To start off I’m new here, and I came to get some insight from some of the old head Evo guys and the dudes who know what the hell they’re talking about. I have followed this forum for some questions here and there, but I almost always see very helpful and positive suggestions and very knowledgeable insight.

Currently, on my personal 99 Softail Custom, 80” evo, I’m running 10.5:1 wiseco pistons at .05” over, Andrews Ev46, S&S adjustable Pushrods, Super E carb, S&S intake plenum, new style S&S crankcase breather gear, Accel supercoil, .030” cometic MLS head gaskets, NGK plugs, mild head porting and polish, all done By yours truly. I put about 800 miles on the bike in the last two weeks. No major issues since the rebuild and break in period. I’m not having many issues or anything with it, It Runs incredibly well on 93 pump gas, except for one minor flaw.

I have the air/fuel about perfect after checking the plugs after some 70mph for about a 4 second count at WFO then shut it down - “plug runs”. I have pretty decent throttle response, even with a velocity stack and custom “tuned” 2” “drag pipes”. I was going for good lower-mid range to top end power and a decent rev ceiling, I wanted to really wake up the stock evo, which I’ll get to in a moment. No fine flake in the oil after 3 oil changes and 800 miles, no pinging, no knocking nothing. I’m sure I’m forgetting details, I’ll answer questions as long as it leads to a solution.

I have a mid rpm stumble, only if I rip the throttle wide open after about 1500rpm or so, BUT If I roll into the throttle it doesn’t really happen. Just a couple hiccups here and there on its way to running like a raped date in the mid to top end.
I’m Guessing this is due to the velocity stack, and If I cover the rear quarter of the stack with my knee, the stutter is less prominent. Once I get into the band where the cam starts to really work, it pulls HARD. I’m going to try to switch back to the kuryaykn Hypercharger that was on the bike before I did the upgrades. It runs like a singer at 70 in 5th the way it is and is a blast on the highway with little to no misses, unless I try to go from a mild cruise to WFO. IT doesn’t hesitate leaving idle at redlights or anything like that unless I crack it wide open. Really I’m just trying to make sure I didn’t forget anything. I’m looking to cross my I’s and dot my T’s - HAHA. Im not experiencing an ignition timing issue, right? I used a timing light with a mark on the alternator housing inside the primary once I got it back together and it’s damn close. Again I’m not a professional tech or anything but I’m pretty proud of what I’ve done with it. It does run exceptionally well besides the weird stutter under heavy throttle from low rpm up. Say for instance, if I leave a light and crack the throttle, that’s when it does it and doesn’t really clear up unless bail outta the gas and roll back into it all gentle like. If I’m cruising at 35 or 40 in 3rd and crack on it, it stumbles, still accelerates but cuts and carry’s on, unless I let off and roll back in. If I’m in 5th and busy it wide open it struggles the same way and I’m kinda tired or scratching my head about it. Once I get up around 3000 rpm it’s game on, I can roll it to WFO until I run outta revs, fast and smooth as butter. Like I said, it pulls hard as long as I baby it outta the hole.

if anyone on here has any insight as to what I should check, my hunch is the velocity stack was a dumb idea, that it creates turbulence or is giving the thing way too much air in that initial 1500k to 3200k range. but it was cheap and I like the look of them honestly, even though I know that they are known for terrible throttle response and sporadic lean conditions. Any suggestions? Seriously, Any help would be appreciated.

 

I have a 99 heritage. Rebuilt .020 over, Wiseco forged pistons, dynamic balanced crank assembly, heads ported / shaved, thunder monster baffles, s&s oil pump, Ev27 cam, Rivera pushrods 10.5:1 compression - .030 headgasket etc etc yadda. I had a s&s shorty e on it and tried every jet combination available. I fought it for 3-4 years. I tried everything anyone suggested and took it to 2 people that were supposed to he wizards on the evos. They would get it running good but Im sure they were not doing 75+ mph road test because it always had a hesitation or dead spot somewhere and I got about 30 mpg. I finally pulled the s&s off & dug out the old cv carb. I bought a deluxe tuner kit and rebuilt it. My bike has never ran better. Very strong and gets better mpg. I think alot of folks that have the s&s shortys are probably hanmering them red light to red light and think they are perfect, but if they had them on the 75-85 mph pulls would realize different.