I need to pick some mechanics brains for a moment...04 Sportster 883, I rebuilt the carb a few months ago after having this problem....

It will start up and idle but once I twist the throttle, it will pop and backfire and never rev up. Even after rebuilding the carb, replacing the petcock, new plugs, new battery, and cleaning the tank, it still dont want to run right. Ive been a mechanic for years on cars and big trucks, but im a dodo when it comes to Harleys and small engines. This model is a carbed 883, no electronics to speak of. Hell i dont even know if this thing has points or not and if it does, i dont even know where it is. I cant find a decent shop manual anywhere.

If anyone has any suggestions, it will be highly appreciated!

 

This carb

stand by, check your messages

 

You're not getting enough fuel, did you check your fuel line?

 

You most likely have part number 43 upside down - very common mistake. Here is a link to the pic. You can look into the carb throat and verify. Tapered side must be up facing needle.

https://cv-performance.com/harley-cv...-tuning-issues

 

it was running this way before i rebuilt the carb. i had the dealer print off a copy of the schematics before i even touched it. thanks for the info!

 

installed new lines

 

If that is the case, I would ask how you determined it was the carb. It could easily be ignition related as well.

 

its just the way it was acting that led me to believe it was a fuel issue. the bike has never been worked on except normal maintenance. but im believing now it is ignition, but im not sure.

 

With the air cleaner assembly off, start it up. Watch the vacuum piston. When you gas it, the piston should move up and down.If not, take off the vacuum cover (#2) and inspect the diaphragm for cracks or rips.

 

Check intake seals for vacuum leaks. As far as manuals go,try to find a H-D service manual. Clymer also makes a good one, you can find them on E-Bay.