Just when I think I understand...

I'm running 55 pilot and 155 main with stock airbox and dyna exhaust (all from previous owner) and I'm definitely too lean mid throttle.

I was going to try some washers, but I guess I'll start with no spacer and see what happens.

I suspect I'll find myself in D. Jim's position of running fine, but low gas mileage.

-D. Dwarf

DJ - Very well described. Id use it as a Jetting 101 guide. Possibly to be thrown into the Tech section. Altitude will probably throw that off to an extent as will individual bikes themselves but as a basic guide its very handy. Humidity also plays a considerable role, at least in my area. When it's very humid i can definately tell the bike is running a bit richer, though not to the extent that rejetting is needed for rainy weather. In my experience, as far as the spacer goes, it really depends. Some people have removed their spacer altogether to have their bikes bleed gas out of the airbox at idle without touching the pilot jet(i think the airbox. I know people have reported gas bleeding out of somewhere due to this. No spacer works for my bike but it does better with 1 washer (and i suspect it will do better with 2 washers ie half spacer ) owing to the fact that Im too rich with a 55 bh pilot no matter what else is going on - back to 52.5 w/bh - with that im far out on the adjust screw but i have managed to eliminate the shutoff backfire. 52.5bh and no spacer creates sluggish acceleration. Add to this a 155 main and it makes for an all around crappy ride. So I added a washer ( 52.5bh, 1 washer, 155 main) Mid range was much better but it was very apparent when the main circuit kicked in. Still no shutdown backfire. Changed the 155 to 152.5. Idle good, midrange good, main circuit kick in less evident but still noticeable. Switched the main to 150. This is where I stand now - 52.5bh,1 washer,150 main. I still have just the slightest hesitation on the main circuit. I did 4 plug reads between all this. Once for each circuit and the one im running now which still shows a bit rich. I ride mostly mid range so that tells me one more washer may do me good. I could go to a 147.5 main probably instead but while that may eliminate the rich midrange im pretty sure it would make the main circuit too lean. Only by a bit but Im in no hurry to burn up a valve like some have done. I feel another washer would lean the midrange to where it should be and lean the main circuit just enough. A 147.5 may be in my future though. Basically it all overlaps to a fair extent and its a PITA to rejet no matter what. Your observation relayed the basic information found in a dozen or more posts from years ago in one quick easy to read guide. Anyone thats rejetting though will still have to have a starting point (stock jetting with a stock bike or as rich as lancers kit allowed with my SE, which has a baffle but might aswell not have. I can see right through the thing). From there it's best still to pay attention to the bikes feel aswell as do a plug read for each circuit starting with the pilot and working up. Still going to have to open the carb up a bunch of times and take the tank off a bunch of times. It all comes down to trial and error within a certain range of possbilities and Im not the only one thats remarked that this carb never seems to be JUST right. I believe someone here wished they made a 53.5 pilot and I would agree. Or a 148.75 main. If you're rejetting you're rejetting for economy or power. Suzuki's pretty much played out the economy side so...if your doing it for power you might aswell do it right and get the most seamless transition between circuits as possible, and thats no fun...although for me it became fun. With my raptor petcock i can go from seat on to rejetted and seat BACK on in about an hour with all circuits changed. I switched from no spacer to 1 washer in a friends driveway at a party in the dark in 45 minutes (I lost the remaining bits of lancers jet set. Too much wine). Im pretty proud of myself though.

Dwarf - I'm guessing you'll want to drop to a 52.5 with bleed holes and adjust the mix screw, a 152.5 main, and 1-2 washers. No telling really without doing it step by step. 55, no spacer, 155 is pretty rich all around. I don't think you'll like it but it will probably run. 52.5 ad adjust will probably be good, with no spacer will probably be okay, with  155 main will probably be rich. Add 1 washer and you're pilot will probably still be okay with a mix screw adjust. You're midrange will probably be better. Your main circuit will probably still be rich. Add 1 more washer your pilot may still be good with mix adjust.
If so your midrange will be even better. Your main circuit will be way to rich. You'll feel it bog down at high revs. Switch to 152.5 main. Hows that suit you? Do a plug chop on the main circuit. Still rich? Go to 150 main. Check the plug again on the midrange. If it's lean remove one spacer.

I've been typing and aditing for two hours to try and get this across simply and to be honest its just trial and error. Dwarf. Pm me as you go along and I'll help you out.

I got some pilot jets in the mail today. I should be getting the stock 52.5 today or tomorrow that Lancer hooked me up with since I couldn't find mine.  

Here's all the pilot jets I have now:
50 w/ bleed holes
Stock 52.5
52.5 w/ bleed holes
55 with no bleed holes
55 w/ bleed holes

For main jets I've got:
145
147.5
150
152.5
155

On Dan's motorcycle and repair site, he said he's seen some bikes that don't run worth a flip if there is even a crack in the airbox while others run fine when opened up.  The LS650 is one of those that runs fine when opened up. I don't know if it translates into more air into the carb though or needs different jetting than one with the door in place.  

diamond jim wrote on 06/05/09 at 14:32:15:
I'm getting 52-55mpg with 55/stock/155.

I turned out the mixture screw to reduce afterfires, so I'm probably excessively rich at idle. I'll pull the plug tomorrow (first time taking the tank off).

My only main jet options right now are 145/155. I'll probably try no spacer and adjusting the idle mixture before I buy more jets. I don't want to make a hobby out of rejetting. No offense.  

Other than a "plug chop", is there a way for an inexperienced rider to judge the main jet?

Story:
I was talking to a coworker about my carburetor questions. He's a real car nut. Has a BMW he races. Does all the work himself. Anyway, I was asking his advice and he replied, "It's got a carburetor, be happy it runs."  

-D. Dwarf

BurnPgh wrote on 06/05/09 at 22:55:24:

I do have hills.

Today I intend on pulling the head cover and tightening the cylinder nuts, but if it doesn't rain tomorrow I'll give that a try.

-D. Dwarf

I have got my carb tuned about right I think...I am still getting the backfire only on the decel, but I have a straight pipe.  You guys think that adding some back preassure like a stock pipe would fix this?  No accel, decel problems, or shut down problems.  Just the backfire on decel, but response is good.

As far as I know (bike had a previous owner) the carb is running a 150 main with a 55 pilot jet no bleed holes.(This is what I was told)  And the screw is 2.25 out.(I confirmed the screw.)  Just trying to get the right tuning on the decel now.

Thanks,

John