[formz]

Right side is backfiring occasionally on deceleration, leading me to believe that that side is probably running a little rich. As I understand it, the air/fuel screws on each carb should be equal. But what if one side is running rich?!

 

[Shep]

The idle mixture screws do not have be equal physically,they should be set per cylinder to allow for anomalies in the sides.



Is it,"Backfiring" or,"Popping" as the two are symptoms of a different fault.



Backfiring is usually,but not only,a fault with the exhaust system/leak and is unburned fuel being ignited in the exhaust.



Popping is usually a fault with the Air-Cut-off mechanism/s or possibly Carb Float heights causing a lean condition on deceleration.

 

[formz]

It's backfiring. Although not always. I JUST had new a new exhaust put on there too.... but I doubt there is a leak. Thats why I assumed it was running rich on that side and fuel was escaping unburnt.

 

[Shep]

That does point towards the carbs or ignition.Also checkout the troubleshooting section in the manual as they sometimes give clues.



Try swapping components like plugs and plug caps to see if the problem swaps sides?

 

[formz]

Will do, thanks.

 

[bandit]

Will do, thanks.

take,and post a picture of your plugs.

 

[formz]

Alright guys here we go:



Lighter colored plug is the side that is backfiring and the spark plug was a lot hotter than the other. This is also the side that is backfiring. It pops quite a bit at idle and then will produce small backfires while coming off throttle, but lessens in frequency when it warms up. Here's where it gets weird... the actual EXHAUST temperature is HOTTER coming off the left side that doesn't pop which is also the blacker plug. These all seem like opposites to me!

 

[versicolor]

to me those look extremely lean.

 

[formz]

Really? It looks like one is lean to me, but I will always take other's opinions.



Carbs are both rebuilt by me, new air filter, new inline fuel filter, new plugs, etc... not sure what would be causing such a lean condition.

 

[versicolor]

Well from the pics it doesn't look like either one has that nice brown coloration. They both look more on the whitish side. Maybe it's the way the pics came out though. How many turns out are the needles set at?

 

[formz]

They are both at factory 2.5 turns out. I think tomorrow I'm going to set them according to thr manual procedure. I have read it, but it only seems to talk about one side. Is there a side I should start with?

 

[black81silverwing]

I had an occasional backfire on deceleration also. Following some reading tonight I inspected my plugs. Realized the gap was off. 0.024 versus 0.028. Adjusted and runs much better without backfiring. Like several times before, I tweaked and found more power. Wahoo! Now you guys have me wanting to tweak the carb a little more. My plugs look similar to the lighter one above. Perhaps a little lean? Plan on doing so in the morning.



Thanks again for all the information. Very much appreciated.

 

[Shep]

Have you checked the Air-cut-off Assembly on that side?

 

[formz]

Shep I haven't checked it. I did replace it though when I rebuilt the carbs. Would I just be looking for holes?

 

[Shep]

If you replaced it with a new one I doubt it would have holes in it.If it did that would have been real bad luck

I'd still check for exhaust leaks and carb boot leaks.They can be really really sneaky.I had an old set of stock cans on and there was a hole hidden inside the sliding bolt thingy(Technical term<grin>) that secures the exhaust to the bracket.It didn't show or sound much until I revved the bike and of course really only showed when it got big-enough but was causing backfires before it made itself known

 

[formz]

I guess that is thr next step. I have brand spanking new carb boots on there, but im still using the original clamps so maybe they aren't sealing.

 

[Shep]

I had to make some custom clamps on one of my CXs,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=19&t=76&p=367&hilit=jubilee#p367





http://www.diytools.co.uk/diy/Main/sp-75-2338-28316-draper-8mm-wide-hose-clamp-set.asp



At the time I couldn't find any OEM ones and even the prices I did see which were out-of-stock were pricey for what they were.



They are 8mm wide so thin which is around 3/8" wide.

 

[formz]

I have those and could not freaking get them to work! They refuses to clamp and get tighter. It wouldn't screw. Dammit.

 

[Eurovee]

I JUST had new a new exhaust put on there too..

What exhaust has just been fitted?

Some aftermarket exhausts are more `freeflowing` than OEM and may require tweaking of the carb jets to compensate for this.

Your plugs look a smidgeon lean, a result perhaps of the new pipe, which could be a source or contributory factor of the `backfiring`.

 

[formz]

No crossover, the harley mufflers do have the baffles. I'm thinking some carb tweaking is in order.