Topic: White plugs

[nevernoluck]

Sorry no pics right now but I have an 80 650, all but the carb sync of the 3000 mile tuneup done, stock 4-4 exhaust, 90 mains and 35 slow jets, stock air filter no vacuum leaks, running lean with white plugs right? Do I sync carbs then check again or jet it first? What jets next? Ideas? Plugs are a champion something in the 12 number range, tomorrow morning I'll pull them and take pics

[Vincent P]

Easier to synch and adjust the air fuel mixtures first then test; if the issue persists, then I would go with the jetting and a repeat of the synch and idle.

[nevernoluck]

Oh and the pilot screws I believe are 1 1/2 turns out, I know it only affects idle just trying to give all the info I can.

I was thinking of syncing first too, other than that there is no adjustments besides changing jets or pilot position on these carbs

[Vincent P]

Unless you have been messing around with the jetting originally, then I think its just a matter of synchronization to get some of the leanness out of them and get a bit more fuel going in.

[nevernoluck]

Unless you have been messing around with the jetting originally, then I think its just a matter of synchronization to get some of the leanness out of them and get a bit more fuel going in.

I haven't done any rejetting and I believe these are the stock jet sizes, I was hoping to hear that

[cheftuskey121]

pretty much posted with the same concerns just now! funny how that works! hope you get it resolved

[scunny]

don't think a carb sync will do anything for a lean running motor.
first cab off the rank put some NGK8ea or their equilivent and then see whats happening. your main jet sounds about right but I haven't access to my manuals at the mo.

[Vincent P]

don't think a carb sync will do anything for a lean running motor.
first cab off the rank put some NGK8ea or their equilivent and then see whats happening. your main jet sounds about right but I haven't access to my manuals at the mo.

Use these exact plugs and they are the best.

[InTheStreet]

Oh and the pilot screws I believe are 1 1/2 turns out, I know it only affects idle just trying to give all the info I can.

What makes you think that your lean problem isn't only on the idle circuit?  Are you doing plug chops at various RPM or are you riding, pulling up at or near an idle and shutting it off?  If the latter, you could just be reading your idle mixture, in which case you just need to richen up your idle screws. 

You should get the NGK's.

[curemode2002]

+1 on the NGK's these bikes don't take kindly to american plugs  (trust me on this one). With my 650 she always runs lean at idle even warm they are supposed to that's why the air adjust screws are capped  (dang EPA thing). You can actually adjust needle hieght in these carbs with small washers but I would change plugs, sync and set the air screws before you get to crazy. Jets for this model can be easily had at Z1 Enterprises or Siriusconinc for pretty decent prices and you can usually get a couple sets for tinkering.

[nevernoluck]

I will put the ngk in tomorrow and do some testing, they are sitting in the closet might as well use them, got the carb sync done and seems to cruise better but had the girlfriend on the back so was taking it easy, might have the cruising surge about taken care of

[grcamna2]

I've noticed the accelerator pump system on the CB650's are REAL easy to get clogged up & if they aren't All squirting nice & evenly in each carb. it'll give you a lean running condition.The tank gets "rust dust" in it and the accel. pump spigots in ea. carb. throat seem to be the first thing to clog up...along w/ the accel. diaphram having it's own issues.
They are a pain to clean out(it requires removing the rack of carbs),but once they're clean it'll run Great !

[nevernoluck]

Not so white?

[Vincent P]

Looks like normal wear to me. I wouldn't worry.

[curemode2002]

+1 I don't see the white chalky looking buildup I saw when mine was lean. Those plugs look just right.