I go around 40 miles on my 89 fxr and it starts backfiring and dies. Wait 10-20 seconds and it fires right back and will go another 10 miles or so and does the same thing. But if I let it set for 30 minutes or so it will go the 40 miles again. Bad ignition or what??? My trouble shooting abilities aren't very good.

 

If it was me I'd be thinking gas filter, but brake it down its one of three things,
Fuel, Electric or Timing. Since the bike is running when it dies that kinda sorta
rules out timing. Next time you go out take a spark plug with you, and as soon as it dies shove the spark plug in a spark plug wire and see if you get spark, if you got spark then its got to be fuel. Does your bike have a filter on top of your fuel valve.
if it does is it as dirty enough to restrict the flow of fuel is there a lot of trash in your gas tank that is getting sucked up on your filter or fuel valve? These are just thoughts to ponder.

 

Bikes old enough I'll agree with 6 gun about the petcock screen probably plugging up on you . Components on the electrical side usually either work or don't , rarely you'll get an intermittent thing like you describe .

Pull the fuel line at the carb and blow back through into the gas tank on both on and in the reserve positions on the petcock and see if that helps , if it does make plans to drain the tank completely and either clean the screen or replace the petcock itself .

It doesn't may be time to hit a local shop to look at your ignition module or coil .

 

Start with the easy stuff first. As 6 gun mentioned, look at the external fuel filter if it has one. If your petcock has a filter in the tank, there might be enough crap in the tank to block the filter after a bit. Has the stock ign. module been replaced with an aftermarket one? If so, is it in the nosecone behind the "points" cover? If so, 40 minutes sounds about right to get it heated up enough to fail.

 

Check the ignition module...Borrow one from someone and try it.
The reason I say this is because it appears to me that the ignition module is working fine until it gets hot and then something is freakin' out in there.
I have encountered this problem quite a few times on older bikes with electronic ignition.
They will do exactly what your bike is doing....It can be a real pain in the *** to track an intermittent ignition problem like that.
Also look at the wire that runs from the sensor in the cam cover to the ignition module as they are prone to failure with age, as are the sensors themselves.

The key is the heat...The longer you let it cool, the longer it takes to get hot enough to fail again.

 

Coil could be going out. When they get hot it'll start an intermittenting problem.

Also check the plug wires. On a FXR the wires have been famous for the brass cracking at the 90* bend coming out of the coil. I chased my tail on a similar issue , and found a broke plug wire.

I have also had the wires work them selves loose ie coming out of the coil. I now put a marine sealant around the rubber boots at the coil to prevent this and moisture.

 

Tank does look a little flaky on the inside. I have an inline filter on it. Should that filter be full, half full or what? Most of the time when it dies it looks less than half full but It doesn't look full when its running either