XJ 750 Not Starting

I have a 1982 Yamaha XJ750 Maxim. I have replaced the Carbs, battery and solenoid in it. It ran for about a week reallly good. One night on my way home from work at a stoplight in downtown it just randomly died on me and wouldn't start back up. I had to jump start it to get it home and then it hasn't started sense. On my way home though after I got it jump started the warning check started randomly happening. It happened 2 times during the 4 mile stretch of road to my house. Can anyone help me diagnose what is wrong with it? Did I buy a bad solenoid, is the regulator out of it. I"m totally confused and lost at what to do. I have a very mechanically inclined brother and he seems to be totally confused at whats wrong with it too. Any help would be greatly apprecited.

 

Replace the Fuse Panel.
Check the Alternator Brushes.
And, ... a whole lot of other things.

Measure the Current at the Battery with the Bike running at 2000 rpm's.

You should get a reading of 14.2 -to- 14.5 Volts.
If your Charging System is healthy; we'll do other troubleshooting.

The Fuse Box is the Number-1 cause of problems.
Alternator Brushes too short a common fault.

 

Well,
I don't have a fuse box I don't beleive. All the fuses are the ones that are on cars, and are located under the seat and they are all connected in the middle. If I'm not looking in the right place please let me know.

Thanks

 

Adding Information to my previous Post. <>

When I put the key in and try to start the bike up it Sounds like the solenoid sparks and then the display goes blank and won't come back on for a couple of hours.

I don't know if this information helps any diagnose the issue im having with my bike, but I figured it was a shot.

Thank you

 

check all the connections sounds like a loose connection positive or ground i see alout of cars with a bad battery connections when you hit the starter it goes click then goes dead when it does it next time leave the key on go thru all the connections see if you can find it .

 

Begin with the Basics.

See if there is enough power in the Battery to crank the Starter.

Charge the Battery.
Have the Battery "Load Tested" (for free) at AutoZone.

You need the Battery to supply "Cranking Amps" to Start the Bike.
12 Volts will make the Lights come on.
You need Amps to get the Starter Motor to crank the Engine.

 

I went to Sears today and the the battery tested. It failed of course so they gave me a new one because I had a warranty on mine. I got home put the battery in after charging it and it started right up.

I put a multimeter on it after I put the battery in and Idled it and the multimeter only read 12.76.

So is the alternator/stator bad?

Thanks for the help.

 

like rickomatic stated. you have to rev the motor to see what the charging is doing.

at an idle, most bikes run off the battery as the charging system isn't sufficient to run everything and charge the battery. usually around 1500 rpms the charging system starts kicking in. the higher the rpms. the higher the voltage. so you want to check the battery at 2000 rpms. and see what happens as you rev the throttle.

don't know about others bikes. but mine don't hit 14 volts untill 3200 rpms. 14.5 is the highest volts.

 

Note too the upper end. Your rectifier/regulator does two things, it rectifies AC current from your alternator into DC current (like Rick stated, at 2000 rpm) and regulates the voltage (I'm not sure what spec is...but def it should stay under 15 V) when the bike revs.

Snowwy, hopefully someone will come along and let you know if your not getting up to 14 V until 3200 rpm is unusual, but I know my 82 XJ750RJ makes 14 or so V at 2k rpm just like Rick says.

 

i could be wrong about the rpm. it was the first thing i checked when i was trying to get it running in the first place. about 4 weeks ago. it works and that's all that matters to me. LOL. cruising around town to me is between 3k and 4k anyways. so it's all good.

 

I tried it having my gf Hold it pretty well past 3000 while I checked the multimeter and it still sits at 12.5-12.7. Any suggestions on what is going on? Regulator, Stator/Alternator?

 

alternator brushes or the plug from the alternator, it's 3 prong and the wires are all white cloth covered inside a black plastic sheath, look around the battery

 

I've seen this posted before on this site:
http://www.electrosport.com/technical-r ... iagram.pdf

 

I just purchased a used Stator for my bike considering I beleive thats the problem. Now the issue is I have no clue whatsoever about where the thing goes or how to install it and I sent the money for the XJCD, but as I was reading people are saying it takes about 3 weeks. Any way someone can send the the diagram on how to replace this and any extra information I need to know. Like do you have to do anything special besides plug the cable in and put it wherever it goes?

Thanks

 

The stator is behind the cover on the left hand side of the bike that has 3 allen head bolts on it. The wire for it runs up near the rear of the airbox. It has a 3 point connector. You can find where the wire starts at the stator cover and trace it back to the connector. Disconnect it and pull it out so it is not going to get hung up when you pull the stator out. When you take the cover off all you should have to do is wiggle it back and forth and it should pop out. If you do not pull it straight out it can bind up and get frustrating. When you get it out, the "new" one you bought will go in the reverse order in which you took the old one out.
Just make sure you don't do what I did when I took my cover off to polish it. I didn't get the wires tucked into the grommet on the cover properly and I pinched my wires and ended up having to put a diffrent stator in because it cut the wires.
All in all it is not a very difficult job. If I can do it most anyone can. Good luck!

 

^^^^ What he said...especially about the wires not going into the grommet and getting cut. That's EXACTLY what I did.

Just curious, how did you determine the stator was your problem?

 

Well I work at Sears. So when I returned my battery to the auto center they talked to me on reasons why the battery would fail and other possible issues. Well when I got back on the forum and I read about the Multimeter and the voltage it should push out I tried the bike in first gear and neutral while keeping the RPM's up while I had a friend hold the multimeter on the bikes. After it constantly read 12.76 I Called my brother who owns a Harley Davidson, and who has rode a motorcycle all his life and he said Replace the Stator and if that doesn't work then its the voltage regulator. I figured for $37 bucks on ebay the Stator really wasn't a loss. So I really didn't do any technical work besides the Multimeter. I'm completely honest I have very little mechanical skills. Give me a computer and your issue and I can fix it. Hand me a Hammer and nail and I give you a puzzled look! But considering the details you guys give out, I'm definately sure I can replace and work on my bike. I can't beleive how knowledgeable and Kind everyone on here is. Usually when you ask for help on a forum they laugh because you don't know anything, but I will replace the Stator When i receive it and if it doesn't work I will surely be posting again.

Thanks For all the help as Always!

One other issue I am having with the bike is when I turn on the highbeams the dash lights go out? So probably a connection issue some where?

Any help is appreciated thank you.

 

I agree...everyone on this site is sooooo knowledgable...just about everything I've learned about the XJ's I've gleaned from this site. Including the link I provided earlier. When you are troubleshooting any problem, ESPECIALLY electrical, it will pay to be METHODICAL about solving your problem. Don't be just another parts changer.

I had the same situation as you, but the cause wasn't my stator failing, it was the wires that were cut when I put the alternator cover on. The link give you a step by step to help pinpoint your problem. I suggest you use it...even if you are right about the stator. That way we don't see an aggravated post tomorrow about why the the stator didn't fix it. If you don't, and changing the stator doesn't fix it, you'll be looking for a new regulator...then TCI...and you might find out it was your alternator brushes...or a bad connection somewhere, melted plug <- you get my point. Be methodical. Plus...that stator could be bad (rebuilt ones run around $150) so if it doesn't fix your problem, how are you going to be able to tell the difference between your "new" stator being bad, and the stator not being the problem in the first place (or worse...the "old" stator wasn't bad, but the "new" one is and now you have two problems)

 

I'm not trying to be a parts changer, lol. I'm not really sure where the alternator brushes are? I have very limited knowledge of anything mechanical. I'm still waiting on the xjcd so at the moment I have no clue where most of what you guys are explaining are at. That's why I just went ahead and bought stator considering the situation. To be honest I thought that the stator and the alternator were the samw thing. Pease correct me if I'm wrong.

Thanks for any help!

 

No worries about limited knowledge, that's why you need to ask plenty of questions. If you don't understand what people are talking about, use the little quote button on the top right...then follow it with "what?". We're here to help.

Wanna provide a link to the completed ebay listing (so we can see what you got)? The stator is a PART of the alternator, and is located under the alternator cover. It COULD be the problem (when I described my earlier issue, I replaced mine because the wires seemed diffcult to fix, and I had one lying around).

Did you check that link out? If you have a multi-meter, you should be able to follow those directions. If you have any trouble with it, just ask. It isn't specific to XJ's but it does have some good info and mentions Yamaha specific wiring. Also, get a Haynes manual - it costs less than your "stator." Try that link out and report back what you find.

 

Ebay50404&viewitem=&sspagename=STRK%3AMEWNX%3AIT

Here is the link to the stator that I purchased on ebay.

Thanks.

 

What? Sorry I'm a bit confused at the location I took the cover off the left side and it looked to me like the regulator. Here is a side picture of my bike hopefully my epic paint skills will help

 

That is the alternator cover...the rectifier/regulator (one unit) looks like this :
http://cgi.ebay.com/ebaymotors/1983-XJ6 ... ccessories
and is next to your TCI.

The stator fits around the rotor that is in that housing. Did you do the electrical diagnostics?

 

I have not yet done the Electrical Diagnostics. I will try and accomplish that this weekend. So just to make things clear. The cover that im pointing to on the Bike is where the stator goes?

Thanks

 

Yes that is where the stator goes

 

I was unable to complete the Fault Finding Flow chart due to the section that starts with Connect the RED lead to battery (-). I was unable to trace and find where that wire goes.

Also while doing this test my fuel light came on and I have a full tank and the Fuel Petcock was set to On.

Can someone please explain how to get past that part in the flow chart.

Thank you!

 

ManBot:

Look at the Face of the Alternator Rotor and see if the two Brush Contact Orbit "Tracks" look unusually dark.

If the Orbits look like they have been scorched by the Arcing of short Brushes.
Replace the Brushes.
Treat the Orbits to a resurfacing.

With a very light touch ... use 800 or 1000 and "Wipe-off' the burn mark.
Wipe following the Orbit.
When you get done.
Cover the tracks and your wipe-off work-scratches with 2000

Finish with Polishing Compound and a T-shirt.
Polish-out and swirls or scratches left-over because where-ever there is a scratch will arc and begin the process of scorching the Orbits all-over again.

 

I'm not sure if you've solved this yet, but:

If I remember correctly (I'm out of town right now and can't look at my bike) you are on the wrong path. There are 6 wires coming off your regulator/rectifier (RR) so you go to D. And yes, you have a RR. EDIT: There are 7 wires, 3 white, and a red/black/brown/green

What Rick is telling you to do (kaetalumin is the one with the problem) is general maintenance that will be good for you in the long run. If you know nothing of the charging system, then you can check the brushes just like any other INSPECT item on the maintenance schedule. But you have a charging system issue, and stepping through that flow chart should get you to pin point it so you don't waste time and money on parts that are good.