I have finally started working on a sportster I picked up a few years ago. It is back firing and running rough. I can pick up a new S&S Super E for about $380.Rebuild kit is $90. Any thoughts on this.

 

I assume you mean the rebuild kit for your existing carb is $90? Wow, seems extreme. Maybe shop Ebay for a better deal?

You can easily retrofit a later style CV40 carb instead of the (non-accelerator pump) butterfly carb you have. CV40's are cheap on Ebay, and so is a later manifold and mounting bracket. Just another option.

Also, rebuild kits for the CV40 are about $20.

John

 

Seeing rebuild kits for $27 for existing carb

 

S&S Super E is a good carb. What do you have now?

Back firing is probably due to intake or exhaust leak. Clamps securing manifold and/or exhaust clamps/flange may just need tightening up. My bike ran crappy when i had an intake leak i.e. popping and bogging.

If you eliminated your leaks and you are still running crappy, your carb probably needs a good cleaning. Make sure you have good fuel flow. Then remove the float bowl and the jets and soak in something like this...make sure you buy float bowl gaskets before you reassemble.


Shoot some carb cleaner up into every fuel port into the carb.. Since I do not know what mods you have done, it may be running rough because it is not tune properly....so you can try changing your jets if it still runs rough after the cleaning.

 

The bike has a Super E in it now. It sat for several years. I flushed the tank with new fuel. Not sure how it ran when it was put up. Motor is stock 883 with straight pipes. I will check for tightness today. I had planned on changing the exhaust .If it is popping thru the rear cylinder does that indict rear cylinder exhaust leak?

 

If you have a Super E, why would you buy a new one? No brainer, get a carb kit and rebuild the carb.

Yes, popping could be an exhaust leak. Probably prudent to change both intake and exhaust, eliminate some fundamental issues.

John

 

If you tighten and still leaks, then change the seal...not sure if you have o-ring or rubber band type. Also make sure you have a support bracket for the AC. Good move to replace the straight pipes...very difficult to tune.

Check out this vid on S&S super E and drag pipes

Here is a S&S vid on jetting and tuning a Super E

 

FYI, the Super E carb is a little too large for a stock 883. I don't think it will ever run like it should with it.

 

I have a Super E myself. Great carb, and easy to tune.

Having said that, there is one huge issue with them. People tend to crank down on the mixture screw and crack the throttle body at the orifice in the venturi. If you have a crack in the body, you will never get it to tune properly and it will cause all sorts of issues.

Before you waste a bunch of time, take a good look at the orifice where the mixture screw seats. If you see ragged edges around that hole, or a crack coming from it, you will need to replace the throttle body. Ask me how I know.

Good luck.