running to lean

[Jasonwallace99]

anyone have any clue what could be wrong. sorry for the long ass paragraph in advanced
I have a 2005 sj that's all stock, I recently put a brand new Ltd. factory b pipe and ada head with 37cc domes. my comp is 175/175.
I left my carbs settings at 70/130 with 1.5 needle and seats with 115. gram spring with both pop offs at 55 psi
I noticed on a 3 sec full throttle run my plugs were very white, so I was told to drop my pop of to 42 and jump up to a 135 main, my plugs were still white all the way to three turns out on the high speed so I chose to put in 75/140s just to play it safe, I ran it for about a couple mins from idle to half throttle and checked the plugs as they were wet and a copper color, I ended up doing a full throttle run and cut it off to check the plugs, it ran fantastic but they were dry, hot , and a tad bit lean so I turned my high speed adjustment out to three turns to see and I got the same results with the same exact power. at this point I got pissed and threw in 147.5 main jets and opened it to three turns just to see a black plug. I still got the same power and results as the 140
anybody have any idea? I cleaned my carbs twice and they have a fresh rebuild kit on them.

 

[fastgtfairlane]

if they are fresh plugs it could take some time to actually show color. besides, you cant technically do plug chops without a 10x magnifiying glass to really be able to read the plug. the best way to tune is with a tachometer. the colorless plugs could be a result of piston fuel wash which is a rich condition. if the engine accelerates smooth, with no hicups or bogs and hold steady on top, it sounds like youre dialed. when i was running dual 38s with the stock flame arrestor and 2 screens removed, i was running 75 pilots, 135 mains with 1.5n/s and 115g springs and mine ran great even when i took it to daytona in january. that was with a bpipe with c4 chamber. since moved to dual 44s

 

[Jasonwallace99]

if they are fresh plugs it could take some time to actually show color. besides, you cant technically do plug chops without a 10x magnifiying glass to really be able to read the plug. the best way to tune is with a tachometer. the colorless plugs could be a result of piston fuel wash which is a rich condition. if the engine accelerates smooth, with no hicups or bogs and hold steady on top, it sounds like youre dialed. when i was running dual 38s with the stock flame arrestor and 2 screens removed, i was running 75 pilots, 135 mains with 1.5n/s and 115g springs and mine ran great even when i took it to daytona in january. that was with a bpipe with c4 chamber. since moved to dual 44s

the only thing I'm not getting is why im not seeing any changes from the high speed adjustments or even changing the jets

 

[Harbor]

The low speed jet has a huge influence and is way more noticeable on changes to jet size...
High speed Jet not so much

 

[kevbo]

the only thing I'm not getting is why im not seeing any changes from the high speed adjustments or even changing the jets

The pipe requires a richer setting that the stock exhaust. Your sbn38s don't pull very hard on the main circuit so jetting will be much less sensitive than the pilot circuit. Since you are most likely on the rich side with 147 mains, start closing the top screws until it pulls hardest. If the screws bottom install a smaller main jet, open the screws and continue until it pulls hardest. At this point you have found the best power mixture setting. Any setting rich of this will reduce power, any setting leaner will increase combustion temps. Your plugs may be darker than expected and your main jets larger. Testing is ideally done on glass smooth water with a tachometer. I can often load the engine similarly by strapping the ski to an open trailer and sinking nearly up to the hood seal. This makes very quick work of jetting.