I enjoyed your video and step by step tutorial on the carb. My 1972 XL250 K0 is like the twin to the one you worked on. A nice original survivor. A while back, I bought a cheap Amazon rebuild kit and had the same problem with the o-ring to seal the float bowl. I looked through my spare carb parts and found a slightly larger one and cut it to size and used a dab of gasket to make sure the 2 ends were sealed. I'm more of a 2 stroke guy and prefer working with Mikuni VM carbs. The Keihin o-rings on the needle & seat, and the main jet will be a problem again when the ethanol in today's gas turns the rubber to black goo. Here in Canada, as of 2023, all of our fuel now has a minimum of 10%. There were still some premium fuels with no ethanol until this year. There is a point to my rambling on about fuel. I several bikes, making it impossible to use them all regularly. I add stabilizer to the gas to prevent deposits from blocking my pilot jets. I can't say for sure if it is the ethanol or the numerous additives, but I find that all it takes is 6 weeks with very small pilot jets. If I'm not using a bike for a while, I will drain the tank, carb(s) and petcock, but if I forget, the stabilizer will generally work for a year. I cleaned my carb again yesterday, and my XL250 starts first kick for now. I just have to remember to drain it for the winter, before putting it away for the season. My ultrasonic cleaner has become invaluable.

I'm working on the same bike 👍👍carburetor rebuild..

Ronnies Race Shop!

How did you get the center jet out?

Can you tell me where you ordered the leaf spring from (the clip that holds the main jet in and touches the bottom of the float bowl)?  I am working on my 1975 XL250 and snapped the two tangs off while trying to tighten it up a bit.  It doesn’t even look like it has its own part number so I can’t seem to locate one.  Also, I couldn’t get my round o-ring to hold long enough to attach the bowl so I ordered a preshaped one from “4into1”.