Engine breaking down, flames and popping through exhaust

[Bill Pine]

Hi there, I have a pronblem with the engine running rough on my FJ1200, 1995.

I have put two new coils and fitted 4 new spark plug caps.
The bike starts but runs rough.
There is a lot of popping through the exhaust and it can also spit some flames.
It ran great for a short time and then started running rough again after the install of coils and plug caps.
Looking for ideas and any help/suggestions.
Thank you.
Bill.

[balky1]

One or more of the intake manifolds and/or their O-rings is probably cracked leading to lean condition and popping.

[Bill Pine]

One or more of the intake manifolds and/or their O-rings is probably cracked leading to lean condition and popping.

Thank you, I need somewhere to start and all help is greatfuly appreciated.
Bill.

[balky1]

Did you try to feel the exhaust pipes after starting? If one or more are cold those cylinders are not firing. In that case, since you fiddled with electrics, start from there.

[FJ_Hooligan]

Verify the spark plug wires are routed to the proper cylinders.

[TexasDave]

Verify the spark plug wires are routed to the proper cylinders.

BEST advise yet. Don't know why I didn't think of it. I have done the same thing on a VW with the same results.

[oldktmdude]

Don't know why I didn't think of it. I have done the same thing on a VW with the same results.

Would it make a difference on a VW?

[Pat Conlon]

...out of the blue.....love this place....

[ribbert]

Don't know why I didn't think of it. I have done the same thing on a VW with the same results.

Would it make a difference on a VW?

Not that you'd notice.  

[Bill Pine]

Verify the spark plug wires are routed to the proper cylinders.

I like your answer but sadly yes they are correct. 

[Bill Pine]

Did you try to feel the exhaust pipes after starting? If one or more are cold those cylinders are not firing. In that case, since you fiddled with electrics, start from there.

No that I did not do BT will be playing on the weekend.

It very interesting all the possibilities. Thanx.

[Bill Pine]

...out of the blue.....love this place....

So impressed of all the response and knowledge that is out there. Really glad I made the effort to ask for help.

Thanx again. 

[fjbiker84]

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!!!   

[balky1]

 

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.

[racerrad8]

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 ignited.

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