Answered my own question; coil is bad too.

 

Should be good as new now.

 

My experience, I opened up the intake (K&N) and performance slipons. I kept the carb jets stock, 45/195, but the needle got two #4 brass washers installed under the "spider". This lifts the needle just a tad quicker off the taper portion of the needle. Stock air/fuel mix was 2 1/2 turns out. Now 95" kit with 203 cams, the A/F screw came out an extra 1/4 turn. Don't know the comparasion grinds of your cams to mine, but on a recent two up trip we got 47 mpg on the highway and 40 around town. MPG is directly related also to the twist of the throttle. Your plugs will also tell you what your mix is.

 

I will not get the replacement parts until later next week, and will post an update after I install them. I need a Screaming Eagle Coil which complicates matters a bit.

Once I get my ignition issues resolved, I'll turn my attention to the needle.

I know it is off-topic, but ... I believe that the SE 203 and the S&S 510 are very similar cams. Back in 2001, I replaced the original cam plate because of the bearing problems. At that time, I also upgraded to a 203 cam. While I could feel a performance difference between the stock cam and the 203, I do not feel any difference between the 203 and the 510.

 

Has your slide been drilled? Im running 48 slow 195 main with a sporty needle and i get 40mpg consistently. Im thinking other mods have been done to your carb. Im 285 lbs and ride pretty aggressively.

 

'98 Springer Softail here, running a Ness Bigg Sukker and Hooker Rebels with competition baffles. Altitude fairly low here in NC. No internal engine modifications. Pilot jet is 48 set @ 3 out with CV Performance EZ adjust thumb screw. Mid and high are Dyno Jet with drilled slide. Would have to check the box for missing contents to verify size used but mid and high are fine. Gas mileage is not an issue...I'll fill it when required. Even with the 48 I'll get a lean pop occasionally. It happens when approaching a stop and downshifting. I'll usually rap the gas when doing so. Bike runs well and plugs read a shade lean. Gonna stab a 50 in there and hope that clears it up. Recently reveiwed an article by Tom Johnson and he suggested a 50 may be required. I'm gonna try and see.
When I ordered the thumb screw needle I also ordered a packing kit to include an o-ring/washer/spring. There was no o-ring or washer present in my carb and the factory service manual gives no pic of the idle mixture needle. I'm running the o-ring and washer and all seems well. What's the deal with that?? Are they supposed to be in there or not??

 

I do not know. I have not yet opened the carburetor top. Would not surprise me if it was drilled. I am unsure of the purpose or advantage of drilled slide.


Similarly, my original mixture screw lacked the O-ring and washer. I installed the packing kit too.


I am begining to wonder how long my wires and coils have been bad. Out of curiosity, I wonder whether my previous rich condition somehow masked the wire/coil problem. More to the point, I also wonder whether the wire/coil problem has skewed my results with leaner jets. Is it possible that I will be to lean with a proper functioing ignition system? I plan on making only incremental changes, and will make changes to address a lean condition if it occurs.