Engine breaking down, flames and popping through exhaust

[Bill Pine]

If popping in the exhaust and flames you have a possibility of a few different things going on.

As already mentioned, proper firing order is important. The two coils fire two spark plugs at a time. One cylinder is on compression stroke and the other is on the exhaust stroke. The one coil fire cylinders 1 & 4, the other fires 2 & 3.

But, lets start with flames. In order to have flames out of the exhaust there has to be a significant amount of un-burned fuel in the exhaust system.

Is this caused by a carb flooding over and too much fuel to burn.



Secondly, in order for the fuel to ignite, it needs an ignition source. The only ignition source will be the spark plug on the ignition cycle. Since the exhaust valve is open when the spark plug ignites on the wasted spark cycle, that is allowing the fuel in the exhaust system to be
If the firing order is correct, it is time for a compression test, valve clearance check & adjustment and then a compression check following.

From, there you also need to look at the carbies for flooding.

One more thing, if for some reason the camshaft timing is off, you can have these types of problems.

Randy - RPM

Wow, if I Wasn't in the shit before I sure am now. I will take all in And be very busy for a couple days (years) so again Wow and thank you.

[Bill Pine]

I think the connection of the wires to the new coils and or wires to the new spark plug caps may be the problem.  If you reversed the spark plug wires completely - #2 to #1, #1 to #2, #3 to #4, and #4 to #3, the motor won't start. But it will eventually backfire so loud it will make you duck for cover.  INCOMING!!!   

That one I had on my Kawasaki GPz 550 unitrak. I almost got deaf.

[Bill Pine]

Just an update on the engine running.
I removed the muffler and ran the bike, it was loud but a whole lot smoother.

I bought the bike with a 4 into exhaust system and I don't think the tuning was done.
I will either put on a standard system or get the bike tuned. 

Thank you to all who have tried to help me. 
I have been impressed and grateful of all the help.
Thank you,
Bill.

[red]

Just an update on the engine running.  I removed the muffler and ran the bike, it was loud but a whole lot smoother.  I bought the bike with a 4 into exhaust system and I don't think the tuning was done.  I will either put on a standard system or get the bike tuned.  
Thank you to all who have tried to help me.  I have been impressed and grateful of all the help. Thank you,
Bill.

Bill,

I have V&H 4-2-1 headers on my FJ.  I do not believe "tuning" could cause or cure the problem that you report.  I believe that the muffler was just allowing unburned fuel to collect inside the pipes, until there was enough to detonate.  Removing the muffler did not fix the problem, but now there was no place to collect the unburned fuel, so, no detonations.  I believe the standard exhaust system would have exactly the same problem, but maybe quieter.

When you start the bike from dead cold, all four pipes should get hot at the same rate.  You will need to work fast, but start the bike from cold, and touch each pipe in order, repeatedly.  Keep that finger moving, from one pipe to the next.  As they get hot, SKIP any pipe that gets too hot too touch, and only touch the others.  Sight unseen, I would bet that one pipe will stay cooler much longer than the others.  That would be the cylinder with a problem.  It may have a bad plug, or bad cap, or a bad high-voltage wire.  You may have one carb with a bad needle-and-seat, or a bad carb float (or a bad float setting).  Beyond all that stuff, the next thing might be to do a compression check.  I believe that "tuning" right now would be a waste of money.

[FJ_Hooligan]

A spray bottle with water will help you save your fingerprints.

[Bill Pine]

A spray bottle with water will help you save your fingerprints.

I have had the filters off and ran the bike and found some spitting from carby #4 I am going to run it again without the filter box attached briefly but there was some spitting from the back of the carb.
I bought the bike second hand and it had been messed with and as per the previous owner's comment "I tuned the carbies on the bench" so they're fine.