No start problem

The other night I was on my way back to college on my 83 xj650 and the engine surges down with instant power loss so I rolled on to the shoulder of the freeway and called a friend to come pick me and the bike up because It wouldn't start at all. The next morning me and my friend went over almost the entire bike, going through the fuel system maybe thinking I got bad gas and something was clogged, not that. Checked the electrical system and it is starting fine. When I try to start it you are able to hear the transmission turning but the engine doesn't catch so we kept trying and the enging finaly caught for a moment, it sounded like rocks were popping around inside the engine, I dont have the necessary tools up here to take the engine apart so I'm gunna have to take it home but has anyone else experienced this problem and what have y'all found to be the issue?

 

For starters check these:

Sounds like a possible lack of fuel. Put some clear tube on the nipple at the bottom of your carb float bowls, unscrew the drain plug and see if gas comes out.

Might be an electrical problem. Check if you have spark by taking out a spark plug and hold it next to a bolt on the engine. With the lights down crank the engine and look a for spark. Do this on all 4.

Let us know the results, this will point you/us in the right direction.

 

how about the timing chain? might have slipped a tooth or two on the sprocket.
that might expain the noise.

 

A compression check will, in one quick pass, verify whether you have any problems with valves, timing chain, etc.

If the plugs aren't wet, you can try starter fluid to see if she runs for a few seconds from that. If she does, then you know you have a fuel problem. If not, and the compression's OK, then ignition would be the only thing left.

 

With the symptoms you describe, how do you know that the tranny is turning? That right there is bad. The starter should only turn the crank. Pull in the clutch when starting or place the transmission into neutral.
Remove the left hand (as you sit on it) crank cover and observe the timing plate as you activate the starter. Does it turn? If not, you have found your problem. That "rocks in the the engine" sound could be the starter chain going south or, if the engine turns over every time, the starter clutch sprag assembly could be dying. Either one would necessitate splitting the case and replacing the assemblies. One of our members found his starter clutch housing cracked into pieces so I'm leaning this direction. I'm with SQL, do a compression check and follow his lead.

 

I'm getting spark on all 4, theres fuel in the carbs so i dont think its a fuel problem,

another person that i feel is very knowledgeable about engines also said it could be the timing chain

the reason i know the tranny is turning is if i leave the bike in 1st and pull depress the clutch the back tire will spin a little, its always done this since i got the bike and the clutch is adjusted all the way out so i cant go anymore so i left it.

I cant do a compression check up here, I think we have the stuff to do that back home

I was going to try the starter fluid but the "rocks popping" was very discomforting so i stopped turning the engine altogether after I heard that.


When I get back home I'll let y'all know what I find and thank you all for your help, it's greatly appreciated.

 

The rear tire creeping while in gear with the clutch pulled in is normal. I haven't seen an XJ that doesn't. Mind you, this is with the bike up on the center stand. On the ground, you shouldn't be fighting with it. If it creeps on the ground, you have a problem and need to adjust the clutch system.

 

Your right, it does it on the center stand not on the ground, now I know that is normal, thank you.

 

why it quit ...?
if the timing chain goes the valves stop but the pistons don't, you'd know if that happened
the rocks in a can noise sure points to the starter clutch, did you change the oil lately ?

 

Would the starter clutch make the engine stop in mid ride? I dId an oil change 800 miles ago so it wasn't all that recent.

 

"Would the starter clutch make the engine stop in mid ride?" i don't think so
did you look at the vacuum line to the fuel valve ? that would be just like running out of gas
is the tank clean ? could the in tank filter have collected gunk while running then released it when it stopped
how do the plugs look?
did the motor just quit or just loose power?

 

Are you sure your battery simply isn't bad? Did you do a load test on it?

I have also heard the tumbling rocks sound you heard. My bike has done it in the past after sitting for a long time, and I think it has something to do with the starter remaining engaged. At least partially. I was going to start troubleshooting mine but the sound went away after a fresh battery and a few starts of the bike.

 

The battery is just fine

I popped off the valve cover and the sprocket on the intake cam is completely gone, there's not even a sign that it was there so when i got home for thanksgiving im expecting to find the pieces of the sprocket inside the engine.

I hope nothing is too messed up,

would the valves hit the pistons in the case the valves aren't moving?

if so I may have serious problems