Now I've seen it all!
I was looking over some RD400s on Ebay when I came across this '77 for sale. Noticed this odd piece of copper on the oil pump and then found an explanation in the description. :eek:
"I noticed that the exhaust began to have less of a blue tint to it, so I added a simple piece of crimped ¼" copper tubing about ¼ inch long to the two cycle oil pump mechanism that improved the amount of oil getting to the fuel mix. Whether this was a cure or not I don't know, but I got more blue smoke and that made me happy. Since I am no expert,it might need a tuning once you take delivery, but it should start,idle and perhaps you should get to ride it right away."
https://www.ebay.com/itm/1977-Yamaha-RD400/324192002686
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That is quite the sales pitch.
WTF? Also. Who replaces 30 year old tires and decides to let the tubes ride?