Vintage Dirt Bike Q & A

I'm in the process of rebuilding the carb on my MT250. I noticed that the copper overflow tube has a crack it's entire length. It's almost like it was put in as a rolled piece of copper rather than a tube. I soldered the crack. Will that hold up?

The other issue is that I noticed a piece is missing that is NLA. It is the M shaped piece of spring steel that goes under the cap between the spring and jet needle where you attach the throttle cable. Will that effect anything? What is the purpose of that part? Does anyone have a spare they could sell me?

Thanks.

You're the second person here to mention a cracked overflow tube on an MT250 carb. Solder should hold up just fine. I'm hoping my friend's has a cracked one too, as despite my best efforts his still leaks like a sieve.

That M-shaped spring thing fits into a slot in the lower I.D. of the slide, to hold the round spring seat / needle retainer in place. I've found it to be a real PITA during needle adjustments and don't use in in any of my carbs; if you want one, I've got at least a half-dozen here and will be glad to send it to you.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Thanks Ray. I guess I'll give it a try without the spring.
The solder held water but not gasoline. I'm guessing the aluminum was too much of a heat sink to get a good joint. When I tried to heat it up more, it just starts destroying the tube. So, I went to a hobby store and got a new piece of tubing and replaced it. I put a little red loctite on it to keep it from working loose.

That should work out well. Good call about the hobby shop, they can be great sources for metal and plastic tubes / sheets / etc.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric