Pulled of my Exhaust... Three black tubes and One WHITE!!!

1980 XJ 650 Maxim, 23k miles, aftermarket exhaust dual 2into1 (PO), factory air box...
I know a little about engines in general. I know its running lean, but after reading a bunch of the forums I'm not sure if I want to adjust anything on this carb at all. So many horror stories.
My XJ is a daily driver and runs great and strong. Sputters when she is cold around 3 1/2 to 4k rpm and occasionally pops when I down shift (hot or cold) only on the white pipe side. Should I just go for it and adjust that carb or should I find a XJ expert and pay the big bucks?

 

What you need to do FIRST AND FOREMOST is get your VALVES IN SPEC. The XJ will run "great and strong" right up until you burn a valve or hole a piston.

THEN you need to check your float levels, and probably service the carbs.

But you cannot effectively adjust the carbs until the valve clearances are in spec.

Popping is generally a sign of a lean condition; and you really should fix this before you damage the motor (if it's not already too late.)

Get the valves in spec and run a compression test asap. Then get after the carbs. Your motor is right at the "danger mileage" if the valves have never been touched.

 

Ok spent most of Irene reading your write ups and posts... Going to order the tool and gasket asap... However IF (big if) the valves ARE in spec, should I replace them just because. Some say replace them as if they are brake pads... I ride this bike hard... I did three laps around Pocono Raceway. Hit 116MPH on the stait and just under 100MPH on the corners. I ride my XJ every chance I get...

 

I certainly wouldn't pull the head and do a valve job "just because."

Get the valve clearances in spec; then run a compression test.

Then, based on what you find during those two processes, decide on the next step.

 

Ok, thanks for your help! We'll see what happens...

 

That's "Racer's Mentality"

In a world where 35-hundredths of a second determines whether you get positioned on the Pole or the outside of row five, ... you might have the Crew remove the Head and swap-it-out for another one, ... if you thought you could gain two horse power.

Do a Compression Check it see if that White Hole is OK.

If it is,... take corrective action to get the Mixture right.

(When you get the White Hole closer to where it belongs by adding Fuel or correcting an Air Leak, ... you're Lap Times will be slower.)

 

I don't race. just had an chance to run the track (not open to the public) so I jumped on it, and got on it. Fastest my XJ has ever gone I'm sure...

Going to start taking her apart tonight. sad day. A friend of mine (with a broken leg) is letting me ride his 08' R6 while the my XJ is down...

 

DON'T JUST take it apart. You need to diagnose FIRST. You can't run a compression test if you pull the head.

Get the valve clearances in spec and then do a compression test. THEN pull apart if necessary.

 

oh no...Just the tank and valve cover is coming off tonight. (to get clearances) then she will sit untill I get the new shimms and gaskets. (if needed)

 

If you were able to push that Bike within 10 mph of its known Top-end; I doubt there's anything major that needs to be done.

But, I understand the obsession with wanting peak performance. Back in the late 70's I raced an MBG. Used to all day Friday and Saturday doing stuff that didn't need doing just to be sure it was done and checked-off in time for Sunday.