I'm new to street riding and to Harley's, so I have a newbie question regarding the idle speed, back firing, octane and overall power.

I purchased a used '04 883 Sportster a few months ago. The bike already had the Stage 1 mod and SE slipons added to it.

After taking it in for the 1k mile check up, I noticed that they adjusted the bike to idle a lot slower than when I took it in. (In other words, when I got the bike back it took a while to get use to the fact that it's not going to die out when waiting at a light but that it just had that nice, slow, Harley idle.) I'm not sure how slow/fast these bikes should be idling (it doesn't have a tach), but it sounded as if it was adjusted to idle as low as possible. I figured this may be a normal adjustment after a bike's initial break in period (didn't think to call and ask, just figured it was normal).

The bike still had what appears to be normal carb farting problems (H-D said this was natural for the stock carb?), as well as occasional muffler back fires. No problems with power on the low end, but it seems as if the top end power was not all there (perhaps this is also bc it's an 883- you tell me!), and the backfiring really bugged me.

Now, 1000 miles later (2k total), it seems to be idling at the higher speed once again, still with the seemingly more often than it should backfire.

My first question is - what would cause the idle speed to change if I haven't made any adustments myself, using the same gas, etc? I haven't had the chance to research this until now, but I'm also wondering if any of this is related to my bike backfiring (from the muffler, not the carb) even after it's been warmed up?

Today, I got the bike up to about 80mph and seemed to really be pushing it. I also smelled a strong gas smell at that speed as if it wasn't burning completely or cleanly, and giving more gas seem to only bog it down as if i was flooding it (btw, I don't think this is a case of bad gas bc I've had a number of tank refills at different gas stations, but you tell me!).

I've been tempted to change octane (87 - 89) for other reasons, but I would like to first check out while it's idling high, why it changed (weather is the same here in Tx - hot!), and if I'm losing top end power bc of it.

What do you think? Check my service manual and adjust the idle screw (if there is such a thing on a Harley)??! That shows you how much I've worked on these bikes.

I've also read a lot of posts about octane and it seems people each have different results going from 87 to 89. I would like to get the idle and backfire problem solved first before adding any other variables into the picture, but I can't help but to wonder if it would be worth a try to change to 89 octane.

Synopsis of my questions: First, I am curious to know about the idle speed and why it would change. Second, what to do about the backfiring and is it related to the idle speed. Third, why would I feel 80 mph was really pushing it, and if I would give it more gas, it seems as if it was flooding it? Sorry for the long post and so many questions.

 

I too am at the same point with my '01. I would be interested in hearing some answers here. For me it is about 20 degrees colder than the late summer temps we were having so I kinda wrote it off to that and the fact that I think it really needs to professionally dyno'd and tuned.

 

First off the idle speed should be set around 950 to 1050, I have an 03 1200 and the service manual tells me to set it at 1050. If you don't have a tach, the only way you can set it is to take it to the dealer and have them hook up their diagnostic tach or you could do the idle drop setup. If you read the DIY Fuel/Carb related you will find how to tune the carb and do the idle drop. You might think the idle has changed but unless you changed something it probibly hasn't. If it's coughing out the carb it is probibly still too lean on the slow jet or the idle air mixture screw. I run drag pipes with baffles and a SE air filter and had it jetted good (45 and 2.5 turns) then I modified the baffles for a little more sound and had to rejet again (48 and 2 turns) to stop it from coughing. I can hit 70 MPH in third gear with a little throttle left. I haven't had it any faster, I don't need to, I had a good plug reading so I know I'm not rich on top. The hardest part about buying a used bike is you don't know exactly what changes were made. If you can't get the bike over 80 and the throttle is flat, you probibly are running rich on the main jet or needle. The best thing you can do is read everything you can about the CV carb, take it apart and see what changes were made from stock and see if you can improve upon them or go back to stock settings and start over. There are alot of good sites on the web about the CV carb http://www.nightrider.com/biketech/hd_cv_mods.htm is one and there are others, all I can say is read, read, read. Just my .02

 

i did about 100 miles home from the shore this past w/e and did 85-90 the whole way. bike still had passing power left, i know i used it a few times. if your bike is boggin at 80 i would do what john said and check the carb. make sure everything is clean and free of gunk then check the jets and see what sizes you got in there. i believe i got a 48 clow and left the main alone. i am 2 turns out on the mix screw. its starting to get cold so maybe a nice winter project is in store to teat stuff apart clean it out. if you got the 1k done recently on an 04 then your bike did some sitting for two years.