So I bought the 96 savage with a RYCA bobber kit pretty much installed. Got it home and took just over a month cleaning up wiring, working out the bugs and getting it cosmetically in shape. Not knowing what all mods had been done I slowly started to break into the internals to have a look. Replaced the cam chain tensioner with one of Verslagen's cause she was out about 18mm.

I ordered a jet set from Lancer not really knowing if the carb had been cracked open but with the way it was running took a shot in the dark. At about a 1/4 throttle held in place there's a terrible miss. I started by replacing the spark plug. It wasn't in terrible shape. Had some black to it but dry.
Current mods are as follows: elbow with cone filter and RYCA header with their reverse cone muffler original baffle inside.

Brass plug had been removed and upon investigation learned it was 2 turns out. When I cracked the carb open today I found 3 washers and a 152.5 main jet and a 55 pilot.

If the stock main is 145 and the pilot is 52.5 that would be 3 steps up on the main and one on the pilot.

I've read Lancers carb tuning and Serowbots tuning what seems like 100 times each and I can't for the life of me figure out why that particular setup and why it has the terrible miss/surge at 1/4 throttle.

The bike has 18k miles. Good compression. Valves have been adjusted correctly.

At 3/4 turn she lights up like the 4th of July and has no issues getting out of her own way. Unfortunately I dont ride at 3/4 throttle I ride at 1/4 throttle right where the god forsaken problem is.

Any input would be greatly appreciated.

Side note. I cleaned the carb today while I had it apart and put it back together as it was but with the new jets of the same size as before. I want to see if a possible clog was the issue since someone already jetted it and may have had it tuned correctly and it was just dirty.

I know I have a small exhaust leak where the slip on and header mate up. That will be remedied this coming week with a new custom exhaust. From that point I will embark on tuning it again.

Well yuck,...  

Tuning is an incremental thing...
Many people want radical improvement, and think that a radical boost in jetting will give radical increase in power...
Not so...

I would start decreasing jetting,... particularly on the pilot...
...and the intake set-up sounds like fashion, over function... (if you don't know what you're doing, you can booger up performance with wishful mods... any pics?)....

When you say "there is a terrible miss"....can you tell if the engine is blubbering as if there is too much fuel - or surging as if the mixture is lean?

@Serowbot here is a pic of the filter setup. It's the RYCA elbow for the cafe builds. I didn't like how the cone was basically stuffed between the underside of the solo seat and the fake oil can for electronics. This change did nothing however with the way it's running. If anything it actually helped a small amount.

@Gary that was my intended 1st plan of action. I'd like to give the PO the benefit of the doubt and say it was jetted this way for a reason. So I'm gonna start with a washer removed.

@Dave. I really wanna say it's surging. It's like hesitate/jump continually unless I turn the throttle a bit more then it clears up

@WD I did check the cap on the vacuum petcock because I was curious why one was covered yet 2 were left untouched. It's in good shape but I replaced it anyways.

Gonna fire it up now, get it up to temp and adjust the idle mixture and see how she does with just a good cleaning. I plan on starting by removing a washer. If that doesn't help I'll go back and start adjusting jets up or down. Gonna be a fun ride for sure. I have a tach/speedo combo coming any cay now so I will be able to use the tach to help tune.

Thank you everyone for the input. One thing I forgot to mention last night in my 1am delerium when I start her I use 1 click on the choke. Ride away she runs spectacular. It's how I can tell te choke has shut off as soon as it closes I immediately feel the surging. Pull the choke back out 1 click and boom runs perfect.

Man I hope that's it. Here's a pic of the spark plug. Has about 400 miles on it. Some black around the end threads and looks a bit burnt on the tip. About to fire up now I'll post up shortly.

For the purpose of determining mixture/carb settings, it's difficult to read a plug with 400 miles on it. What you are reading are many warm-ups on choke and every possible throttle setting. Where is it rich...where is it lean...who can tell?

If you want to perform a "plug read", it's best to start and warm-up the bike on the existing plug, swap-out to a new plug, perform a throttle position run (i.e. 1/2 throttle), and then review the plug.

This method works great for a dirt bike (easy access to plug) but is a bit cumbersome for the S40. For your S40 you are better served with a "seat-of-the-pants" calibration of the carb.

Seriously wtf!

Come out of work tonight like always, pull the choke 1 position and fire it up. Seemed like it was idling super high for just one tab on the choke. Let it run for a bit hop on and head home. Get about 2 miles down the road and choke disengages and it's immediately surging. Get to a light and it dies. Fire it back up and hold the throttle just enough to produce a steady idle and it popping in the carb. Get it home surging all the way and as I turn to my entrance I shut it off and pow a huge backfire that set off a car alarm in someone's garage.

I haven't changed anything since it was adjusted today. Road it to work and it was fine. No popping no backfires hell it didn't even poof when I shut it off now it's spitting and sputtering and what seems like backfiring in the carb. What the hell did I do?

@WD
As far as I know the bike hasn't sat for more than a week or so without running. As far as gas goes I use Mobil 90% of the time because that's where I have a gas card.

The only variable that changed from the time I left for work till the time I got off was temperature. It a as low 70s when I rode there and upper 50s when I left. Something's definitely not right. It was idling way higher than usually with the choke on. And it was for sure backfiring in the carb. That boom when I why it off was loud enough that it set of a car alarm in someone's garage.