rebuilt carbs - tune & sync

[dex3703]

Hi,

I have rebuilt carbs back on the bike but am hazy about everything that needs to be done to get it finally fixed up. The bike starts and runs but will idle low and eventually stall out.

Do I need to do that fuel level check thing in the Haynes book?

How do you get the mix right, since the pilot screws were replaced?

And should I get a manometer or can I use a vacuum gauge? Which is better/cheaper?

Thanks,
Derek

[Lucky]

82 carbs?
installing them and having them run right off is very good work! be proud of yourself!
--first, idle should be set to 1300 +/-50 rpm
--Second, Synq the carbs. Mercury manometer is the best $40 you'll ever spend, second choice is the yardstick manometer posted recently on here, also on my "ART" page. vaccume guage set up on my carb page is a poor third choice, and i'm going to delete that info one of those days.
--third, set the pilot screws in & out for best idle, then 1/8 turn out (you may not notice a differance, but your bike will)
last, test ride the bike, if you have a flat spot adjust pilot screws in 1/4 turn to eliminate the lag. then go back & recheck the synq AGAIN.
--Lucky

[dex3703]

Yeah, I was pretty happy that it started. I was surprised, actually!

So you sync before you adjust the pilots? Thanks for the tip.

How do you adjust the pilots? Just turn them until you get the best running? Somebody here talked about using a CO meter, but I have no idea where you'd get one. I think they built one from a Heathkit.

Any suggestions on where to get a manometer?

Is that fuel level test in the Haynes book necessary?

Thanks,
Derek

[Blake]

To sync them the standard way..basically you turn in one of the two carb screws with the idle at 1,300 area for idle, until the bike starts to stutter (too lean on that cylinder) then turn out 1/2 turn.  and do the same on the other cylinder.

as for the CO meter... that would be me with the AFR meter that measures the remaining O2 in the exhaust..but unless your going to be doing some SERIOUS tuning, the hundreds of dollars for the meter is far from being worth it.  i orderd it because of all the mods im trying to do to the bike (k&n's..mikuni flatslides later), and also turning on my fathers suzuki intruder 1500 (his jet kit still leaves him with a big stumble with his k&n's) and also jetting my cadillac.  but at around 200-300 bucks to have someone properly jet your bike using a afr meter and a dyno,  within a couple of jettings the machine has paid for itself for me..


but with the turn in till stumble..then turn out 1/2 turn..that'll work good for you

[h2olawyer]

Derek -

You can build a manometer for $10 or less.  For a diagram, check here: http://www.xz550.com/art.html.  It is what I use and it works great.  You can get a manometer from most online motorcycle parts dealers - Dennis Kirk, JC Whitney, Shadetree Powersports, etc.  Those all use mercury which requires a bit more care than the ATF in the homemade one.

The fuel level test is not really necessary but can be useful to double check the float settings to make sure they are correct.  Shouldn't be a problem if you didn't bend anything getting the floats off for dipping.

H2O

[dex3703]

Thanks for the suggestions. Bent Bike has a 4 cyl manometer for $25, so I'll just do that.

I'll let you know how it turns out. Hopefully can get it all fixed up this weekend, along with other selling-the-house crap.

Derek

[tryder]

So you need to use ATF in the homebuilt manometer? Gear or motor oil won't work?

[h2olawyer]

Light wt. oil should be OK.  The red ATF makes it tons easier to see, though.

H2O

[Jon]

I found ATF too be a bit light for syncing the carbs... try a heavier motor oil or gear oil and it won't bubble around as much in the tube.