Well I have a problem; I took off on a ride after it warmed up and rode to the bank, about 2 miles away. I parked it for less than 2 minutes, got back on, pushed the start button and a really LOUD pop /backfire came from my carb. (Then died) Not a normal sporty cough. The rubber intake seal popped off and my carb was kind of just hanging there. I took off the air cleaner and tried pushing it back on so I get home. I thought it was on ok enough so I started to try to turn over the engine and it just turned and turned not starting, then my battery just died. (I usually keep it on battery tender if I think it's running low, and I hadn't for about a week.) So I had to tow it home. I put the battery tender on overnight.

The next morning, I pulled off the air cleaner and looked closer and I noticed a vacuum hose came off and was torn/frayed. (the 90 degree thing.) I took off the rubber carb seal and it was ripped in 2 places. So I thought, just replace this and it should start up. Wrong! It just kept turning but wouldn't start. SHORTLY after that, my battery died again. So here I am.... could this be my crank sensor??

UPDATE!!
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It wasn't the crank sensor. It was the seal #27002-89 for the intake. Not having a good seal did not allow it fire up. As soon as I put on a new one, and made sure it was on properly, the bike started right up! Now I need to get a bracket to hold the carb on.

 

It actually blew the carb off the bike with the air cleaner on!!!!! Damn. That is a hell of a backfire. Are you running nitrous? I would have to say you have major issues with something. Take some pics maybe that would help. I have never seen a carb come off when the A/C was on. Maybe you have a valve stuck open.

 

No, not off the bike off the intake. A valve huh? How about a CKS?

 

The A/C holds the carb on. I know it didn't come completely off. Unless your A/C is really weird then that is way abnormal. I can't even imagine how the hell that happened. Now if you try to tune without the backing plate on the carb can pop off but that isn't hard to do. What happened to your bike was mechanical, or at least that makes sense because of the damage done. I would doubt that it is a crank sensor. Usually that causes poor running, a "limping bike" things like that. And yes it will cause it not to start. Your bike won't start because you had a massive backfire. Usually those are caused by bad internals. Something went wrong and loaded up with fuel and BANG, a bigass backfire. Now I have a whole bunch of experience with stuck, broken, well pretty much anything that can go wrong with the deep internals of an engine. I am on the crew of an outlaw pro mode dragster and I have seen a lot. Now that is on a HIGHLY modified engine and it is a car, but still an engine is an engine. By the way even in that environment I have never seen a carb go flying without NOS being involved. To me it seems like something went wrong, and is still wrong inside your engine. If you have a stuck intake valve it won't start. Or if it does it will just backfire again. You really need to turn the engine over and listen, just see how it feels. This is not hard to do. Just get the bike tire off the ground. Of course I may be reading way more into the intensity of the backfire. I wasn't there and I don't know you A/C set up. But if it did that much damage that would indicate, to me at least that you have something very wrong inside that engine.

 

But timing can also cause a backfire, a lean mixture can cause a pop but rarely do these cause damage. They are just annoying. The main reason I suspect a valve problem is the damage and the fact that it now will not start. But of course I am diagnosing this over the Internet so what do I know.

 

I had a backfire once that blew the vacuum hose off the petcock, too. Replaced the hose and started back up. Not sure what caused the backfire, but never had it happen again. Lost vacuum will cause a no start condition as vacuum is required for your carb to pull fuel.

 

Wish you knew what caused it.

 

Well there's a number of possibilities here, and also depending if the back fire itself is what actually blew the seals out, or if the seal was acually fallling apart on it's own first and caused the major backfire. Keep an open mind now, sometimes it can be the littlest damn thing that may be the root of your probem. Start off with the basics, I'd personnally reset the entire manifold mounting, including reseating the seals from the manifold-to-engine with it, not just the carb-manifold gasket. Then closely check over your vacuum lines, pull your petcock vacuum line and test it dirrecty to make sure it does open up and pass fuel under vacuum. Check your plugs and make sure they have spark. From there, there's a number of directions you could work toward depending if you found any results from what you did already. But before getting any deeper into the motor, make sure you get yourself a manual to help guide you through anything further.

 

And don't eliminate the battery as problem just yet, because you think you charged it back up. Check your battery voltage, and take it to an autoparts store and have it load tested. It is possible to have a bad battery that can seemingly crank just fine, but the voltage drop is too much to sustain ignition function. Not sure what the harley cutoff point is, but many aftermarket ignitions require 6-8 volts to run, so if voltage drops below that during cranking, the bike just won't start.

 

harleys dont like them short run still cold!
try some starting fluild
then compression checks in order