No idea why my bike isn't starting... need help

So this is what i've done in ORDER, and this is what's happening

(1982 XJ 650)


Measured valve clearances
Replaced 1 shim, put it back in with the shim tool i purchased from this site, done.
New spark plugs
New oil
New oil filter
New front brake pads
Took apart and cleaned the carbs, checked all floats/needles, cleaned more, etc (sprayed carb cleaner throughout each fuel jet on each carb and it went through perfectly, through all 4 carbs)
Measured the float bowls, all adds up, etc.
Did the bench sync - tweaked some of the screws so that the valves on the carbs would be open at the exact point they need to be, idle screw adjusted etc

Was just charging the battery, which i'll probably let it charge more.

Put it all back together. Fresh gas in the tank. New fuel filter, new petcock from last year. Put the petcock on the "ON" position, then tried reserve. Put about 1.5 gallons of gas in the tank. Left it "ON" for about 30 seconds, choke all the way, and the bike won't start. Tried it in reserve, still nothing. Then it made a weird noise when i gave it some throttle like it was trying to turn over but couldn't and then when i tried again the way its SUPPOSED to start up without the gas, i pushed the starter and it backfired through the exhaust and made a "BANG" noise for a second (I thought my dad dropped something but i asked him and it was the bike backfiring) and it still didn't turn over.

No idea what's wrong.

Last year it would start but the carbs werent synced right or something because it would idle around 900RPM and die out, and when i turned the throttle it would sputter etc before revving. Then when it would die out eventually i couldnt get it started for like 30 minutes after it would sputter and die out. Now it won't even start

 

put the petcock on prime to help make sure you get some gas into the carbs before you try and start it. on and res are both vacuum operated so they are only letting gas into the carbs when you are cranking the motor.

Get the battery fully charged. the spark on these bikes tends to be on the weaker side and without it being fully charged you are going to have a hard time getting it to fire.

 

I have an aftermarket petcock. PRI is essentially the same as RES on my petcock. It has Off, on, and RES.

Also, i may have put the wrong sequence for the spark plugs. Can someone help me understand what order they're supposed to be in? On the left side of my engine i have #1 and 2, and on the right side i have 3 + 4 in that order

Just looked at the coils. Coil 1 is 1+4 (longer wires) and Coil 2 is 2+3. (Shorter wires) I have them on so that 1 is on the far left spark plug, then 2 on the left, 3, then 4.

I'm assuming that's correct? The plugs don't reach any other way, 1+4 have to fit on the ends and 2+3 on the insides??

So i'm assuming it has nothing to do with that.

 

Hold on; you click the starter, and... The starter is spinning, but the engine isn't starting? Or just no noise?

Have you tried push starting it?

How far out are your idle mixture screws? Try doing half choke and pushing the throttle, and try push starting. If you can just get it started and running once and get a feel for it, you can troubleshoot a lot better.

Have you checked for spark on all four?

Have you ever done a compression test?

How is your air filter?

(And your spark plugs sounds correctly ordered, it's pretty straight-forward on this bike.)

 

as far as the coils go

This is the typical ignition circuit wiring for these bikes:

- the ignition coil for the #1/#4 spark plugs is mounted on the left side of the bike, and has the solid orange (ground) wire and the red-with-white-tracer-stripe (hot) wire input leading to it.

- the ignition coil for the #2/#3 spark plugs is mounted on the right side of the bike, and has the solid grey (ground) wire and the red-with-white-tracer-stripe (hot) wire input leading to it.


Note that for each coil, it does not matter which of the two plug wires goes to either of its cylinders, since a signle coil sparks both of its plug wires at the same time. So, for instance, the #1/4 coil fires both the #1 and the #4 plugs at the exact same time, and it does not matter which of the plug wires (from that coil) goes to the #1 or the #4 cylinder.

 

The bike attempts to start, but doesnt turn over. Starter makes noise like it's supposed to.

I didn't touch the mixture screws. The bike ran previously, just not ideally. I'd like to have it running before tweaking them.

All four get spark.
Compression checked out fine when i ran it last week.
Air filter is fine, clean, etc.

I'm going to ASSUME the battery doesn't have enough juice to get the engine to turn over, so i'm letting it charge and will try again in the AM.

The bike made a rev sound when i turned the throttle before the engine turned over, liek it was just about to turn over, but didn't.

And then a few attempts later it made a backfiring noise, still not turning over. (The start is making the sound to attempt to start, but the engine isnt turning over, and then it made a bit of a throttle sound, and a few attempts later, same deal, starter is down, attempting to start, nothing, then BANG, backfiring)

What's up with that? Maybe it wont start until i get the battery nice and energized, but why backfiring?

 

definitions
turn over - starter spins the motor
fire - spark ignites the fuel mixture and the motor turns under its own power


does it backfire when you let off the start button. This often happens because the battery doesn't have enough juice to turn the motor and supply enough power to spark the plugs. when you let off the button the motor spins a bit on the momentum it has and the bike now has enough power to spark the plug. when it does that with the fuel mix headed down the pipe from trying to start it and likely being a little flooded you can get a backfire pop.

 

Measure battery voltage when you are attempting to start that bike. If the voltage drops below 11 volts your battery is either not fully charged or is junk. The ignition system will not work properly if at all below 10.5 volts and when you let off of the start button for a second you may get spark and that's why you can get a pop out of the exhaust.
Also if you have a bad battery and others here are advising you to push start keep in mind the alternator was only designed to handle so much load. Bad battery and running the bike like that could cause problems with your charging circuit. Make sure you test the battery and make sure it's not bad before attempting push starting.

Check out chacal's battery section and there is an explanation of battery voltages and what they mean as far as battery condition. The second thing you can do is to remove the battery and have it load tested to check if it's good or not.

MN

 

Ok guys, I charged the battery (I'll test the voltage some other time to make sure it's a good battery) - Tried starting it this morning with a full charge and it started right up on the first try.

Now i have two problems, which i need to figure out, not sure if i can get some help. I let it stay on for about two minutes to warm up and then shut it off because of two problems.

1. The exhaust was blowing TONS of smoke. Not sure why. I had carb cleaner sprayed through each jet of the carbs when i had them off, and i have new oil, so maybe one of those two?

2. I was adjusting the choke to stay at about 2000 RPM. It instantly shot up to 4000 with a full choke so i reduced. Eventually, I had the choke off and the bike was still revved up at around 2500 RPM (NO choke) and was still sounding like it was warming up.... without the choke??

Is this an issue? That's never happened before, I assume when you shut off the enrichment cycle, the bike would start to die out and the RPM should lower???

I'm thinking if it's stuck on 2500 RPM without choke, i need to tweak the idle screw so that the valves are a bit more closed, because it's acting as if the valves are open (Like when you pull on the throttle and it revs up) ?? Possibly that?

 

1. Smoke could be an issue what color was it and have you done a compression test on your bike?

2. first things to check are look and see if the throttle linkage is hung up somewhere as this is a common issue on fresh installed carbs. Also try to turn the idle screw out and see if it is just holding the butterflies open too much. you need to get the idle down to the 1000 rpm range.

 

I checked everything and it is all ok. Smoke was due to not running for a while i think and because it was HIGH RPM, fresh new oil, and probably carb cleaner burning through the carbs. Hadn't run the thing in months and the last thing inside the carbs was carb cleaner.

Smoke stopped, got the RPM lower by turning the idle screw a bit, i overcompensated, i believe.

Everything seems to be running great, i'll let you guys know if anything else goes wrong, haha.

And yes i did the compression text and everything was A-ok.

 

reason I asked smoke color is blue is oil, black or grey is likely from carb cleaner etc ime. I ask about the compression test for 2 reasons. 1 to make sure you didn't have oil bypassing the rings and burning, 2 to see if you had done a wet test and had oil in the cylinders.

generally it is the idle screw but a number of people recently have had their throttle linkage hung up so its a good thing to check.

glad it is running good now have fun with it.

 

Yeah, it was black/grey burning through and out of the exhaust, most likely carb cleaner.

Yeah, i checked the choke to make sure that wasn't caught, and i checked the throttle cable, all was fine. I just need to finish fixing the front brakes (I believe i damaged my caliper trying to put on brake pads that were sent to me for the WRONG bike, which is another story... haha)

Once the front brakes are good i'll be riding the sucker.

 

Check the REAR brake before any riding. READ: http://xjbikes.com/Forums/viewtopic/t=15874.html