Parting Daytona - FPP Pipes

[RDFL]

https://www.ebay.com/itm/203449938184 He is parting whole bike.

[85RZwade]

Already disassembled and selling parts separately 

[RDFL]

https://www.ebay.com/itm/194129266686?hash=item2d330187fe:g:J6sAAOSw5HZgnw3J

[rodneya]

Pretty sure those pipes were not made for a Daytona with those sexy extenda brackets

[RDFL]

I noticed that too.

[rodneya]

What exactly are the exhaust butterfly valves meany to do, and were these a US only thing? Like the power killing Cats in the us RZ exhausts?

[RDFL]

Engineers did this by taking advantage of the EPA's test procedure, which measured emissions taken in four different modes—at idle, during acceleration, while cruising, and during deceleration—and averaged the results. Because two-strokes spew a lot of unburned hydrocarbons during decel, engineers figured they could get the bike's average number below the maximum allowable figure by using clever technology that limited this effluent via a combination of butterfly valves located between the exhaust ports. These valves simply closed off the ports and were powered by a vacuum-operated accumulator, which closed the valves on decel and used a throttle-position vacuum to open them when the rider cranked open the throttle. Small bypass holes in the butterflies kept the engine from being totally strangled at idle and on deceleration.  https://www.motorcyclistonline.com/1979-yamaha-rd400-daytona-special-two-strokes-rd400f-roots/