Possible solution for the aluminum carb washer problem

[vl5150]

On those 10mm nuts that house the main jets, I've been playing around with different O-rings.  My rear carb tends to drain through the aluminum washer on the read carb and makes starting on one cylinder a pain while the fuel pump has to re-fill the float bowl.  Plus it leaves brown residue on my pretty Vision. ;)

So as a initial test, I tried a 6mm green oring left over from my A/C system rebuild.  There's mixed results using those with fuel, but it did seal it.  The 6mm is a bit too big and would squish out if tightened too much but it was a start.

So I remembered Harbor Freight carries a Viton O ring set.  I picked up the one below and I decided on the 5.25x1.78mm oring for starters.  It fits the threads sung and does not deform much.  I torqued it down "hand tight, then a little more" to not bungle the o-ring and so far so good.  I'll report any leaks and continue to test, but I think I have a winner.
The kit is about $10 and you'll have Orings for life.  Also the 20% off coupons are easy to get so really $8 so you can't go wrong.

[vl5150]

Forgot the link:
http://www.harborfreight.com/180-piece-viton-o-ring-kit-67525.html

[vl5150]

Pic added of the box with O-ring sizes.

[The Prophet of Doom]

Replace the Alu washers with copper ones and you will be golden - they are available in any auto or engineering hardware store.   


O-rings are the dead wrong thing for this purpose.  They tend to buckle up and get forced out of the joint and go all leaky. 
Crush washers would work, but I doubt you can get crush washers this size 

[vl5150]

I've seen the vitons used in case through engine bolts to seal out oil so I figure it should work for the carb jet bolts.  I removed the bolt today and the oring was not deformed and looked like new.  I just put it back on and re-tightned the bolt. The carb was still full of fuel and the way it was it would have drained out already.  I did pick up some copper washers and will eventually use them though.

[fret not]

Those sealing washers become work hardened with use, so every couple ot times you remove them you should anneal them.  Just a propane torch or gas stove will do, and just get them dull red hot and drop them in water, and they will be good to go.

[The Prophet of Doom]

Fret, I presume you mean the copper ones.  Alu washers don't go red, they just melt :angel:

[fret not]

Yeah, you're right.  The trick to anneal aluminum is to soot it well, like with a candle or acetylene torch, and then heat it until the soot disappears. A bit too much heat and you get a blob.

[vl5150]

Well I tried to find copper washers in the correct and I failed locally.  I did find a washer set at the auto parts store that's designed for Holley carbs for a similar brass fitting that covers the jets.

I used a flashlight and saw a nick in the carb body where the washer went so I carefully sanded it down with 1000 grit sandpaper. So no more leaks for the first time!

So I still think the Vitons will work in a pinch and the brass plugs are hand tight and then some so the washer doesn't break, but copper or new washers are the way to go.

[vl5150]

Well bad news, my leaky carb still leaks from the rear jet plug with the washer.  It's just slower and it's empty after a week.  I notice when I get a single cylinder running the engine until the rear carb gets fuel and comes online after 15 seconds or so.
My next test is using the washer with the viton o ring.  The washer will allow the O ring to slide freely as it's tightened.  I did this last night and will see if I get another leakdown on the carb.

[admin]

just an observation.  you might be over thinking it here.
pick up a piece of fine sand paper, run it over both sides of the washer.
if you can do it on a piece of glass, even better.
the aluminum washers are really the way to go on this.
make sure you use extra fine and maybe hit the carb body around the area
if it doesn't look smooth.

-R

[vl5150]

Just as a follow up...

I did try to sand the carb body and washers lightly.  I went with the viton o ring and a washer.  No leaks in 3+ mos and a non issue at this point.

[Rikugun]

My first reaction to O-rings was much like POD's. With a metallic washer the screw can be tightened until the parts all contact and then snugged until adequate resistance indicates it's "tight enough". How does the O-ring give that kind of feedback? Too tight and the O-ring deforms, too loose and I'd fear eventual loosening on it's own. How do you get to that "Goldilocks" just right tension?  :)

In the engine case bolt scenario you described, are there machined grooves for the O-ring to nest in?

[Blake]

You can get the aluminum washers from mcmaster.com.   Get the aluminum washers, mark it up with a sharpie, then propane torch it on the opposite side until the sharpie disappears.  You now created annealed (super soft) sealing washers.   I dont remember the exact size but i bought a 50 pack of them for about $9 a while back.

[vl5150]

I tried the aluminum washers many times with the same result.  A drain down on the rear cylinder.  I must have a nick there that the sandpaper didn't get out.  With the washer and O ring, the Oring is protected by the washer and the washer slides a bit thus protecting the O-ring.  So it's been many many months here and no issues so I've moved on from this and on to more solutions.  I don't have torque values but snug is fine.

I picked up a Buell Cyclone a few months ago and when I did the maintenance on it I chuckled when the case covers were using the same concept. 

[Walt_M.]

A solution that works is a good solution.

[Rikugun]

Why would case screws need sealing washers and )-rings? Then I saw the Genuine Harley-Davidson Parts logo on the bag.

Just kidding Harley, we love you.  ;)