I have an 03 sportster 883 with 8k miles. Had a K n N air cleaner on it when I bought it and I recently put a set of 2inch straight pipes on it, other than that it's stock, or so I thought...I'll get to that.
When I got the bike (K n N air cleaner stock exhaust) I was having problems keeping it running at idle. Start fine, warm up fine, once I rode for a while and stopped at a stop sign seemed to load up. I played with the idle a little but never seemed to be able to get it quite right.
The beginning of this riding season I bought a set of 2 inch straight pipes, serviced the bike, to include new plugs and my idle problem seemed to be fixed!! I was sure I would have to jet it to make it run right, but it ran great compared to how it had been running. Still a little sluggish in the bottom end, but man she'll scream on the top end.
Fast forward to this weekend and I got a hair up my but that I could make this thing snappier on the bottom end if I changed jets. Did some reading and found how to tune/rejet the carb. "Start with adjusting the mixture screw" so I went to the garage, expecting to find the "factory seal" on the mixture screw and it was gone...hmmmm.
Also learned that I should start with a fresh set of plugs. Pulled my plugs, with 3k on them, and they were black, I mean coal back...not wet, not oil, just black, which means rich...right?
So, new plugs, turned the mixture screw in till it just touched and backed it out 2 turns, set the idle at 900 rpm and went for a short ride to warm it up. Turned the mixture screw in waiting for the engine to cough or struggle....never did. Bumped the throttle a couple times with the screw the whole way in and I noticed a puff of black smoke (rich). Took it for a ride and if I ease into the throttle she loves it, crack her open from a "rolling stop" falls on her face. Spent the next hr playing around with fine adjustments trying to get it adjusted but no luck.
So I got curious, pulled the plugs, black again (rich) got more curious and pulled the jets. 45 slow jet and 160 main! If I'm not mistaken these came stock with 40 and 160. From the reading I've done these bikes should run well on a 45 slow jet. So all that for this...
Do I back the slow jet down a couple sizes or do I have something else going on. Also, I think I'm a little lean on the top end as my pipes are "bluing" up near the exhaust ports. Is this a good indicator or is it normal. Thank you
When I got the bike (K n N air cleaner stock exhaust) I was having problems keeping it running at idle. Start fine, warm up fine, once I rode for a while and stopped at a stop sign seemed to load up. I played with the idle a little but never seemed to be able to get it quite right.
The beginning of this riding season I bought a set of 2 inch straight pipes, serviced the bike, to include new plugs and my idle problem seemed to be fixed!! I was sure I would have to jet it to make it run right, but it ran great compared to how it had been running. Still a little sluggish in the bottom end, but man she'll scream on the top end.
Fast forward to this weekend and I got a hair up my but that I could make this thing snappier on the bottom end if I changed jets. Did some reading and found how to tune/rejet the carb. "Start with adjusting the mixture screw" so I went to the garage, expecting to find the "factory seal" on the mixture screw and it was gone...hmmmm.
Also learned that I should start with a fresh set of plugs. Pulled my plugs, with 3k on them, and they were black, I mean coal back...not wet, not oil, just black, which means rich...right?
So, new plugs, turned the mixture screw in till it just touched and backed it out 2 turns, set the idle at 900 rpm and went for a short ride to warm it up. Turned the mixture screw in waiting for the engine to cough or struggle....never did. Bumped the throttle a couple times with the screw the whole way in and I noticed a puff of black smoke (rich). Took it for a ride and if I ease into the throttle she loves it, crack her open from a "rolling stop" falls on her face. Spent the next hr playing around with fine adjustments trying to get it adjusted but no luck.
So I got curious, pulled the plugs, black again (rich) got more curious and pulled the jets. 45 slow jet and 160 main! If I'm not mistaken these came stock with 40 and 160. From the reading I've done these bikes should run well on a 45 slow jet. So all that for this...
Do I back the slow jet down a couple sizes or do I have something else going on. Also, I think I'm a little lean on the top end as my pipes are "bluing" up near the exhaust ports. Is this a good indicator or is it normal. Thank you
