Started all week, now no start.

Hello guys,

Just picked up my xj 750 maxim 1982 last week. Drove her all week, and she started up just fine, no choke. Parked her overnight last night and woke up this morning to take her to work and now all she does is crank and crank but wont turn. wont even catch a little bit. Went to the auto parts store to buy some starting fluid hoping against all that maybe just maybe she would try to catch, nothing. I feel as though its electrical, like something is preventing her from starting. Any ideas?

 

Probably your battery. A bad battery can have enough volts to turn the starter but not have enough to create a decent spark.

If you have a volt meter you can test the battery. If the volts drop below 9 when you are cranking then your battery is probably shot.

 

^^^ yep

Battery voltage

 

bad battery or bad charging system. you may be able to bump start it to test charging voltage, or jump start it with car battery do not have the car running.

careful with the starting fluid it will foul your plugs if you try it to much and if you have pods have a fire extingusher near by a back fire will ignite the fluid on the pods

info on charging system and testing in this link
The Ultimate Relay, Switch, Sensor, and Diodes Guide

battery at rest should read 12.6 volts after charging and with bike running voltage should rise
* 2000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all models except XJ700-X and XJ750-X)
* 3000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all XJ700-X and XJ750-X)

 

thanks guys, i have a sneaking suspicion it is, the PO said he needed to replace the battery, and he has a trick charge connector permanantly attached to the battery terminal. It might not be charging when the bike is on, not sure but will need to diagnose that.

 

read the link I posted is all the info you need. way down near botom.
you need a voltmeter a multimeter a cheap one for 15 to 25 bucks.
walmart has a couple in the 25$ range and cheap battery.
pick up a trickle charger for you bike too

get bike started with a jump start . hook meter to battery first read voltage jump start it check voltage at 2000 rpm it will be good in spec or bad out of spec.

if charging is out of spec your battery may still be good

 

If it does turn out that the charging is out of spec obviously remedy that, brushes are the first place i would look after a little more voltmeter diagnosis, be sure to charge the battery up nice and slow then retest it to see if it is in spec or not. Reason I say nice and slow is most people I see hook the charger up, crank it up to the highest setting and leave it on just long enough to start the vehicle/bike/whatever. It is much better for the battery to charge nice and slow over an extended period of time to insure full charge state. Then the full health of the battery can be evaluated. There is a way to figure out how long and what amperage to charge a given battery based on its amp hour rating but it alludes me at the moment.

 

does it have any gas in it ?

 

Update #1 - got out the auto jumper battery pack on the bike. It back fired twice. sounded like a gunshot, not good for this prissy neighborhood I live in. still didnt try and actually catch, just sat and tried to start... yes there is gas in it. I dont have my volt meter with me at this apartment, its in my trailer. any other ideas? I can diagnose and see if its getting spark or not...

 

for what its worth, I think this bike has been rewired..

 

if it backfired it will start. pull plugs see if they need to be cleaned

 

also I sprayed starter fluid in it, it has to be the spark... Just ordered a spark plug tester

 

Backfiring...is the firing order correct?

 

1) Why should I not have jumper cables attached to a running vehicle?--->"jump start it with car battery do not have the car running."-XJ550H

 

Start you own thread please.

 

You got a boom. It's not the spark. No spark, no boom.

We need to back waaaaayyyy up.
What has been done (by you) to the motorcycle since you bought it?

Have you had the battery tested as requested?

We can't help you if you can't help us.

 

Hey sorry guys, I just started a new job and battling the LA traffic has left me with little time to diagnose what is going on with this thing. I have yet to do any further diagnoses yet as i need to take an hour and a half round trip to my trailer that has my tools in it. I will go grab my wrench and socket set, battery charger, and multi-meter, and a few screw drivers. Anything else that i might need? maybe soldering kit? I dunno, I just hate making multiple trips.

It back fired when I put the battery pack jumper on it, but I cant truly be certain that the jumper pack is giving a constant uniterrupted stream of 12v power, I have never used it before and its also one of them crazy phone charger things. It clicks and what not when I hook it up to the battery so I am just not confident on its ability yet. I will make a trip out to the trailer today.

 

My suggestion is for you to slow down then. Strating a new job is stressful enough. The bike can wait until you're under less pressure. Fixing things while under a time-constraint is bad enough; add the extra stress of a new job and a bad commute....it's better to wait until you have more time.

 

OK. Here's another update,

Got the the multimeter on it and it read 11.5 volts engine off, when key turns to on position it drops down to 11, when cranking it drops down to 10 and change. got the spark plug tester out and it was getting spark. not every time i cranked though. Not sure what is going on there. after about 20 seconds of diagnoses the battery conked out to 6-7 volts and it wouldnt even turn the starter. Putting battery on trickle charger tonight. will test out in the morning. The battery jump pack from amazon was a pos as i hooked it up directly to the + and - wires and it wouldnt even turn the headlight on. Not 100% sure what to think since i was getting spark, but it may have been getting it intermittently im just not sure. Hopefully a full charge tonight will shed some light on this tomorrow morning.

 

Plan on replacing the battery.

 

update #2. placed battery on trickle charger for couple of days. got out there tonight and hooked the battery up. battery was reading 13 volts. placed battery on bike and was getting 11.7 volts while cranking. Spark plug tester indicated spark was received. might not be getting spark on one plug. not 100% sure. its hard to hold everything and and press starter. Bike will occasionally backfire. sprayed starter fluid in airbox. nothing. this is blowing my mind, its got vapor ether going into the airbox and spark, it should be starting and running on ether if nothing else. I am so confused.

 

nobody ever said "i wish i had my old spark plugs back"

 

fuel is leaking out of the breather tube by the gear shifter. fuel in the crankcase. What is the diagnosis?

 

Float needles and/or levels are bad. Carbs should probably be refurbished.

Recommissioning these bikes takes patience time and some $$. You are methodically checking things off the list. Don't give up.

 

Homework time.

The Information Overload Hour

 

Ended up being the coil. Got it replaced, bike is running great again.

 

That does not address fuel in the crankcase though..... make sure you tend to it before either the engine seizes up or it blows up.