New member with a big leak.
KTRT:
Yes. Wasn’t there.
KTRT:
So, update.
I removed the carbs.
If someone know the trick for that plastic firewall, I’d like to know because that was without irony the hardest part.
I removed the bowl. They looked mostly clean, but upon closer inspection, there’s a white powder like deposit.
The float needles. Two of them had a sticky light orange deposit (varnish?)
I can already tell it’s been opened in the past, but I don’t think it’s been done particularly well since I can find dried bits of o rings and whatnot.
Mooskee:
Quote from: KTRT on August 24, 2025, 09:27:04 AM
So, update.
I removed the carbs.
If someone know the trick for that plastic firewall, I’d like to know because that was without irony the hardest part.
I removed the bowl. They looked mostly clean, but upon closer inspection, there’s a white powder like deposit.
The float needles. Two of them had a sticky light orange deposit (varnish?)
I can already tell it’s been opened in the past, but I don’t think it’s been done particularly well since I can find dried bits of o rings and whatnot.
The Plastic air dam: The manual says to "Remove the rear upper engine mounting bolts, bracket bolts
and engine mounting brackets." They wont move far, but if you dislodge them and move them back a bit, you will get clearance for removal and installation of the carb bank past the plastic air dam.
If that is not quite enough, take the choke crossover cable loose on the right side. Remove the bank by lifting the right-side front up (#1) and the left side back down (#6).
The manual also says to remove the #1/2 coil out of the way. I never do. I seem to be able to get them out without messing with the coil.
Float needle deposit.:
Sounds like the ethanol fuel is breaking down and starting to leave deposits. You might get away with cleaning her up a bit. Whatever you do, do not spray carb cleaner into the carbs. It may very well attack the rubber in the Air Cut Valves, and the CV diaphragms, both very expensive components.
ALSO, do not blow compressed air into the carbs with the ACVs or CV diaphragms attached.
I can't see what you are looking at. However, I have seen many carb sets where ethanol fuel is in various stages of breaking down. Your description sounds like it is in the early stages and may be recoverable without a complete tear down.
Pull the jets and look through them to make sure they are open. If you have access to an ultrasonic cleaner, clean them or replace them if they are clogged.
Since you indicated there is a possibility of the float bowl needle valves sticking, personally I would replace the float bowl needle valves with K&L 18-8955 K3 needles. At the very least clean the ones you have. Make sure the floats are sitting at the proper height by turning the carbs upside down. The floats should sit with the little raised circular mark centered right on the edge of the bowl. There is a measurement, but that is where it ends up. If the FBNVs springs have weakened, the floats will sit too low. Very common after so many years. The weakened spring and possibly worn tip on the FBNV will cause the fuel in the bowl to be too high. and possibly allow the FBNV to let fuel in when it should close.
I am trying to give you steps to recover without rebuilding.
IF you determine that the fuel leak is on the fuel rail from the tees or tubes. Try tightening the nuts on the connecting rods (7 ft lbs. torque). If you still have a leak you will have to break apart the carbs to replace the fuel rail O-rings. At that point you might as well rebuild them.
I do it all the time, so it is easy for me, but the manual has good instructions. If you are a decent mechanic, you can do it. Just take your time and pay attention to detail. The biggest part of it is doing the same thing 6 times. An ultrasonic cleaner will certainly help. If you decide to do it, I can send you my inspection checklist, as well as other info.
Balancing:
You will need to balance the carbs if you take them apart. The tolerance is 1.6 in mercury. #3 is fixed and the other 5 are balanced to it. You will need a good set of gauges, or ideally a Digi Sync.
Tuning:
Tuning is more forgiving than balancing. Balancing must be done first. Then tuning. You can get away with setting the pilot screws to the starting point in the manual. It won't be perfect, but it will be in the ball park.
Here is a link to my Youtube channel with a video of me describing balancing and tuning on my test engine.
https://youtu.be/LrbXjakM-TI?si=MkCH2H77Ej4W71yy
KTRT:
Thank for all your advices. I will try all that later today.
I was thinking of simply pouring fuel down the hoses (with the carbs closed, of course) to see it the leak comes from the fuel rail. Sounds good?
Ah, I forgot. While removing the drain screws, I noticed only a few still had a pointy clean tip. The other look corroded, covered in brown hard stuff (rust from water sitting down?), so I guess those will need replacing.
KTRT:
Found the leak.
The T shaped plastic piece on the left bank, between carb between carb 4 and 6 if I’m not mistaken
Yup, so it was definitely the o-rings. They were so dry they all snapped in two when I wanted to remove them.
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