81 Sportster Running Rough
 

Hi guys. Just purchased an 81 sporty. I rode sportbikes for years, so I'm new to this engine. This bike has an S&S Super E carb. When I first got it, the engine would only run with the enricher on. During the road test it hesitated shifting through all the gears. It would periodically dump gas through the overflow hose.

I cleaned the carb and rebuilt it with a kit, installed, adjusted the idle and the mixture. It runs much better now and idles with the enricher off. Took it for a ride and it hesitates really bad on acceleration and backfires quite a bit. Should I check ignition next?
Thanks.
Nick

RE: 81 Sportster Running Rough
 

If I was running my race car I'd say the float is stuck but since it doesn't I'd say possibly some foriegn matter on the needle valve holding it open possiblly why it is dumping gas.

RE: 81 Sportster Running Rough
 

It hasn't dumped gas out of the overflow since the rebuild, so the new needle probably fixed that. Just no acceleration and backfiring when I ride it.

RE: 81 Sportster Running Rough
 

How do the plugs look? Then from there I go into an air leak, spray the intake manifold with wd-40 and see if it speeds up at idle if it does then you have a leak through the manifold.Then look into ingition issues.

RE: 81 Sportster Running Rough
 

Thanks for the replies. I ran the bike and after it warmed up I sprayed WD-40 around the manifold. Didn't make a difference with the idle. Pulled the plugs. They are Champion H8C and look black and sooty, so if I remember correctly, its too rich. I just checked the plug. My year calls for Champion RL82YC. Maybe the plug is the problem. Thoughts?

RE: 81 Sportster Running Rough
 

If you are running with points ignition use H8C but if you are running with electronic ignition use RL82YC... I recommented first change new plugs then check ignition timing then adjust mixture S&S page has good instruction for that

RE: 81 Sportster Running Rough
 

It is signs of a rich condition,your plugs could be too cold.Put the correct plugs in and see where that take you.If that doesn't solve it you may have to go down a jet size.

RE: 81 Sportster Running Rough
 

I haven't checked the ignition, but I'm assuming its got the stock ignition. I'll pickup some plugs and try that first.
Thanks.
Nick

RE: 81 Sportster Running Rough
 

I would think it has conventional point system also besides the plugs appear to be a likely candidate,especially if the plugs for an electronic system run colder.

RE: 81 Sportster Running Rough
 

Update: I pulled the plugs this morning and put in HD 4R5s. The bike fired right up and is running better than I've ever heard it. Didn't get a chance to ride it since its pouring rain, but I'll update after I take it for a ride. Thanks.
Nick