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Discussion Starter #1 (Edited)
I've been doing a DIY Stage 1 on an 03' 883 Sportster........de-baffled the OEM mufflers, installed an Ultima free flow filter (similar to a K&N) in the OEM air cleaner and discovered that a PO had re-jetted the carb with a Keihin Stage 1 kit (the main jet was one size smaller than most folks were recommending- a .165). Now my thinking, the plugs (new, stock plugs) looked a bit lean so I raised the main needle .050 to richen it up a wee bit. Went for a ride yesterday and read the plugs when I got back....better but still looks a bit lean to me. I have the next size larger main jet (.170 which most of the HD guys were recommending). What would you think of putting in the larger main jet and a more free flowing filter (UNI foam in the OE assembly)? Still going to be lean? Maybe just the jet and read plugs again (my thought)? Get the next two sizes up (.175 & .180) just in case?

The lower end (idle) is great and the bike starts almost as good as a FI bike. It runs fine up to 80-85 and then just levels off. No tach so I'm not sure what rpm that is (some folks are saying that an 883 with stock gearing that would be 45-4700 rpm). Engine stops counting at ~ 5400 from what I've read. I've never hit that. Over-all a nice riding bike. I just want it to be reliable.....no burned pistons or valves.
 

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Not a Cab guy here, the last time I worked on a Cab was my 1950 VW.

Hope you get the setting right.:goodluck:
 

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Sounds like a freer flowing air filter would compliment the de-baffled exhaust.

Do you know if the stage 1 jet kit included a new needle?

The CVK 40 on my KLR responded better to a richer needle from a different bike than it did a larger main jet. I think that was cause I rarely ride at wide open throttle, so I hardly get up on the main jet.

My $.02 is focus on the needle if you ride the bike mellow, go for the bigger main and maybe a richer needle if you ride it hard.
 

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I had an 03 Honda CR250 dirt bike. They were notorious for not carburating correctly.

After fiddling around with jetting and needle positions I finally broke down and purchased a JD jetting kit for it.

Wow do those guys know their stuff. It came with a pilot and main jet plus a needle.

That little bike ran like a stripped ape after installing their parts.

Don't know if they do Harley's but might be worth checking out.
 

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Discussion Starter #5
Sounds like a freer flowing air filter would compliment the de-baffled exhaust.

Do you know if the stage 1 jet kit included a new needle?

The CVK 40 on my KLR responded better to a richer needle from a different bike than it did a larger main jet. I think that was cause I rarely ride at wide open throttle, so I hardly get up on the main jet.

My $.02 is focus on the needle if you ride the bike mellow, go for the bigger main and maybe a richer needle if you ride it hard.
Yes, the Keihin kit had their version of the 88' XLH needle which was a "no accelerator pump" type needle. Recommended by the HD guru's for a a Stage 1 (much richer profile than the OE Sportster needle). I also enlarged the vacuum hole in the slide (recommended by the HD guru's). These same HD guru's suggest raising the needle with up to 5 .025 washers. I've got two on there now.....but they also recommend using the .170 jet. Some folks have used jets as large as .185...I'm thinking install the .170 jet and check it again (when the weather is good enough to ride). Then see about the different air filter or raising the jet at least another .025....
 

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If it is lean and you intend to further open the intake or exhaust that leanness will be accentuated. More airflow = leaner fuelling.
Remember that all can be good at one throttle opening but lean at another. The most potentially dangerous is a too lean main jet.

Rule of thumb:
Idle Jet = idle and off idle
Needle = 1/4 to 3/4 throttle
Main Jet = 1/2 to full throttle

The engine transitions across the three fuelling systems as the revs and throttle increase.

That said, I have no experience with Harleys. Look here for some advice from Keihin: http://www.keihincarbs.com/tips/gate.html
And general jetting 101: Overview: Jetting 101 | All-OffRoad.com
 

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Something I'll mention is that Duffy lives in the high country of SD at about 3700' elevation.

Hi Duffy. Say high to Mrs. Duffy.
 

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Discussion Starter #8
Something I'll mention is that Duffy lives in the high country of SD at about 3700' elevation.

Hi Duffy. Say high to Mrs. Duffy.
Hi Steve........I did forget to mention my altitude didn't I? Mrs Duffy says "hi" back.

Brockie.....I'm trying to do this in logical small steps so I can keep track of results. I think that the next larger main and check results. Still lean then I'll add another .025 washer under the needle.....if I happen to get too rich then I'll try the other air cleaner. I should mention that these filters are actually a bit more restrictive than a Screaming Eagle air cleaner assembly (true HD Stage 1 equipment) cause it still utilizes the OEM filter housing. Thanks for the info all.
 

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You definitely need to take the elevation into consideration, and richer with an easier breathing engine is the way to go. Injected engines adjust themselves for altitude and air pressure. Unfortunately carburettored engines do not.
If you are time constrained and fussy the real cure is a dyno session. Those guys can tell you straight off which parts of the fuelling system need adjusting.
 

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Discussion Starter #10
You definitely need to take the elevation into consideration, and richer with an easier breathing engine is the way to go. Injected engines adjust themselves for altitude and air pressure. Unfortunately carburettored engines do not.
If you are time constrained and fussy the real cure is a dyno session. Those guys can tell you straight off which parts of the fuelling system need adjusting.
A dyno session would be nice.....there may be one in Rapid City at Black Hills HD but like most dealers they are way overpriced on everything. Plus it's 70 miles away.
 

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A dyno session would be nice.....there may be one in Rapid City at Black Hills HD but like most dealers they are way overpriced on everything. Plus it's 70 miles away.
If you strike issues they are the cure. After putting an after market pipe on one bike and playing with various jets I still had a lean spot, so after many tries I took it to the dyno and got it back perfect.
 
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