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Yamaha TZ700 TZ750 expansion chambers
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Author:  kawi3cyl [ Thu Jan 26, 2017 1:46 pm ]
Post subject:  Yamaha TZ700 TZ750 expansion chambers

http://www.ebay.com/itm/Yamaha-TZ700-TZ750-expansion-chambers-/142252812338

"Lightly used experimental Yamaha TZ700 TZ750 four into two expansion chambers. Rare. The have Vesco written on them, but from the research and have conducted the pipes most were most likely fabricated by Rob North and used by a California desert/road racer named Ward Ring (but I am still trying to confirm this information). Please contact me if you have any questions, or if you have any spare TZ700/750 parts."
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Author:  Ja-Moo [ Thu Jan 26, 2017 4:29 pm ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

interesting...... :wtf:

Author:  H2RTuner [ Thu Jan 26, 2017 6:08 pm ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

I remember those......no, thanks.

Author:  Ja-Moo [ Thu Jan 26, 2017 7:40 pm ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

is the 750 a 2 up, 2 down with the inners and outers paired?

Author:  H2RTuner [ Thu Jan 26, 2017 9:26 pm ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

Yup, John, as you said, 1 & 4 are paired to fire together, 2 & 3 are same pairing, 180 degrees later, so, TDC 1/4 fire, 180 degrees later, 2/3 fire together, then back to 1/4, etc. In essence, two "Twingles, 180 degrees apart. If these pipes were to work to make torque, the pairing, one would think, would be 1/2, 3/4, not 1/4, then 2/3.

The only thing I heard from Von Desco (our nickname for him) was he was seriously thinking about changing the firing order, 1/2 together, then, 3/4 together. Then, in theory, these pipes would have the right pairs feeding them. They were designed to help with torque, because the streamliner was a lot heavier than a TZ bike, but, it had TWO of these engines in it.

You'd have been very surprised at all the screwball ideas that came up back then, some were hilarious, some down right scary. Like the Laverda 4 stroke inline 3 cylinder, first iteration had 1/4 pairing (switching back and forth at TDC, one firing, one on overlap, swap ends the next TDC of that pair), with the center cylinder 180 degrees apart. Second design was much like the Yamaha 750/850 triples, 120 degree firing, with one complete crankshaft rotation a dead player.

Like you said, "interesting".

Author:  husson73 [ Fri Jan 27, 2017 4:47 am ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

part of history if this has been tried on the streamliner,, thanks for infos Tuner :mrgreen:

Author:  H2RTuner [ Fri Jan 27, 2017 6:16 am ]
Post subject:  Re: Yamaha TZ700 TZ750 expansion chambers

Don even tried to make the engines fire @ 90 degrees, by releasing the crankshafts like one of the old inline Honda road race two stroke engines, but was unsuccessful in his attempts. Even the last batch of road race V4's, either straight on, or "Big Bang" all fired two cylinders simultaneously.

Also, those pipes have straight primary tubes out of the exhaust ports, and huge center sections, built for torque only. They had to cut off way early in the rev range, way below the RPM potential of the TZ 700/750 engines.

Vesco did a lot of very strange things with those engines, not much of it all worked as planned.

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