Hey friends - I have a '97 Heritage. It has started backfiring a bit as it is running especially when cold about every 10 seconds...I'm in FL so it's not really cold. Going down the highway is fine but backfires a lot when backing off throttle. I checked fuel filter = it's fine, plugs look fine maybe a bit lean.

Any ideas?
thx

 

What size jets? After market A/c or Exhaust? Try backing out your mixture screw on your carb a turn or two.

 

Thanks I'll give that a try. Yes aftermarket exhaust. This just started though.

 

let me know if that works.

 

Something is making your bike run leaner... my guess would be clogged jets or a vacuum leak. At least, that's where I would look first. Vacuum leak is easiest to test... spray water around hoses, intake manifold, and carb. If the idle rises, you have a leak.

Try seafoam in your gas... half a can per tank for the next few tanks.

 

The bike isn't running lean. It's backfiring because the air coming in through the back of the exhaust is burning the un-burnt fuel up near the header pipes. You may need to reduce the enrichment a tad. It's a compromise....a bit of backfiring on deceleration, or a slightly lean running engine where all of the fuel is burnt before the exhaust. A slightly smaller diameter baffle will also help.

 

The vacuum line is connected to the carb but loose on the other end when I took it off. Where does this connect to?

 

Took the carb off to drill out the mixture screw plug. Turned out 3/4 turn, reinstalled and it works perfectly. Not a pop, caugh or anything. Thanks bbeavers76!

It's funny I was looking at your Converse shoes and that is what I was wearing Friday....and I'm 65! = refuse to grow up!

 

That screw didn't move until you adjusted it and if, as you say, there were no changes (including you didn't move to a lower elevation) you are simply covering up the real cause. It may show up later again. If the vacuum hose was 'loose' that would be a good place to start.

C#

 

I've been messin with baffles etc and I think this may be the change that created the unbalance...??

On the way to work this AM I noticed that there was gas coming out of the overflow hose on the bottom of carb. Could it be I dislodged a bit of grid that is interfering with the float needle?