2008 sportster 1200 backfire/stumbles

[stray dog]

...With the combination of high flow air filter and nasty loud exhaust which has little if any back pressure you may have already found the culprit...

+1
What exhaust do you have? Loud & Nasty is different to everybody

If anything like straight pipes you don't have the back pressure to keep fuel mix in while valves are in overlap and you will be loosing power in low and mid range. Not to mention difficult to tune.

 

[dbmg]

I will check that out in the morning. I have had the seat off once and don't remember anything but the MAP sitting under there. But, I will check that out. No trouble codes, I've checked that a couple of times. Could it be that I am not keeping my RPM's up at low speeds? I have been staying in second gear more now in town to make sure I am not bogging it down. This is my first motorcycle in almost 50 years. I rode much smaller Honda's back then so maybe I am just working on a learning process all over again.

As they say with a Harley you need to keep it up on the cam. A slant to a Harley but its all in fun. Remember you are riding a piece of farm machinery and not a smooth running Timex watch like the Metrics. That's what give the Harley the character that most desire but can not appreciate till one owns a Harley...:s

 

[T in Texas]

Just took about a 35 mile run on it and if I am not mistaken, it seems to be doing better. It could be possible that since it has not spent much time on the road lately, the seafoam is doing it's thing. I had one miss at about 50 miles an hour then it seemed to run fine. In town I kept the revs up a bit and it seemed to sound a lot better. Maybe I just need to run it around these country roads a bit more. I will pull the seat in the morning and check for a fueler box.

I don't know what brand of mufflers are on it. It has the long and short Sportster type exhaust with a "baloney" cut off to the sides. It is one loud sportster and The neighbors don't mind. They like Harleys too.

 

[stray dog]

Just took about a 35 mile run on it and if I am not mistaken, it seems to be doing better. It could be possible that since it has not spent much time on the road lately, the seafoam is doing it's thing. I had one miss at about 50 miles an hour then it seemed to run fine. In town I kept the revs up a bit and it seemed to sound a lot better. Maybe I just need to run it around these country roads a bit more. I will pull the seat in the morning and check for a fueler box.

I don't know what brand of mufflers are on it. It has the long and short Sportster type exhaust with a "baloney" cut off to the sides. It is one loud sportster and The neighbors don't mind. They like Harleys too.

Hopefully just a little gum/varnish in fuel system. Gotta love the seafoam.

Good luck!

 

[T in Texas]

This is what seemed to happen in my case. I bought the bike used from a dealer, it came with the exhaust and screaming eagle stage one intake. After reading a bunch of posts on this site I went with a fueler. I chose the Cobra FI2000R and all the problems are now a thing of the past. It was way to lean. So far I have not made any changes to the factory settings. It now growls to life and goes down the road with no missing and no backfire. I guess what happened is when the last owner traded it in, he took his fueler off. That was all it needed all along. I had put on a new air filter, plugs, IAC, plug wires, and a new battery, it took the fueler to get it right. Well anyway, with all the things I added it should be good for some Summer time riding.

 

[stray dog]

This is what seemed to happen in my case. I bought the bike used from a dealer, it came with the exhaust and screaming eagle stage one intake. After reading a bunch of posts on this site I went with a fueler. I chose the Cobra FI2000R and all the problems are now a thing of the past. It was way to lean. So far I have not made any changes to the factory settings. It now growls to life and goes down the road with no missing and no backfire. I guess what happened is when the last owner traded it in, he took his fueler off. That was all it needed all along. I had put on a new air filter, plugs, IAC, plug wires, and a new battery, it took the fueler to get it right. Well anyway, with all the things I added it should be good for some Summer time riding.

Glad you got her running good!

You said you had a stage 1 intake and that you replaced the AC. What kind of AC is on it?
If you have a K&N, you don't replace those, you get the recharge kit with cleaner & new oil.

 

[T in Texas]

Yes, I got a new K&N filter, I don't know what the last owner cleaned the old one with. It must have been carb cleaner cause the mesh was starting to decay.

 

[stray dog]

Yes, I got a new K&N filter, I don't know what the last owner cleaned the old one with. It must have been carb cleaner cause the mesh was starting to decay.

10-4

Caught a friend once throwing one away and replacing it with a standard on his new-to-him truck. :bigsmiley21:

 

[T in Texas]

Thanx Stray dog for your posts, I'm looking into that recharge kit right away!