Question for all..

[MindWebs]

How many times can you run with gas in your tranny?

before engine seizure that is..

i think i've done it 4 times now.

2 before carb rebuild, total miles = 85
2 after total miles = 55

the first 2 literaly had more gas then oil.
the second 2, 1/4 - 1/3 gas to oil ratio

i'm starting to become irritated.
to the point of wanting to sell the bike.

love the power and handling but dislike the fussy carbs.

oh, yeah i nuked the clutch on the 2nd gas wash if that tells you anything.

just wondering if i should walk away now or if these really are "bulletproof".

[MindWebs]

info

i'll supply the info so maybe someone will see what i missed..

correct float height, factory = 25.7mm
mine. = 26.2mm using the butt end of a digital calipher.

All jets are factory for the bike
as per Full rebuild kits from georgefix.

pilot screws are set to 4 turns out, sportster pipes.
i set this using a write-up i found on here.
stating to turn idle low (6-800rpm) and from 1&1/2 turn slowly richen mix until
you hear idle increase (that happened at 3 1/2 turns out) i added 1/2 turn to be on the rich side. this 11 has been running lean for a while.

i don't get it...
i've worked on LOTS of mukuni carbs and kehin carbs and i've never had this
level of problems before.

these carbs are clean. no question about that i've had them out 13 times now
in the last 3 months.

carbs are alway's synced upon re-instalation.

what did i miss?

thanks guys
webs

[Cobia]

Maybe...

How many times before irreversible damage is done? I don't know, but....
It is not uncommon for the floats to get hung up and stick on the gaskets and thus causing it to flood like yours.
When I do my carbs I grab them by each end of the rack and rotate them and listen for the floats moving, all of them.
Then when they're installed, and I'm priming them, I tap/rap the bowls with a screwdriver handle or ratcher handle to cause vibration and ensure they're free and operating properly. I works every time for me.
Don't give up, it's worth the hassle.
Good luck.

[TopCatGr58]

Hey there Web,

I haven't searched for your previous posts. Your profile just says 79SF, but doesn't have any info about any mods, or if you are totally stock, intake and exhausts?? So can't comment on your jetting without knowing this!?

Okay, you've rebuilt your carbs with known good parts, but you didn't say anything about inline filters? Also, the 79's use the solid metal type float needles. Jessie/81XSProject posted about a conversion to VITON/rubber tipped float needles for the early carbs to help reduce the leakage tendency. The floats can also hang on the carb body/float bowls, the bowl gaskets, and even on the float pins? Crud from the tank can wedge between the float needle and seat, causing it to leak!

Don't know how hard you ride, but running with that much gas/fuel in the oil, good chance of gauling the bearings even if you haven't spun them. I'm sure folks like Tod and DiverRay would say you should tear it down/split the cases to at least inspect the bearings.
T.C.

[psycoreefer]

Do you have the original brass floats or the newer style plastic floats? I switched out the brass ones for plastic and I had to trim about 1/16" off the end of the float furthest from the pivot because they would always hang up on the bowls.

[BigDick]

one more thing, it's the general consensus that the rubber style automotive fuel line is bad because the petcock will shave off little bits of rubber on each installation, also when they get older it's said they tend to get brittle and flake

[oseaghdha]

It ain't the carbs

It's your petcocks that are bad.
Sits all night, drip drip drip.

[WMarshy]

It's your petcocks that are bad.
Sits all night, drip drip drip.

I second that. My carbs leak a little when sitting but into the air box not down in the cylinder. I've gone through this problem before with gas goin into the oil. Not fun! Im considering going to the on/off style petcocks and ditch the vac operated ones. Anyone got a good source for them? I see PNM has them... dont know if their price seems reasonable..?

P.S. Its a good cheap idea to have inline filters!

[DGXSER]

I'll second the auto fuel line theory. I had no problems with leaking floats until I rebuilt my carbs. At the same time I eliminated the Octy on my special. I used auto fuel line, and had lots of issues with leaking float valves. I have since ditched the auto fuel lines and used the yellow fuel line made by Briggs and Stratton from Home Depot and have not yet had any leaking carbs since. (I just knocked on every wooden object around including my head!!)

[Larrym]

I'm siding with petcocks/automatic fuel shut off system here. If the floats were leaking enough gas to put that much fuel in your crankcase the performance of the engine would definitely tell you: bogging down or black smoke coming out the exhaust.

I've got a number of engines which use carbs: outboard motors, generators, my 79 special, and of course my truck. In all of the motors where the fuel is gravity feed (fuel tank positioned higher than the carbs...) I use the petcock to shut the fuel off. For my 79 Special I switched to aftermarket manual shut offs and use them every time. I have never relied on the float/needle valves to truly provide a "shut off".

Sure it's frustrating to deal with a fuel system that's "acting up". But then when you finally nail down the true problem and come up with a solution the frustration ends. (at least on that particular problem...)

You've got a 50/50 chance that the engine has enough mechanical damage now to (ahem...) Fail. At the same time you have the chance that this damage has not occurred. I'd say get a mechanic's stethoscope and listen to the engine bearings and lower end. Trust your ears. If it sounds like nuts/bolts bouncing around in a metal can then don't drive it.

[dbeardslee]

You may indeed have petcock issues, but I have to second what TC said about the viton tipped needles, and what psyco said about plastic floats. I changed out my brass floats for plastic, and changed out my fuel valves for XV920 viton valves (both the viton-tipped needles and the seats). I've got manual petcocks on Betsy and I can leave them in the 'on' position without getting any leakage. With those floats and valves you may not have to modify the tab on the floats. I've also got the black automotive fuel lines and have never had a problem with them coming apart, and I've had them on and off a lot, but YMMV. Then again, I've got inline filters, so maybe that's why I haven't had problems.

Are your brass floats pinched in on the sides, or are they still in the original shape?

[MindWebs]

hmm..

Lots of good suggestions here..

yes i'm using auto fuel line, still have the screens above the float valve seats

Stock air box.
the only "mod" i have is sporty mufflers.

bike is a 79 xs11 special.

I'll swap out the fuel lines for plastic and rebuild the petcocks.

i've allready removed the octy, that was part of my first 2 wash outs.
(i always turn my petcocks to off when not riding)

I'll start with these 2 repairs and try it again..

THANKS GENTS!!!!
Webs

[audijunky]

hope you get this worked out, these are great machines, hate to see you get rid of it