Fuel rail leak

[Mopaw]

I pulled the tank and air box to better analyze the the problem. All areas were dry. put a little fuel in the line through a funnel, and saw leaks appear along the fuel rail between carbs 1-3-5 and 4-6. I had the carbs completely redone two years ago, wasn't expecting trouble this soon. Anyway, going to pull the carbs and put new seals in the fuel rail. any suggestions on where to find parts? Thanks.

[The emperor has no clothes]

https://redeye.ecrater.com/p/39573511/fuel-rail-tee-kit-single

[RP#62]

You might as well rebuild the carbs while you have them out, you're going to have to split them all apart to replace the rail seals anyway.  Just did this on one of mine.

-RP

[98valk]

I pulled the tank and air box to better analyze the the problem. All areas were dry. put a little fuel in the line through a funnel, and saw leaks appear along the fuel rail between carbs 1-3-5 and 4-6. I had the carbs completely redone two years ago, wasn't expecting trouble this soon. Anyway, going to pull the carbs and put new seals in the fuel rail. any suggestions on where to find parts? Thanks.

just tighten the end nuts of the threaded rods that holds the carbs together. two rods per carb bank  those nuts do come loose over time. usually only 1/32 to 1/16 turn needed.

tap the carbs towards the T fitting using a wooden dowel against the carb bodies. usually only 2 turn tightened procedures are needed.

[Mopaw]

I tried tightening the nuts. simple fixes are often the best, but didn't work this time.

[98valk]

I tried tightening the nuts. simple fixes are often the best, but didn't work this time.

Since u stated they are new o-rings two yrs ago,
all I can tell u is that the OEM o-rings are Buna-N aka Nitrile, they don't just wear out or decay being in an enclosed environment. Same goes for Red-eyes, Viton o-rings.

tap the carb bodies and usually have to put some force on the nut/s. many times it will make the metal crack sound, and then it is tight enough.
in 75k miles I've had to do it twice, then zero leakage for 10ks of miles.
I know the higher grade of Buna-N of the OEM orings sometimes don't expand and contract with major temp changes sometimes, and that is the only time mine leaked. after the tightening procedure then zero leaks for yrs and I ride 30F to 100F.
good luck.

[Racernick]

I bought all my o rings from o rings and more sizing you need are
Fuel rail:   1.9mm x 7.8mm  Viton
https://www.oringsandmore.com/fkm-o-ring-7-8-x-1-9mm-jis-p8-minimum-10-pcs/
Vapor rail:   1.5mm x 6.0 mm  Viton
https://www.oringsandmore.com/fkm-o-ring-6-x-1-5mm-minimum-10-pcs/

[98valk]

if one looks up the ingredients of seafoam one would see that OEM Buna-N o-rings don't really care for those chemicals.

2=Fair (usually OK for a static seal)
https://www.rocketseals.com/chemical-compatibilities/

Seafoam, per the current MSDS, is 40-60% Pale Oil (CAS 64742-54-7), 25-35% Naphtha, and 10-20% Isopropyl Alcohol "IPA".
https://bobistheoilguy.com/forums/threads/significance-of-pale-oil-in-seafoam.175231/

Viton o-rings are good down to 5 degrees F, buna-n is good to sub-zero meaning it doesn't change size however, the aluminum fuel tubes do change size.

the threaded thru rods that hold the carbs together and change size due to temps and the end nuts can and do get loose.
first time mine leaked was due to loose rod nuts. tightened them didn't leak for over 40k miles. very minor leaked one bank beginning of spring when there was a major temp change over night.
tapped the carb bank towards the fill "T" took maybe a 1/32 turn on the nuts and hasn't leaked since.
and if one does more research Buna-N does not shrink and swell in gasoline. depending on the Buna-N formula Honda used there could be more cold shrinkage for better chemical resistance. I'm sure honda used the best ratio.

great info here
https://www.manuf-rubber.com/news/buna-vs-viton-seals-whats-the-difference/

[Mopaw]

THANK YOU Racenick! Your lead on the Orings was just what I needed. Tried to get them from Redeye, but they are not listed on his website, and no responce to my email. got everything back in place, no leaks, back on the road. Yahoo!

[Racernick]

THANK YOU Racenick! Your lead on the Orings was just what I needed. Tried to get them from Redeye, but they are not listed on his website, and no responce to my email. got everything back in place, no leaks, back on the road. Yahoo!

glad i could help other had given me this info so happy to share