Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => Restoration => Topic started by: BRT-GTR on July 18, 2015, 11:35:01 AM
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Hi All,
Decided to clean the carbs on the latest GTR this afternoon. Gave them a wash off on the outside in kerosene - came up a treat. However, while I had them upside down, drying them off I noticed white powder coming out of the bowl vents, so pulled the float bowls off. Photos of what I found.
This is the bike where I suspected some idiot had pressure washed the air intake chambers and had filled the crank case with water. I think this confirms it. I'll clean them up but I don't think they will be useable. There's probably a cubic inch powder in each float bowl but I can't see much metal loss from the alloy. Anyone know what's going on here. ( Don't say corrosion !! ;D :D ;D). Fortunately I have spare pair of carbs.
Brian
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Another photo. Brian.
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EVAPORUST! (can't hurt to try, it got that same white stuff out of the bowls & insides of the petcocks I cleaned... ;D )
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Brian, the yellowish crud is probably evaporated gas, but the white powder is (as you say) almost certainly corrosion (sorry, I said it ;D) caused by water standing and then evaporating in that bowl. Not sure what the chemical composition is of the white stuff, but this is common in aluminum (and aluminum alloy) areas that are subjected to high moisture level and enclosed. I found this in a front brake from a very rusty parts bike.
...bert
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Hi All,
Bert, the yellowish tinge is where the kerosene had found it's way into one of the float bowls. The powder is an oxide but I wonder whether it has leached one of the components out of the carb body alloy or the zinc out of the brass floats/jets etc. You would think there would be obvious signs of metal loss but everything seems reasonable.
Mike , it will be going in the evaporust, nothing to lose, except big chunks of alloy ;D ??? ;D . Certain alloys will crystallize with age and become brittle, like the oil pump outlet unions. Might be late next week before I can try it.
Brian.
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my original left carb had white powder in it .I would bet that the fuel tap was left on and never drained when parked up . it probably would be lead oxide .
on another note my old amal carbs have blocked pilot jets with a white gooey crud they say that the old alloy reacts with ethanol blended fuel to produce this muck (though its never had blended fuel in it) maybe the same with old mikuni carbs