Need carb help... bigger jets?

Hello all. I'm a new owner of an 83 XJ750 Maxim. I bought it a year ago, went thru the whole bike, after a ton of reading and tinkering I got her running & looking good enough to put on the road. Long story short... I rejetted carbs after adding a K&N filter and after market exhaust. I set all the pilot screws to 2 and a half turns out to start. I've done several plug chops and made several small changes to the screws turning each only a quarter turn each time. I'm now at almost 4 turns out and plugs are still white. Bike used to backfire bad at 2.5 and 3 turns out... Now backfire has gone away so I know I'm closer but I'm still lean. What do u guys think? Bigger main jets? I've done a lot of reading and wrenching but not sure where to go from here. Please help!

 

does it look like this? this is good.

 

when you say plug chops are you actualy cutting the plugs to look at the base of the insulator?

 

here's good plugs, your looking for a thin even layer of carbon around the base, the part where the tang attaches before the threads. Most of the pictures you see were before they took lead out of gas and replaced it with corn syrup. I'd try one size up on the pilot and one up on the main.
check this out http://www.factorypro.com/tech/carbtun.html

 

When I say plug chops I mean riding the bike a few miles then getting to open road & hitting kill switch and coasting to a stop, letting bike cool then pulling plugs to inspect color. I was under the impression this was the only way to tell how the bike was running at cruising speed.

 

Now I'm a bit confused. Mine are pretty close to that but I thought I was running lean... Let me back up... I definitely was running lean because the backfires on deceleration were LOUD at only 2 turns on the pilot screw... Now I'm at almost 4 turns... The bike seems a little sluggish when taking off but runs smoother overall and no more backfiring. But I thought the insulator should be brown/tan... Like an old cardboard box color brown... White = Lean Black=Rich. Tan/brown is what I want to see. Anyone else agree??

I've only run 91 non-ethonal grade gasoline. There's only a few places in my town to get it but I make a point only to stop there as I was told the ethonal aka corn syrup your speaking of, breaks down into water and these old xjs don't like it!

 

Looks like this yes.... Thought this was lean... Different sources say different things. White insulator around electrode is okay? I thought I wanted to see brownish tan.

 

both sets of photos have the tan color the longer you run the plugs the more tan you will see


buy a color tune to set your mixture around 70 bucks then it is a visual setting to bunsen blue

 

You can get gas without corn but you can't get it with lead. Lead is what colors the insulators.

 

If lead is what colors the insulators then they will be white regardless of running lean or rich? So any other way to tell without buying color tune plug?

 

What about race gas? It's about 9bucks per gallon. Does it have lead in it?

 

you didn't read that link in the previous post did you ?
9$ a gallon it might have gold in it, i don't know. does it matter? AVgas at the airport might have lead, i don't know that either.
google "carburetor lean drop method"