She Runs, But sputtering se-fla

[Viking500usa]

Hi Everyone, the #48-5019 "set" from mikesXS is wrong size float seat. the needle is ok (a lil sharper point but good fit), but the seat just falls into the hole that has the threads for the screw in float seat. I had also reamed a drill bit backwards to get a clean edge on the old ones. works out to no more leaks. runs but now needs tuned. Word to the wize, if you see a ring with the magnifying glass, try to go with new. or polish.
Goin over to see Jazzrat tomorrow, maybe if I can tune it to ride down there, but we're just getting our worst cold spell of the year in Florida, with low 30's degrees with the wind chill. maybe in the 40-50's daytime high,
Im goin to try to tune it b4 I install new exhaust, but its awfull tempting.
Thanks Everybody !
Don 79sf

[Viking500usa]

Hi Everyone,
I installed the the new float needles as you all have read from one of the previous posts, float travel not too far to pinch the needle cock-eyed. but this has not fixed my problem of fuel coming out of the airbox when running and when off. (carbs #2 & 4) have to stop it by turning petcocks to off. took it for a quick ride round the block, but no change. I'm tempted to drill out the brass inserts for the vacuum vents on the airbox, but am paranoid. =) dont want to add to any problems
Also tempted to pay shipping and pay to have someone from this list tune it for me. someone who really knows what there doing. Neither Jazzrat (a couple towns over) nor I have found a shop that wont screw you one way or the other. Only the owners will steer you right.
Any suggestions?

[GNEPIG]

.. do you have a pickup truck, a van or a trailer? or have a freind or relative that will lend you one?. if you dont have one of these perhaps you can rent one.. if you drag it over here one sunday i will have a look at it.. i live about 200 miles away.. pm me if interested
Gene

[jazzrat2000]

maybe we can rent a big truck and bring mine too!

[GNEPIG]

.. yeah, what the hey, this could be fun.. the more the merrier

[Viking500usa]

hey gnepig, 200 miles one way maybe too long for a day trip.

I connected the fuel tank to carb on the bench today. fuel leaks when on prime. On the backside of the carb (right side up) there are 4 holes. theres a vent hole at the 4 o'clock position. opposite side from the air pilot jet. this is where fuel leaks out on #2 and 4 when on prime. Adjusted the leaky ones to 26mm, made sure the floats travel well inside the bowl, its ok.
reassemble, retest, leaks at same hole. what gives? whats that hole for?
anybody know where or have a carb fuel flow diagram (lost mine).
Is it a good idea to depress the float spring slightly when measuring float height ?
Permethius knows quite a bit bout this, I keep re-reading his posts to try to figure this out.

Almost there,
Don 79sf

[GNEPIG]

yep, permethius is the man
no pressure on the floats when measureing
.. keep trying you'll get it

[Ken Talbot]

Don, has anybody asked you yet how the fuel lines are connected to your carbs? You have early-model carbs and there are two "T"s between each pair of carbs (i.e. between 1-2, and between 3-4) Your fuel lines must be connected to the lower T between each pair. The upper T is a vent connection. How are yours connected?

[Viking500usa]

hi Ken, I have the new yellowish/clear fuel tubing lines going to the lower T's. I had to replace my T's with the pricey brass ones with o-rings from the carb company. they were a very snug fit !
For the air vent hose (upper T) I used thick wall vac. tubing so not to kink easy. rebuilt petcocks & vac diaphram.
Im gonna try tomorrow turning carbs upside down to test float seats with fuel connected. we'll see the results.... if they leak, thera no good... thanks for the input, Ken. I keep asking myself what am I missing =)
Don79sf

[prometheus578]

"Insert comment here"

No need to drill out the brass "inserts" in the airbox. Just run a wire through them if you think that they're obstructed. The brass inserts meter the amount of vacuum from the airbox that affects the atmosphere in the float bowls.

On the backside of the carb (right side up) there are 4 holes. theres a vent hole at the 4 o'clock position. opposite side from the air pilot jet. this is where fuel leaks out on #2 and 4 when on prime

Ok, I'm confused. The early carbs, BS34-II have three holes and an upper tee for the vent. Later carbs,BS34-III, have four holes and no tee vent. Your post says you have a '79SF... should be three holed with a vent tee, but you say you have four holes and a vent tee.
Be that as it may.... one of those lower holes, as you stated, is for the pilot air jet, the other is for the main air jet. If one or the other leaks, yes, there's a prob.
Though it's been recommended, I've never run a drill bit backwards to smooth out a fuel seat. I cannot cast aspersions on something that I haven't tried, so I shant. The seat area must be pefectly smooth in order for the needle to seat and seal properly. I recommend using a Q tip and chrome polish. If that doesn't clean them up, then they may have a small nick on the sealing surface and must be tossed. The polishing with the Q tip will also ensure that the walls of the seat are smooth and free from gummy residue so that the needles don't stick.
Always bench test carbs before putting them back on the bike. Upside-down with the bowls off. Connect the fuel, and "BLIP" each float till fuel flows to it, then dry it off by compressed air (or if you're a "blow-hard" like me, use your lips and a straw!) Watch for where the fuel leaks from. Should be from the needles of carbs #2 and #4, but may be from all, #2 and #4 being the worst.
Of course, this is not a perfect universe. Once you've gotten it to the point were they don't leak upside down, put the bowls back on, flip it right-side up, and see if they still don't overflow. I suspect that you're gonna need new needles and seats again. I say needles again, 'cause I believe you stated that you received the wrong seats (along with matching needles), and many times the wrong needles won't work with the right seats.

[Viking500usa]

Thanks Prometheus, I needed to be corrected. I had no Idea which carbs I had. I've tried to keep everything stock, except new aftermarket exhaust, on the backside of the carb, there are 3 holes and an oblong one thats at the top. I just looked at some on ebay and those have the four hole style. which is not like mine, so, sounds like they're BS34 II's.
I'm glad I was paranoid, those vent holes I thought were a precise metering.
The float needles seemed an exact fit. even matched up side by side with the old ones. just the screw in seats were wrong diameter. any idea where I can buy the correct ones? I got the last ones from mikes xs. #48-5019 which I reread is for BS38's. Im going to buy the 48-1429 , they look a lil bigger on mikexs website, not too much to lose if I find the right ones. perhaps you might know of another source?
thanks,
Don 79 sf

[prometheus578]

"Please be seated"

I'll check the catalogs at work tomorrow.

[Viking500usa]

Hi. Ive tested the carbs updside down, used 2 old float seats that work good. tested,no leaks. reassemble carb bank, turn right side up, turn tank to prime, and gas starts streaming from the 4 o'clock vent hole on the backside of the carb. (#2 & 4)

Im stumped ! what have I missed???

so when the float bowl fills up , its over flowing out of the vent.
hmmmm, still stumped.
HHHEELLLLPPPP !
Don 79sf

[prometheus578]

"Time for the ol' Switcheroo"

Swap the needle,seats and floats from carbs #2 and #4 with the ones from #1 and #3. See what happens. A common mistake when bench testing carbs for leaks is that the individual does not "prime" the fuel line. They hook up the line, turn on the fuel, see no leaks, and think they're done. Unless you "Blip" the floats to bring fuel to the carbs, the line is full of air. Carbs appear to be non-leakers... though the trapped air is passing through the needle and seat as the line fills... and people think the carbs are good ..before letting the fuel get to them. Did you check the floats for fuel inside of them?(holes)

turn tank to prime,

I know.. dumb question... but did you turn the tank to prime when checking, and not to ON?

[Viking500usa]

Hi again, yeah I did prime the fuel lines, I lifted the needle on all 4 and some fuel trickled out from each, so they're primed =) I then blew them off with comp. air to dry. Im sure Im using "prime" , not "on". I havent checked the floats for holes yet. these carbs are streaming fuel b4 it has the chance to fill the floats (if they did have holes) but I shall do it none the less. would the float not sealing cause the fuel to pour out the vent hole? fuel streams out 2 seconds from when I turn on prime.
Confused...

thanks for all your help !
Don 79sf