carb questions

[Eddie Gravy]

i feel like I’m in vocational again, shop time during the day and studying the forums at night.

after getting my disassemble and reassemble times down, and hell, mounting my carbs used to take a heart attack and a head rush to get on, now nuthin.

ive searched but now i ask.

can get it to idle w/ choke full and half, lil throttle for closed choke to keep idle. with the choke closed i cannot rev rpms much past 2K with choke open as loud as i wanna go (7.3k). neighbors knew of a sleeping monster.

the choke or enrichening circuit is both fuel and air? yes

the butterflies have to be closed for the pilot screws to idle the bike? if so what could i be doing wrong? i do have a deceleration pop out of carb 4, intermittent though, n starting a backfire muffler pop on 3n4 side. those two are related

i've cleaned and cleaned and cleaned and for fun cleaned again. i want to keep the jets i have and possible raise or lower a clip on the needles.

79sf standard size jets across the board, pod filters, 2 - 4 no cross over exhaust

[RUSH]

Try adjusting the idle mixture screws 1 1/4 turns out from the fully seated position, then check the carb sync.

[tarzan]

The enricher feeds fuel,the air mixes with it in venturi .Are your floats set at the right height? Did you disassemble and clean all the circuits in the carbs?

[corey]

All of the above, but specifically the carb sync. Makes the biggest difference in the world. I try to sync the carbs with the RPMs as low as possible.. seems more accurate that way.

Seems like the biggest problem right now, especially with the intermitent pop out of cylinder 4.

[Eddie Gravy]

air fuel fire

bowl heights at the leanside 25m of the 24.7mm to 26.7mm book instructed. could play the median with 25.7.
will try 1 n 1/4 turn out on the idle screw, though 2,3,4,5 turns out seemed rough, maybe enrichner gives air needed not fuel. will turn it in.... can rev with the choke, but wont idle with out choke, throttle idle but nuthing over 2k.


ok. pop in carb out air main jet, what causes the pop with smoke/mist out the air side?? to lean to rich?
the constant clean clean and clean is well burned in to my head. im confedent with my many carb surgical procedures. will blow out number 4 again

am i drownding my carbs in air?

[81xsproject]

Okay, here is the thing with these carbs, if they are clean, functional (not physically broken), have proper equipment installed (as in not some jets from some mystery carb kit), and are within 3 jet sizes, they will run. They may not run great or smooth but they will typically work. Major performance issues are not typically needing to move the needle clip one down/up or the need to go up a size in the main or pilot or a half a turn of the idle screw or lower the floats 1mm. Now of course if some PO put the needles on the very top notch, eyeballed the float heights, installed some carb kits that belonged in a 650 (cuz they had them same look'n' carbs), screwed the idle mixture screws in so tight he stripped out the slots and smashed the needles tips, etc., etc., then they just don't run good if at all. Despite what some might say, I would say that these carbs are quite forgiving. You should however re-jet for those pods. There is days of reading on the subject.

Do you know that the rest of the bike is good to go? Does it have good compression on all cylinders? Have you repaired the pick-up coil wires yet (one of the most common problems on the machines)? Unfortunately carburetors should be the last place to look when trouble shooting and most peoples first choice when the times come.

[Eddie Gravy]

ah confidence in my carb abilities. yes fortnights of reading. will invest in main jets by two increments. but if starving from fuel from the bottom, setting the needle richer would compensate for smaller mains, pull the 'plunger out the hole'

also close to sea level in a desert climate, well not the past 3 days.

will check out compression and valves cause i dont know. do these things throw cam chains? ignition gear was in top order, pickups've done.

found a thread of a "Flatlander" that had same problems, it was cams not corresponding to a tdc. what would tdc stand for? total dead center marking in the picups

[DGXSER]

Tdc

Hey Eddie,

TDC = Top Dead Center. There is a T and a C mark. I'm going from memory here (dangerous at my age) but I believe you want the T mark for setting your chain, the C mark is for adjusting the cam chain.

Set the T mark, pull your valve cover and look at the cams near the gears for the marks. TRBig posted an excellent pic of this on a thread here somewhere.

Happy hunting and good luck with your efforts!

[TopCatGr58]

Okay Eddie,

Bike will REV to 7.5k WITH CHOKE/Enrichener pulled out, which provides much more fuel for the system, so that indicates LEAN when it's not able to pull past 2k WITHOUT it!

Secondly, no aspersions on your carb cleaning skills, but just some questions on technique. Did you soak entire carb bodies in cleaner? This can cause damage to butterfly shaft seals causing massive vacuum leaks=LEAN.

With bike running, use a Bic grill or candle lighter, hold the trigger down enough to release gas but NOT activate trigger, and wave around the shaft seals and carb intake mounts and vacuum port caps listening for changes in idle...should rev slightly=leak!

Did you remove the MAIN JET NOZZLE/NEEDLE emulsifier tube from the carb body by pulling it up thru the body where the vacuum slide fits? There are many fine aeration holes in the nozzle, but if clogged, will not function properly.

Did you inspect the vacuum slide diaphragms for pinholes, have you checked their ability to rise and stay up by lifting them all the way up, holding your finger over the arced upper port on the filter side of carb and see IF they stay up, or drop down very slowly, not just swoosh shut?

That's about it for now, keep at it!
T.C.

[Eddie Gravy]

found shredded pickup wires, the north pair had been repaired, now time for the south set to get attention. also, the vacuum assy has never been hooked to anything...where should the extra 12in of tube? it had just laid across the engine for 8k miles

cams line up.

diaphrams in carb are sealed no holes. no rev with external gasses

while i had it running today, a short portion of my shop time, i had a cold fourth header, gonna attribute this to the shredded pickup coils. though i had spark in all four plugs!!!?


man am i looking forward to 90

[bikerphil]

the vacuum assy has never been hooked to anything...where should the extra 12in of tube?

The hose from the vacuum advance hooks to the port on the #2 carb body (not on the carb boot). Look between carbs 1 and 2 and you should see it.

[Eddie Gravy]

the port that i have my octopus nipple on... and my octopussy nipple that has been wrong should go...?

[DiverRay]

the port that i have my octopus nipple on... and my octopussy nipple that has been wrong should go...?

To one of the capped ports on the INTAKE BOOT. I would also check ALL the caps if you still have the original thick cap with a clamp on it. They tend to leak, and cause idle/low speed problems.

[bikerphil]

Octy goes on the #2 carb boot.