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Being a two-stroke rider as well (YZ's, CR's, RM's), I've gotten extremely used to shutting off petcocks on everything in the garage when not in use. Thank god that it was pounded into my brain from a young age!

A few weeks ago I was playing around a bit with my CB450, and went to get the trickle charger to keep the battery in check. I returned to find that my left carb was spewing fuel onto the garage floor at an alarming rate. Ran to the bike, shut off the petcock, and started to investigate.

Sure enough, the float was full of fuel. No big deal...it's fixable. I drilled a small pin hole in the side, set it on a cotton pad, and left it sit in the sun to get rid of all that fuel. In the meantime, I checked the other side, and sure enough there was fuel in there also, just not enough to yet cause a problem. So, here's the process.

I eventually got them both drained, delicately cleaned them up until they were ever so clean and shiny, and with the best precision that I could muster, soldered the pin-hole, and hairline cracks that I found in both. I did consider using my mini pencil torch, but quickly decided against it, and went for the soldering iron instead to keep it concentrated so I wouldn't break the seals or the solder on the tab.

It worked like a charm! Until a week later. Riding the CB450 around a bit, and it starts acting up ever so slightly. Return to the garage, and the same thing. Repeat the process, problem fixed. This has happened a total of 4 times, but only twice with the right, and all four with the left. Now there is just too much solder, and the left float bowl is too heavy to do it's job. I did order a new one, and it should be here in a few days. But I can't help to wonder...

What to the long-time experienced do when these cracks keep appearing, only to solder them and have new ones emerge? Is there a separate trick that I don't know about for this instance? I can only imagine how difficult it is to find new bowls for some of the older models, let alone for my 71. Any other experiences or tips/tricks would be appreciated!
 

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Sensei
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It's a real tricky proceedure.... The floats themselves must be annealed to keep the metal soft while the "arm/pivot/tab" part has to remain semi-hardened to retain its "working/able to apply pressure" status.... The entire assembly has to be heated , then the float "tank" part(s) only have to be quickly quenched in a "pickling" solution (to anneal and clean), then the rest is slowly completely immersed so the "arm" is cooled at a greatly reduced rate (cooled, but slowly, after the pickle has drawn most of the heat out down through the float ).... This keeps the float tanks "soft" while the arms don't get fully annealed and retain some strength.... It's an "Art/Skill" that a jeweler could probably explain better....or a metallurgist....
You are probably better off just replacing them.....
 
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