Harley stock pipes and modified CV carb

Hello everyone,
I'm new here and just came across this site while I was looking for information on modifying my Harley CV carb. This site looked like a good place to get some expert advice on my 2004 Harley Sportster 883 custom. I'm an old guy who has been riding motorcycles on and off for over 43 years and just purchased the above Harley, used, in pretty good condition with the exception of some minor problems. I'm not real familiar with Harley's since this was my first one so the first thing I did was buy the Harley Service manual for my bike. When I got the bike home I noticed it running super rich, blowing out alot of black smoke from the exhaust, backfiring, and it smelled like raw gas. I then went to the service manual and noticed that some of the stock parts were changed such as the exhaust pipes, air cleaner, and large jets to the carb. My intention was to go back to the original configuration of my Harley so I purchased stock exhaust pipes, stock air cleaner assembly, and took out the carb and replaced the jets to what the book called for. I put in a #42 slow jet, and a #170 main jet and cleaned out the carb. I replaced the plugs, changed the oil, filter, and transmission oil using all harley parts. It started right up but backfired thru the carb eveytime you quickly throttled the engine so I adjusted the mixture screw to about 2 turns out and played with that for a bit but still got backfiring thru the carb on and off. I wondered if going to a larger slow jet might help this problem or not. I also wondered if I went to a Stage 1 carb kit and high flow air cleaner, could I still use my stock pipes. I kind of like the lower noise level of the stock pipes verses the straight thru, no name pipes that were on it. I also noticed when I went to put on the stock air cleaner backplate that it didn't lay flat across the area which it mounts to. When I put the backplate over the carb and lined up the breather holes then put in the breather screws it bent the left side of the backplate so it was curved and thus not allowing the air cleaner cover to properly seal right. I didn't find anything that the backplate was hitting and made sure the carb was pushed all the way to the rear into the intake rubber coupling. Then I figured maybe I should just get one of those higher intake air cleaners which may work better. Anyway any advice would be appreciated on if you think I can use my stock pipes with a high flow air cleaner and Stage 1 carb kit.
Thanks alot everyone

Welcome and I'm sure the experts will chime in. Until then if you go to the site navigation menu at the top left of this page and click on "tech tips" there is some very good info on tuning carbs. Not sure why you back plate is not seating properly, unless it's not the stock carb. In any case there are many people with sporty's on this site that can help. Ken, aka kenfuzed, is the carb guru.

Hope this helps.

Thanks for the welcome ringo912. The first thing I checked was the carb being the right one, and it was, according to the book and carb that was on it. A Harley CV with the proper part number sticker still on it for my year and model. Anyway thanks again and I'll navigate around on this site to see if anything matches my carb problems.

Take care and thanks again.

Hello and thanks chucktx for the welcome and information.

I noticed when I was adjusting the carb that the backfiring was less as I raised the idle just a little. I know the book said the idle speed was to be between 950 and 1050 rpm's but my harley only has the one speedometer guage and I kind of have to guess the rpm's. I also checked the air cleaner backplate part number stamped on the air cleaner and it is the one that was shown in my dealers part book for my year and model. Being that I purchased the bike used and obviously someone has changed some parts which I am changing back to stock, I think I'll take off the air cleaner assembly again and remove the intake manifold, and take it down to the harley dealer to see if it is the correct one for my bike. Being that I can't get the backplate of the air cleaner to fit flat against the engine and carb without bending on its sides I figure maybe the intake manifold is out too far thus keeping the backplate from fitting properly. I'll replace the intake seals going to the heads at the same time. I'm glad I got the service manual as it really is a help in assembly and dissassembly of my harley. I was actually surprised at the simplicity of the CV carb when I was into it, cleaning and installing the stock jets and all. Kind of reminded me of the old carb on my 60's lambretta I used to have. Anyway thanks for the info and I'll probably just remove the intake manifold and take it to my harley dealer and let him verify if its the proper stock intake for my model harley.
Take care

The 883 is natorious for having a "sportster cough". The stock #42 jet is too lean and can only keep the EPA happy. They are much happier with a #45 jet and the A/F mixture screw turned out to 2 1/2 to 2 3/4 turns. Set the idle up to 1050 to 1100 rpm. When you first start it, let it warm up with the enrichner on for about 1 to 2 minutes. Ride off with the enrichner on and push it in after a block or so. You shouldn't have any troubles other than wondering how much it will cost to put the 1200 conversion kit on when your wrist wants to give the seat of your pants a bigger thrill.

Hey Oldman1, welcome to the site and welcome to my nightmare. If you look through the tech threads you will find my reason for being here. Like you I was trying to get a sick Sporty to quit coughing on throttle up (mine just happens to be an 05).

Like your bike mine was used and apparently to some degree abused in my case. Straight pipes (which I like the sound of just want the baffles back to please my State's DMV), 45 idle jet, but the goofball went to a 165 main and put stupid spacers under the needle. Mine had backfired through the carb so much that it actually burnt/melted the plastic on the vacuum piston.

Up to date, back to the 42 idle jet (which according to VYBR8ER will be getting changed back soon, thanks, I kept the 45 just in case), a 180 main since I couldn't get factory 175, rebuild kit all through to include all new gaskets from intakes out, new acc pump, new slider piston, new crank position sensor (apparently not needed same dang codes). Although she is MUCH MUCH better than when I got her she is still not "healthy". I have been fighting this thing for over a month (waiting on parts mostly). I wish you the absolute best luck over mine.

Oh yeah I don't know if you found it in your manual or not but just in case something I did find, is the onboard diagnostic. Push in the trip reset button on the bottom back of your speedo, hold it in while you turn the key on, then let go of the button. The miles will display "diag" push the button one time and it will switch and display PPSPt. Pushing the button quickly will cycle through the selections, while a selection is flashing holding the button for about 5 seconds (it will trip over when it is ready) will give you any codes the computer has stored. All of my codes have been under the first P (ICM) and have related to the CPS. To get out of the diag mode simply turn the key off and when you turn it back on it is all back to normal ops.

Good luck and BTW if you do get yours to work, PLEASE Share what it took and I will do you the same favor. Keep the rubber side down man.

Hello wvak47,
Thanks for the welcome and input on your problems and diagnostic information on your 05 sportster. The service manual I got from the harley dealer didn't have anything at all on the onboard diagnostics, unfortunately they make you buy a seperate book from harley with that information. I guess I'll try the #45 slow jet and see what that does. I only went with the #42 because that was what I was told was stock for that model. When I took my carb apart the plastic on the vacuum piston also had a black melted spot on it. The needle on mine was left alone and looked in good shape so I left it, I will be getting another vacuum piston and accelerator pump diaphram, along with springs for both, and have to pull my intake to see if its the correct one for my bike as my stock air cleaner backplate doesn't fit flat. I did check my float level position and condition of the fuel inlet valve which were both allright. I've been to my local harley dealer and the were pretty helpful as far as getting my stock parts and all but didn't seem to want to volunteer any service tips on the problems I have. I know they probably wanted my bike for service but that wouldn't help me to find out exactly what they had to do to it, all you get in the end is what parts were changed and labor cost, not the actual description of what was tweaked or adjusted. Also from what I've read it seems to be the norm or nature of the beast and its a hit or miss operation to try and cure. Anyway I'll keep you posted when I find out whats going on with it. It does ride exceptionally well other than the backfiring thru the carb when quickly throttling up from and idle.
Take care and thanks again.

Hello VYBR8ER,
Thanks for your input. I'll be trying that #45 jet along with re-adjusting the A/F mixture using your advice. I also have some other things to check out on it such as proper intake and or intake leaks, and replacing a few other things on the carb. I'll keep you posted to what the results are.
Thanks again.

oldman1 check your private messages

Thanks for the added info. I figured the CV carb. was a simple one, as there wasn't too much to it, it mirrored alot of the old carbs I worked on from the bikes I owned in the 60s. The only aftermarket part I was going to get was the ez adjust mixture screw because it looked easier to adjust than the current one. I believe most of the problems I'm encountering were due to the previous owner adding the stage 1 kit, straight open pipes, which was way too rich causing gas fouled plugs, heavy black carbon lining the tailpipes, and the heavy gas smell and smoke while running. I went back to the stock jets 42 and 170 and adjusted the mixture screw about 2 3/4 turns out, had to guess on the rpm's as I have no tach. Anyway I got her running but not without an occasional backfire when quickly throttling the gas. I now will be changing to a #45 slow jet and see how that works. I'm also going to replace the intake gaskets and carb to intake rubber seal/o'ring. I'm not going to take anything for granted as I want to get to a known starting point before making any assumptions or buying parts not really needed. I'm not sure the intake manifold is stock either since my air cleaner backing plate doesn't fit flat against the engine without bowing on the ends. I'll be pulling it off to take to my local harley dealer and let him confirm if its stock/oem. I'm also replacing the vacuum piston as I'm not sure it wasn't modified with the larger hole. Hopefully in the next week or so I'll have the results of my work.

I did put the EZ Adjust screw in mine and Chuck is right it is much nicer. One thing don't get too comfy with it and try to reach under the carb while setting on the bike. Those stupid jugs get a bit warm, and yes I know this for a FACT LOL.

In my first thread (sorry I dont remember who and too lazy to look) someone told me they had our problem with an 04 and 05 and it took about 4 turns out to get the air right. I know the thread is still in this section give it a run over. A lot of helpful ideas was given to me in it.

Thanks chucktx and wvak47, good to hear the ez-adj. screw is a worthwhile investment. I'm sure the larger tuning room for adj. will come in handy.
Take care.

Just ran the the DTC info for my Sportster and all sections read "none" for any trouble codes. So it looks like all the diagnostic perimeter's are without any faults. Well this makes me feel pretty good. So at least I know what isn't a problem and will go from there.
Thanks again wvak47 for that info on running my diagnostics.

DUDE way happy to hear you had all nones. You should have the rest of it figured out pretty quick then. You are more than welcome and keep us posted. I can't wait to hear what fixs yours.

Anyone know where I can get a stock A/F mixture screw vs the EZ adj. screw for my CV carb. I was going to purchase the EZ adj. until I found out they wanted 10 bucks for the shipping, thats half the cost of the item alone. 31 bucks for a screw, and you think Harley is expensive?

I have a pretty good idea where you can get one . What is your mailing address? PM it to me and I will ship my old one to you. First I have to ask a stupid question. If you were looking at the EZ adjust as a replacement, then what the heck do you have now? A bit confused there. What can you gain by replacing a factory with a factory? Me puzzled

Oh yeah I did spend the money on the EZ, and the quallity is worth it really. I don't mind paying for quallity items that I can't produce, but I can spin a wrench and ain't payin no one to do what I can do for myself. As they say "God helps those who help themselves"

Thanks for the offer wvak47, but I found a new EZ adj. on ebay for only 14.95 and 5 shipping, alot better that 31 bucks. The only reason I was going to replace the stock A/F screw with a stock A/F was the one that was in it had a piece broken off the top where the screw driver went making it hard to adjust. Looks like whoever had it before messed it up. Anyway I found an EZ adj. for what I wanted to pay for it, and thanks again for the offer.
I'll keep you posted with my results when I get all this done, just waiting for parts right now.
Thanks again and take care.