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Discussion Starter · #1 ·
I have an 03 sportster 1200 that is all stock it runs great under load but when just cruising in any gear it's fine untill I touch the throttle jut a little as soon as I start to accelerate it misses. If I start off heavy with the throttle it will rip through the gears no problem. It only a partial throttle. I tried new plugs fun better but did nothing for the problem l also have an air filter on order as mine is soaked with oil bike has 10,250 mi I bought it used last year and it's been like that since I bought it
 

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I have an 03 sportster 1200 that is all stock it runs great under load but when just cruising in any gear it's fine untill I touch the throttle jut a little as soon as I start to accelerate it misses. If I start off heavy with the throttle it will rip through the gears no problem. It only a partial throttle. I tried new plugs fun better but did nothing for the problem l also have an air filter on order as mine is soaked with oil bike has 10,250 mi I bought it used last year and it's been like that since I bought it
The air filter is washable . :thumb
 

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The MoCo Service Manual and the Parts Book should be ones first purchase after the bike . :nod
 

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Discussion Starter · #6 ·
Wow thanks ! I guess I'll have to get one. I've been wanting too but i had to get a helmet, a riding jacket with armor and a couple pair of riding gloves.
 

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I {Heart} Hookers.
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I have an 03 sportster 1200 that is all stock it runs great under load but when just cruising in any gear it's fine untill I touch the throttle jut a little as soon as I start to accelerate it misses. If I start off heavy with the throttle it will rip through the gears no problem. It only a partial throttle. I tried new plugs fun better but did nothing for the problem l also have an air filter on order as mine is soaked with oil bike has 10,250 mi I bought it used last year and it's been like that since I bought it
It's not your air filter. It's your primary jetting. Either your primary jet is too small, or the carb air/fuel screw needs to be turned out a touch more to add a bit more fuel. You're experiencing a lean condition in the primary to midrange transfer.

The other issue it can be is the beginning of the decline of your accelerator pump diaphragm, as they deteriorate in about 10 years, and the rubber starts to peal off the surface, leaking fuel and reducing effectiveness on accel.

I'm betting on it's your jetting and or AF mixture.

A clogged or oil soaked air filter element will make the engine run richer. You can clog over 2/3rds of that filter, and the engine will run fine.
 

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Or leaking intake seals in combination with the previous suggestions.
 

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nope....change your gas......I run 87 octane in my 07 nightster...115,000 miles on it...if I put 91 in it......... it runs like a dog
:jaw wow, and I thought I had a lot at 28k miles.
 

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I {Heart} Hookers.
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You mean......your 2007, EFI Sportster?

Yeah.....
 
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28,000...you must only ride on Sunday's LOL I have more than that on my 2010 48sportster
Actually it had 28k on it when I bought it in July. I don't get to ride a lot because of school. I did put 20k in one year on my vrod before I crashed it in 2010. I'd say 1000 miles were on the 1/4 mile on the vrod. A third of that was with the front tire in the air.
 

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Discussion Starter · #18 ·
Started to take the carb off and noticed that there was a vacuum line on the back of the carburetor that had a Y shaped vacuum line splitter, one of the lines that went a black piece behind the fuel shut off was almost broken in half and was dry rotted, so I figured I'll replace that before removing the carburetor . Hopefully that will fix it. If it does I would still like to remove the carburetor in the future just to replace some of the common things that go bad on a carburetor that is almost 13 years old that were mentioned in the replies to my post. I'll let everyone know how it goes. And I would to thank everyone for their input it's really appreciated! . I added a pic of the line but not sure if it will work I'm new to the site and still trying to figure it out, I'd like to have a pic of the bike near my ID instead of the yellow star lol
 

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Discussion Starter · #20 ·
Well it was the vacuum line ! This is the best it's ever ran nicce smooth acceleration in all gears. I bought the bike last year at the end of October put 3300 mi on it from Oct till early May then had foot surgery and last week was the first time back on the bike .looks like it's going to be another cold winter on the bike for me lol. As long as it's not snowing or iced up on the road I ride the bike. So far I've been on it at around 17 degrees not counting the wind chill but I love it! I wonder what its like riding in the summer time hopefully I'll find out next year!
 
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