Vintage Dirt Bike Q & A

I was planning to blank of the oil pump and use pre-mix. Frankly, I just don't trust an ancient piece of plastic tubing to inject the oil. I'm wondering if that will cause the tach gear to seize up due to lack of lubrication.

The oil pump and tach shafts/gears are in the clutch and transmission cavities and lubricated by gearbox oil. The oil pump itself is lubed by injector oil, I wonder how long it survives after the tank is removed.

Those old oil lines are surprisingly tough if not manhandled - and even when they are, a little JB Weld can work wonders. A cracked/repaired banjo-fitting joint is holding up well so far.

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

Ray, do you think it's better to use the pump or blank it off?

For me, it would depend on the particular MT250. Quite a few have had the entire oil injection system removed, and in that case it's sensible to go the premix route after blanking off the pump mounting hole if not already done.

I consider the oil injection to be a cool feature of the MT, so if the bike was complete / in good shape and the injection appeared to have been in constant use since day one, I'd keep it intact, no question. If all the parts were there but it looked like the system had been disconnected or tampered with, I'd probably replace the pump and whatever else I thought was needed to get the oil injection up and running again, provided I could find the parts. From what I've seen the system has a tendency to put out too much oil and proper adjustment is important, even if it means settting it differently from Honda specs.

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