Let's Figure This Out

[Coyote]

These are various photos of the carbs that came with my current 76' GT550. I have since replaced these with another set. I stole the set I am using off eBay for $100. You may remember messing with the melted carb bellows. Other than that, the hundred dollar set turned out to be in perfect condition. Those are now on the bike.
Even though it was decided these would work, I just couldn't bring myself to use them. It never was determined what could possibly cause this erosion. All three carbs suffered from this and I believe all three are shown. Other than these nasty jet towers, the carbs were fine throughout. There was no other corrosion / erosion anywhere else on these carbs, Just here. Not that important now, but I'm still looking theories on the cause. The only thing I can figure is some clown removed the main jets with channel locks or similar and grabbed part of the tower in the process. But that is a million to one chance - especially 3 times. SOOOooooo, what do you guys think?

[tz375]

That looks like water in the bowl - acidic water probably.

Or else they soaked the carbs in something corrosive

[Coyote]

I sincerely doubt it was caused by water. Here is a severely water damaged carb from my junk pile. The jet tower is intact. Must have been alumamites.

[tz375]

I have lots of white ones and a couple of them eaten by zinc moths like yours.

[GT750Battleship]

Maybe exposed to Methonal as used in racing fuel,I have a mate that races 250/350 Classic Hondas,& the first job after a meeting is to drain & flush the carbs to prevent damage like this occurring,due to the corrosive property's of the fuel
Cheers,
Roger

[tz375]

Not so much. I raced my Honda with Methanol for years and you are right that it has to be drained, but because it absorbs water and rots seals. It doesn't usually rot carb bodies. Ethanol is similar and is also a strong solvent but not likely to dissolve Mazak or Zamak or whatever they call that pot metal they made production carbs out of and depending on which side of the pond you are from.

Evidently there was a condition known as zinc pest that caused problems years ago which was really just impurities in the alloy.

Maybe the zinc pest has risen from its slumber and has started attacking old bike parts.....

[Vintageman]

looks like water to me as well... not as filled as the white one that must at times a had stream running into it In my part of the planet those fractures/chips may be from water freezing.

[pearljam724]

That is very odd. I would have to agree, I believe that was human inflicted. A clown, lol ! I'd have a hard time believing it was gas. Ethanol, race gas, etc. As you stated, that also explains why it was only the ends of the jet towers. Race gas would only eat at rubber or plastic parts, like Richard mentioned. Believe, this or not. I left a full tank of ethanol laced gas in a mower and trimmer for nearly five years without treatment, etc. I removed them both from storage to sell this spring. The trimmer fired up first pull and the mower 2 or 3. Left ethanol in my plastic oil tank for 2 days though and it was trash. Zinc moths, lol ! What the hell is that ? Lol ! Moths that lay zinc corrosion ?

[GT750Battleship]

Hi,plenty of reading on the Net,menthonal destroys aluminium & other metals big time,human intervention possible by a "clown" who decided to hold the carb in the jaws of a vice
Cheers,
Roger

[Vintageman]

Hmm looks pretty oxidized to me. The rest of that area looks brittle as well... a tap here and there may all it takes to make the rest chip away... do not think the strong jaws of a vice is needed... some erosions craters below those chips a well... I 'll have to dig through my pile of old carbs (what I have not dinged over the years) for have seen similar effects, somewhat depends how poor or porous the casting was to start. Looks like weathered brittle concrete.

Can't say for sure, just seems reasonable given, the type of metal, planet is 70% water, atmosphere 20% oxygen and time make as all degenerate and become bitter: I mean brittle

Oh, looks like you could still use it just fine

[Coyote]

Whatever it was, zinc moths, alumamites, or a ham fisted clown, it nailed all three. Of course I have no idea what these carbs went through before I got them. Everything was disassembled and thrown in one common box. I'll have a hard time ever believing it was caused by water. Not all three.
I just remembered I put 3 brand new floats in that set. I need to swap them out before I ever trash them or sell them cheap on ebay. Three new o-rings on top too. Jets are not worth saving as they are all burred up from the same clown with the wrong size screwdriver.

[pearljam724]

Maybe some clown took the term " float bowl" figuratively and installed some brass eating piranhas ? Or tried to use a jack hammer to remove the jets ?

[Coyote]

Does anyone know what casting process is used? If they are sand cast, there was probably never any good metal there to start with.

[bill in okc]

The EPA traced this 'type' of corrosion to acetic acid that is created in alcohol/water layers found in e10.
Bacteria lives in the water, eats alcohol then craps out acetic acid - a much stronger solution than vinegar.
All gas station storage tanks have a water layer in them so I expect all e10/e15/e85 gas has acetic acid in it.
Maybe not what caused this but something to consider. Check out the pic in the link.

http://www.americanmotorcyclist.com/blo ... water.aspx" onclick="window.open(this.href);return false;

[tz375]

Carbs were always dies cast pot metal - a zinc based metal known by the proprietary process of MAZAC or ZAMAC.