Another "running lean" question

Although I am not positive yet, I beleive my engine is running a bit lean as I get a popping noice coming through the exhause when I'm slowing down or going down a hill.

I saw on another thread that a rider started using a higher grade of gas, and the popping went away for him. I'm using 87 octane (no ethanol) gas. If it is true that my machine is running lean, does that mean it will be running lean when using a higher grade gas? I'm might try some 92 octane (ethanol-free) gas and see what happens to the popping sound. But if I understand correctly, a higher octane gas needs more heat to ignite and thus burns hotter. If my engine is already running lean, and I use a fuel that may cause my engine even hotter, I'm afraid I may actually do some damage. Then again, my understanding of octane grades may not be correct.

 

"Lean" is the term used to define an insufficient ~~> amount <~~ of Fuel.

The grade of Fuel won't change a Lean situation.

First:
See if you are running Lean by removing your Spark Plugs and inspecting them.
If your bike's running Lean those Plugs will clean and with the Ceramic portion of the electrode very close to still looking new.

We can fix that.

But, popping also happens when Exhaust Flange Donuts are burned-up or blown.

Check the Plugs and get back to us.

We'll make a "Tweaker" out of you.

 

Have a look here for how to read your sparkplugs:

Reading spark plugs

Backfire under de acceleration normal cause lean backfire. Mixture too lean or pilot jet too small. Pod filters? 4 into 1 exhaust?

General backfire guide:

When does the Popping happen?

If you are slowing down and therefore backing off on the throttle does it pop then?

The popping is most likely a lean backfire.

If you get popping on acceleration check the exaust gaskets for leaks.

Popping on idle, bogging down, poor running (and hesitation or surging at even throttle) check plugs and coils. Breaking down under load.

To do a "plug chop" test:

Run the bike at the rev range you want to test, using care pull the clutch and kill the engine. Glide to a stop. Take the plugs out and have a look at what they look like compared to the link I gave above.

Remember on a bike you run the risk of loosing control when the motor is not running.

What the wrong Octane rating gives you is not a backfire, it is a Rattle under load, i.e., going up a hill wide open throttle.

The higher the octane the Slower it burns. The XJs are suppost to run Regular grade of gasoline. If the grade of gasoline is too high it will foul your sparkplugs and carbon up your piston tops and combustion chambers.

 

Ethanol is an oxygenated fuel, meaning you could end up running leaner on an ethanol mix then on regular gas.

Not a problem when you have a fuel injection system. Can be a problem for our bikes as we don't have an 02 sensor to compensate.

-Steve

 

Is there any guidelines as to how long you need to run in each rev range? For instance, will a few seconds, say 10, in the rev range give you correct readings from the plugs? Does it matter what gear you are in? To hit redline in 1st or 2nd is okay but a little harder to do in 5th.