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She started! But she's angry!

  • Thread starter Thread starter J_C
  • Start date Start date
J

J_C

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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!
 
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?
 
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.
 
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 :)
 
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.
 
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!
 
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.
 
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.
 
OK... I do have the carb sticks so I'll give them a go when I return next week :)
 
t3rmin said:
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.
Click to expand...

Ditto. Bench sync is just to get it started so you can do a real vacuum sync. Also make sure you don't have any vacuum leaks. Did you put a plug over the vacuum nozzle on the #2 carb?
 
DimitriT said:
Ditto. Bench sync is just to get it started so you can do a real vacuum sync. Also make sure you don't have any vacuum leaks. Did you put a plug over the vacuum nozzle on the #2 carb?
Click to expand...

What do you mean by putting a plug over the vacuum nozzle? That's connected to my petcock right?


Another question... I mentioned the best RPM method... is there a specific order to performing that (ie carb 3 then 4 then 1 etc). Also, should that be performed before or after the synch? I'm concerned about it in general since most people talk about their air screws only being out 1 or 2 turns, and when I started doing it for #4 it went 3.5 turns out!
 
have you checked to see if your cams are in time?

might not even be it but sounds a bit suspicous
 
J_C said:
What do you mean by putting a plug over the vacuum nozzle? That's connected to my petcock right?
Click to expand...

This is something that gets me at least once whenever I start doing a sync. On the #2 carb body, there's a nozzle which you normally connect to a hose that goes to the petcock. You need to plug that up when you sync the carbs or all bets are off.
 
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