ok yet another problem

i ran into a real nasty backfire, it is on my 1982 xj 750 seca engine it turns over and tries to start but it kick a loud pistol backfire out of exhaust, it has compression sitting at 150,139,140,150, im in the process of getting the tool for the shims to adjust the valves, my carbs do need a cleaning, but could anything else cause this nasty backfire, i dont believe it could only be the carbs doing this could i have a vaccum leak on my head or exhaust that would cause this or low oil?

 

It it possible the coils or pick ups are reversed? How is your battery voltage when cranking the engine over?

 

OHH I NEVER CHECKED I DID JUST PUT NEW PICK UPS AND MY COILS I PUT IN THE BEST TO MEMORY I FORGOT TO LABEL THEM IS THE CYLINDERS FROM FAR RIGHT OF BIKE 1423

 

#1 is at your left knee, you call the cylinders 1,2,3,4.
The firing order is 1,3,4,2
The coil with the longer leads goes to 1,4, the other coil is 2,3 (someone mention the wire color) they are usually labeled.

 

OH WOW YEA MINE IS OUT OF ORDER BAD THEN I WILL CHECK THEM AN RE SET THEM AND SEE WHAT HAPPENS

THANKS THIS IS A BIG HELP!

I ALSO HAVE ANOTHER ENGINE THAT NEEDS PARTS IM USING IT FOR MY LEARNING AND EXP. ONE

 

Please, for the sake of my eyes and mental thoughts screaming at my brain, can you take off the caps lock?

Thank you.

 

yea sorry about that im at work and the system we use caps only so i forget to turn them off.

 

WHAT IS THE GAP IN A SPARK PLUG SUPPOSE TO BE AT?

 

0.028-0.032

 

http://xjbikes.com/Forums/viewtopic/t=34431.html

 

Let's step back and address the original title of this thread:

"ok, yet another problem."

THESE AREN'T "PROBLEMS." The things you're encountering are simply symptoms of the items you haven't attended to yet or thought you could overlook.

Here's the deal: if you plan to ride and use this motorcycle without constantly "fighting" with it, you need to completely and thoroughly "recommission" it. Every maintenance or "wear item" needs to be attended to before it's going to work for you.

The best way to do this is to go through the "maintenance" section in the service manual, and perform each and every procedure, in order, leave nothing out. As you do this, you will find parts that are worn, rusted or corroded, dried out and crumbling, or are otherwise unfit for service. Replace these parts; clean, inspect and refurbish those that are still serviceable. Perform each and every service procedure and adjustment.

Anything you miss or think you can ignore will come back as a "problem." Do it right, and you will have very few "problems." How many and how often is up to you.

Read this: http://xjbikes.com/Forums/viewtopic/t=24010.html You need to take charge of your process. Right now the bike is in charge.