She started! But she's angry!

[J_C]

I got my gas tank back from paint so I hooked everything up. The bike had been completely disassembled 4 months ago and has been in varying degrees of being cleaned, repainted, etc.

Before I broke it down the #4 carb wasn't firing at idle and had tremendous popping. When I hit the button... 2 seconds later it was roaring, all four firing away. It sounded fine at first, but then there was an increasing amount of popping as the bike warmed up, and I even saw some flames come out the pipe with it popped/backfired. My #2 and #4 headers are now gold, with bits of blue creeping in. There was some white smoke creeping out of the exhaust pipe between the headers and the can and the area there where the two pieces meet now looks brown. Obviously something is very amiss.

I bench synched the carbs before putting them on. I suspect I'm going to hear this is a lean condition, which if it is the case, won't need any additional follow up yet as I'll be rejetting to Chef's leaner recommendation. But if someone know of another reason why please let me know. Thanks!

[J_C]

Errr. Edit above... I suspected that it would be due to a "richer" condition given the backfiring & flames coming from the pipe... but apparently the gold and blue are typical of a lean condition? Could anyone lend some advice?

[chef1366]

You didn't over oil your new K&Ns did you?

[J_C]

Err... what?

[rosco15]

Flame in the pipe is usually lean. A friend just built his race motor for his car. When we fired it up it was popping and there was flame in the pipe. We richened it up and got rid of the flame and popping.

[J_C]

Thanks Rosco! That confirms what I originally wrote (though not my original guess!) I'll need to do some more research to find out how to richen the mixture. I know they should all be jetted equally so if two are fine, I just need to get the others there as well

[wharrah]

Does anything change if you run with the choke on? might help u troubleshoot... quick and easy way to see if the popping and flames quit... just a thought.

[J_C]

Does anything change if you run with the choke on? might help u troubleshoot... quick and easy way to see if the popping and flames quit... just a thought.

Excellent point! I'll try that

[J_C]

I tried the choke and a few other things. First, I noticed that the popping seemed to be more in the 2k-3k range than at idle. Choke didn't seem to help much, maybe because it put the rpms in that range.

Then I tried to use the highest rpm method on the 4th carb. I noticed that I was about a full 3 or more turns out before it hit the highest RPM, and by that time the bike was popping again because it was up around 2.5k rpm.

Any more tips and tricks appreciated!

[chef1366]

Are you using the Mikuni 47.5 pilot jets?

[J_C]

Yeah, I'm pretty sure all I changed were the mains and jet needle

[J_C]

I just went outside and recorded some stuff. Looks like the bike won't accelerate past 5k rpm without like a second or two lag time before it jumps to 7 or 8. There's some popping in the audio too.

http://socal-letsride.com/storage/GS1100L/CIMG0148.WAV

[GS850_Coug]

Typically, if it runs crappy cold and gets better when warmed up, there is a lean condition. Rich condition usually runs worse when warm (which is why you start it with choke on--> making a rich condition-and take off choke when warm--> making a lean condition). Check this site for more carb tuning info. Best carb info I've been able to find, including info on individual circuit symptoms.

[chef1366]

Needle circuit is off for sure.

[t3rmin]

Do a real vacuum sync. Bench sync is worthless in my experience. Had a completely cold pipe after a bench sync that cleared up totally after a vacuum sync.