

If the bike supposedly started, then i doubt its electrical. Double check that you have spark. If ao clean the carb and set it to factory specs, then attempt to start it. Chances are the carb is just gummed up.

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[cleoncleon]

IMO, I would rip it all to hell and start over..
But, I tend to see this as normal practice when dealing with any bike older than 85', i do understand some dont and the saying "if it aint broke, dont fix it" does still have much merit.. it's all case by case though.. not everyones builds go the same.

Tear it out; it'll make your bike stronger, more reliable, 100x easier to trouble shoot, and cut those "racer" grams of weight too, if needed.. lol . And if it is worn enough, good chance it is.. you'll see some direct performance gains too.

Just get yourself some terminals/connectors and some 18G wire and go to town.
Of-course thicker gauge wire for grounds and what not.. But of that stuff, I bet you can just salvage that off the old harness.

As for the diagram, I have a bigger one.. Ill post that here.
But theyre all 'blurry'.. It took me ages to find someone on the internet with a diagram of the damn thing.. and so far, the same one still remains the only one i can find.. Forgot his name.. he was on the yamaha-triples forum..

Use this big one and just blow it up on the computer. Run back and forth from the guaest house garage to the desktop in the main house basement if you got too.. ;D

 

[cleoncleon]

The diagam is really good for setting up the ignition and charging systems up properly,
thats all the important shit..

Light and Gauges can be wired in very easily afterwards..

 

[manas]

Re: Re: Newbie needs help with XS 750 wiring

The diagam is really good for setting up the ignition and charging systems up properly,
thats all the important shit..

Light and Gauges can be wired in very easily afterwards..

Thanks a lot cleoncleon. I'll take your advice and diagrams and will report back in a few days!

I think what I'll do though is see if I can get the bike running again and then rip everything off. Since it's pretty close to running I might as well try.

Plus I don't want to rewire everything and find out that the engine or ignition unit needs work.

 

[teddpage]

Re: Re: Re: Newbie needs help with XS 750 wiring

Plus I don't want to rewire everything and find out that the engine or ignition unit needs work.

Always make sure the bike runs before you do any more work. Thats how i roll at least.
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[manas]

Re: Re: Re: Re: Newbie needs help with XS 750 wiring

Always make sure the bike runs before you do any more work. Thats how i roll at least.
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Thanks for backing that up Tedd. While I've ridden a few motorcycles this is my first time taking one apart, so its good to know that Im making the right decisions as I go along.

 

[afr00t]

I know this is an old topic, but did the wiring diagram help? I'm having trouble rewiring my xs750 ... Wish I can just pay someone to do it but there aren't any around

 

[Sonreir]

http://www.sparckmoto.com/harnesses

Just sayin'.