Vintage Dirt Bike Q & A

Need of any help please! I have a 1976 Honda MR250 that is driving us crazy. It starts, but won’t idle and runs like shit until it reaches about 3000RPM… then it takes off… on the lower end of the power band, it acts like it’s choked or running to lean or too rich…but, eventually at somewhere around 30% throttle and higher it takes off like a rocket.

We have cleaned carb, checked timing, air box, brand new bore and piston, rings, crank, rebuilt top and bottom ends… but are still at a loss…

Can’t find a carb rebuild kit, but wondering if jets are wrong… although I do have 2 of these bikes (identical) and we switched the carbs around and it still was doing the same thing… (the other bike runs great)

Try turning your air screw all the way in until it bottoms, then ride the bike. Does it run at all at low revs?


Which is it - too lean, or too rich? Does it idle with the choke on?

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 will try this tonight and let you know.