XJ550 Won't start. It was fine last week.

Hey folks I have a 1982 xj550 maxim. Someone gave it to and I fixed and It was running good, I tried to started today but it won't fire up. After a while trying to fire it up I had like a big explosion ( really loud) then my battery died, so I charged the battery and tried again and had another big explosion. So I thought maybe a have an electric problem, I was going to check the spark when I realized I have spark with the ignition off. So I don't really know what's wrong with that and don't know what to do.
If someone of you guys can help I'll be very grateful. ( English is not my first language so I'm trying my best)

 

how have you concluded that you have spark with ignition off,? do you mean the ignition is still "on" when key is turned "off", or something else?

 

If it ran well last week the issue should be minor. Perhaps the petcock was left on "prime" or the petcock is leaking and flooding the engine. Pull a plug or two and check.

 

Actually I remember I left the petcock on prime and was leaking a lot.

 

Remove the plugs, dry out the cylinders, replace the plugs, STOP THE LEAK and the bike will / should start. This is a fuel issue that is common with the XJ's. Check for fuel in the crankcase.

 

Thank you so much.

 

I pulled the spark and as soon as we touched the spark plug to the engine it sparked with the ignition off and on.

 

i would'nt worry about that, its probably just a charge left in the coils , after unplugging

 

Okay, thanks

 

So I'm back. I ended with dirty and plug carburators so I rebuild them. I put everything back Together and tried to start the bike but SURPRISE I don't have sparks. I checked the coils, ignition switch, I also updated my fuse block and checked the kick stand safety mechanism, I also have a good battery voltage. I don't know what else I can check. Please HELP.

 

did you turn the kill switch back to run?

check for voltage at tci on the red wire.
make sure battery is good and fully charged.
do a voltage drop test on battery hook meter to battery check voltage then press starter button see what the voltage drops to.
what is resting battery voltage and voltage drop?
a 550 will turn over well and still not start.

check your work on the fuse block replacment make sure you have voltage on both sides of the fuses

 

Yes, I did turn the kill switch back to run.

I also checked the voltage at tci on the red/ white wire. The battery voltage when resting is 12.5 and I will check the voltage drop. On the fuse block I checked the ignition wire but I'll check the rest of them.

 

what voltage did you get at tci?
could be the kill switch and related connectors are dirty and need to be cleaned.
test tci voltage with connector unplugged this may help see if you have voltage drop from fuse to tci. which would indicate dirty poor connections from fuse to run/kill switch and to tci. test points along the way.
at fuse
at connector to kill switch
at tci
and at ignition coils
all should be very close to battery voltage.

have you ohmed out the coils and pickup coils?

most important is check work you did from when it ran to now.
that is where any changes were made

 

I'm here again.
Voltage at tci is 11.79
Battery voltage 12.75
Battery voltage drop 11.45

I tested :
At fuse
At connector to kill switch
At connector to ignition switch
At tci
And Ignition coil also pickup coils.

All good and close to Battery voltage. I checked the fuse block all good.

So the newest thing that I found was:

1- Coil wire #2 is spark weak or decent spark.

2- Coil wire #3 spark decent.

3- Coil wires #1, #4 intermittent spark and after cracking when turn ignition switch off i
I can see a little spark.

So right now I don't what's really wrong. Coil?

 

unscrew the plug caps and trim back the spark plug wire 1/4 inch . the plug wires can corrode.
measure resistance of plug caps and plug wire end to end on each coil

Pick-up coils:
650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
Ignition Coils:
Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

how old are the spark plugs

 

I don't know exactly how old are the spark plugs but I'm testing with a new spark plug

 

I checked and I don't have any resistant on the spark plug caps. So that mean they are bad?

And I tested the ignition coils again both of them are resting good on the primary side but the one that's connected to cylinder 1&4 is showing nothing on the secondary side. That means that one is bad?

 

they read 0 ohms on caps? are the original equipment or replacments?
you should also test the other caps.
xj4ever sells replacments both oem and aftermarket caps

if 1 coil pak tested good at 11k ohms and the other tested nothing it is bad and you did the test correctly.

 

I will check I may have a good ignition coil for position 1 and 4.

it could be you have bad wires and could replace the wires using splicers and new wire.

 

Yes, all of them tested 0 ohms and they look original.