Bike won’t even turn over?

I bought an ‘82 XJ750 a few months ago that I’ve been trying to fix up. I’ve gotten it running but yesterday after running it a bit and it died it wouldn’t start again. No clicking, nothing. Today I got it to turn over once but that’s it. Every time I push the ignition button the headlight dims cause it’s pulling power but that’s it. Any ideas on what the problem might be? All fuses are good and all lights and display come on no problem.

 

Oh and the battery is good, and the starter relay reads 12+V across it.

 

make sure the bike is in neutral, then use a large screwdriver, or the like , and short it across the two large terminals on the starter solenoid.
if it spins the motor over ,then this eliminates the battery and the large wires from the battery to the starter moter , and the large wire black earths.
if it does'nt spin the motor then the fault is with one of the above, or the starter solenoid

 

You might want to pull the spark plugs out and make sure you don't have a cylinder full of gas & hydro locked first. With the plugs out put it in gear, 3rd or 4th, and try turning the rear wheel to safely pump out the gas. Yes it will make a mess but not as bad as if you do it on the starter & spark a fire.

 

What does the battery voltage drop to when you press the start button?

 

Sounds like the starter solenoid. They are cheap I usually buy two so I have a spare .

 

Just under 12 V.

 

It reads 12V across it…

 

I went out a few days later and it turned over no problem.

 

Check your oil. I bet the sump is now overfull and contaminated with the gas that was filling the cylinder. The "oil" will be REALLY thin and smell strongly of gas.

 

That’s not cool. My first thought is bad battery.... once again wouldn’t be the first time I’ve seen new batteries that were already bad.

 

Even if it reads 11.57V across it? I just tried it again and it turned over no problem a few times, then died, then back to not doing anything.

 

Okay, now I have to agree with @hogfiddles , it sounds like your battery is the culprit. Sometimes when they are dying but not quite completely dead they will have enough energy to give you a few turns but not enough to continue. It also sounds like you have some other issues with the charging system that might be dragging the dying battery down with it. Not common as these bikes have very good, robust charging systems. But also not uncommon either.
Take your battery to an auto parts place, most of them load test and charge the battery for free. Then check the output from the alternator after you get the bike running on your freshly charged or new battery.
And yes, even if it reads 11.57 volts. That is not a healthy battery. These bikes will operate the starter with a sick battery but it will drag the voltage down to where the ignition system will not fire but still will turn on the starter, for a little bit. When your battery is that sick you can have starter or you can have ignition but not both.

 

Yes, load test it.

 

The solenoid can get corrosion inside , I had one would crank a few times and the nothing . I could tap on solenoid with a screwdriver handle and it would work . I replaced it no more issues , I took the old one apart and it was pretty nasty inside. If your familiar with old Fords the starter solenoid would do same thing no crank issue. Solenoids are cheaper than replacing batteries.

 

I have a simulator issue . no crank. 2.5v across solenoid terminals when starter button pushed.
With starter removed, 12.46v at starter terminal [cable] when button pushed.


Bike bat. Fairly new,[not cheap] always shows good v.
Starter out: zapped with bike bat.- nothing. Zapped with car bat. -turns.
Take apart install new brushes, clean, and goop. Zap with a charger to test- spins,seems good.
Reinstall – nope. Took out again to trouble shoot.


Is this normal ? I don’t think so, 12V across start term. And casing. Notice the casing is not grounded.
Bike bat. At 13.2v jumping starter – 2.7v at term. And ground casing
hitting it with the charger, it seems to work fine. It wants amps.
Still working on it. Thought Id post what I did to my yamaha here,.

 

If your starter works when connected to a known good power source, battery & doesn't when connected to the bike battery the problem is the bike battery. Have it load tested at an auto parts place.

 

car bat. turns it much slower than the 200amp charger [fast charge]. if it is the bike bat. then it's a sudden failure - no warning.

 

That would be normal as the starter electrical path is through the positive brush, through the windings, through the negative brush to chassis. So the 12V says there is a path to chassis, it doesn't say for sure it is as mentioned and could be directly to ground at the starter post if the insulator was damaged or incorrectly assembled. However, in the latter case that would mean nothing but sparks if you connected the battery ground to the starter chassis with 12V connected to the post

And to the OP 11.57V across the solenoid would just mean the solenoid is not engaged and that the starter is providing a ground on the low side. It doesn't necessarily mean the starter is good, or the solenoid is good.

This is a really good link from the how-to instructions for starter troubleshooting

https://www.xjbikes.com/forums/threads/how-to-test-your-starter-circuit.7828/

 

update for those with a similar issue. it was the battery.
mighty max 18 months old. showed 13.4v , apparently no amps.