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Author Topic: Yamaha rd350 Road Racer Liquid Cooled!!  (Read 40767 times)

Offline teazer

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Re: Yamaha rd350 road racer
« Reply #40 on: Jun 28, 2016, 14:08:17 »
I love the shape but results don't seem to be there - at least not documented.  Do you have any data or back to back comparisons of torroidal versus flat or semi hemi designs? That I would like to see.

Offline farmer92

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Yamaha rd350 road racer
« Reply #41 on: Jun 28, 2016, 16:58:46 »
I would think you would get a tiny bit more surface area, and thus marginally better cooling, but that's just speculating...
I doubt there is really any other advantage over hemispherical heads other than getting to say you built custom toroidal heads

Offline Hurco550

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Re: Yamaha rd350 road racer
« Reply #42 on: Jun 29, 2016, 23:51:25 »
I did some reading on those, and they do seem cool, but I'm leaning towards a flat design, as I'll be doing it on an old south Bend 9
"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj
1988 tw200, the swamp donkey: http://www.dotheton.com/forum/index.php?topic=75455.0
2006 Suzuki DR650 Adventure monowheel trailer build: http://www.dotheton.com/forum/index.php?topic=75033.0
1976 BMW R90/6 farkilitious: http://www.dotheton.com/forum/index.php?topic=74349.msg882477#msg882477
1975 RD350 Road Racer: http://www.dotheton.com/forum/index.php?topic=70652.msg833688#msg833688
1976 GT250 Rebuild: http://www.dotheton.com/forum/index.php?topic=64973.new#new
Full Custom Pit Bike: http://www.dotheton.com/forum/index.php?topic=66954.new#new
1971 Yamaha 90cc twin HS1: http://www.dotheton.com/forum/index.php?topic=70498.0
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennet

Offline teazer

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Re: Yamaha rd350 road racer
« Reply #43 on: Jun 30, 2016, 02:44:05 »
I would think you would get a tiny bit more surface area, and thus marginally better cooling, but that's just speculating...
I doubt there is really any other advantage over hemispherical heads other than getting to say you built custom toroidal heads

You actually need the smallest surface area for a given volume to reduce energy transfer as heat.

The idea is that the spark starts closer to the center of the hemispherical chamber which should lead to a faster and more complete burn and more power.  The last TZ250 motors used flat topped heads and the idea there was supposedly to leave a small annular pocket of unburned gas to act as a coolant to allow higher compression before detonation kicks in.

On a street motor I think I'd optimize MSV in the squish band and go with a conventional hemi head shape.  Peg the heads to the bores and seal them with TZ O rings

Offline Hurco550

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Re: Yamaha rd350 road racer
« Reply #44 on: Jun 30, 2016, 14:30:00 »


On a street motor I think I'd optimize MSV in the squish band and go with a conventional hemi head shape.  Peg the heads to the bores and seal them with TZ O rings

By pegs you mean dowel pinned? Also, do you have a source for the tz o rings? I assume that also means an o ring groove would need to be machined into the head?

"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj
1988 tw200, the swamp donkey: http://www.dotheton.com/forum/index.php?topic=75455.0
2006 Suzuki DR650 Adventure monowheel trailer build: http://www.dotheton.com/forum/index.php?topic=75033.0
1976 BMW R90/6 farkilitious: http://www.dotheton.com/forum/index.php?topic=74349.msg882477#msg882477
1975 RD350 Road Racer: http://www.dotheton.com/forum/index.php?topic=70652.msg833688#msg833688
1976 GT250 Rebuild: http://www.dotheton.com/forum/index.php?topic=64973.new#new
Full Custom Pit Bike: http://www.dotheton.com/forum/index.php?topic=66954.new#new
1971 Yamaha 90cc twin HS1: http://www.dotheton.com/forum/index.php?topic=70498.0
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennet

Offline teazer

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Re: Yamaha rd350 road racer
« Reply #45 on: Jun 30, 2016, 15:26:31 »
Yes Dowels.  I used to order my TZ O rings from my local dealer, but I'd probably just look on line for any of the cool head Banshee O rings.  Groove can be in block or head - whichever has most material available.

Remember that O ring grooves are not round, they are "square" to allow the ring to deform into.

http://www.qualityseals.com/pdfs/groovedesignandoringinstallation.pdf

http://o-ring.info/en/technical%20manual/ERIKS%20-%20Technical%20Manual%20-%20O-Ring%20Gland%20Design%20Information.pdf

Chuck Quenzler at Supertune has details on his web site http://imageevent.com/supertune/rd350enginebuildpics
http://imageevent.com/supertune/cncpics     http://imageevent.com/supertune/rddocumentstuff



Offline Hurco550

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Re: Yamaha rd350 road racer
« Reply #47 on: Jul 03, 2016, 19:27:37 »
Thanks for the links teazer! I'm planning on drawing those chambers up soon also!

I am planning on grabbing one of those vitos cranks and some banshee poisons soon.

Been having a hard time breaking the piston loose. No manner of heat, ice, oil, wood drift and hammer ect ect. Would free this thing. I decided to try to pump it full of grease.

Used a 1/2--13 bolt, drilled a hole through it and tig welded in a grease jerk.



Just barely wouldn't slide through the spark plug hole, so I had to turn a smudge off in the lathe.


O rings to seal it, bolted the head on and started pumping.






Was a messy way to do it, but it pushed it right out until the exhaust port opened up.







Though I won't make perhaps the power, right now the r5 piston port motor is in much better nick, so that's what I'll probable go with, and use the rd350 6 speed gear box.
"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj
1988 tw200, the swamp donkey: http://www.dotheton.com/forum/index.php?topic=75455.0
2006 Suzuki DR650 Adventure monowheel trailer build: http://www.dotheton.com/forum/index.php?topic=75033.0
1976 BMW R90/6 farkilitious: http://www.dotheton.com/forum/index.php?topic=74349.msg882477#msg882477
1975 RD350 Road Racer: http://www.dotheton.com/forum/index.php?topic=70652.msg833688#msg833688
1976 GT250 Rebuild: http://www.dotheton.com/forum/index.php?topic=64973.new#new
Full Custom Pit Bike: http://www.dotheton.com/forum/index.php?topic=66954.new#new
1971 Yamaha 90cc twin HS1: http://www.dotheton.com/forum/index.php?topic=70498.0
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennet

Offline jpmobius

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Re: Yamaha rd350 road racer
« Reply #48 on: Jul 03, 2016, 20:27:46 »
You can make plenty of power with the piston port motor.  Drivability is the problem.  I had one in a drag bike doing sure enough high 10's in the quarter.  Wouldn't run hardly below 3 grand (hard to start!), but very strong on the big end.  If I could have gotten the clutch to work half way right more than once in a blue moon it would have gone faster.  Useless for the street, but the power is potentially there.  Plus I think there is some appeal from the simplicity alone, and I think they sound better!
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline ridesolo

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Re: Yamaha rd350 road racer
« Reply #49 on: Jul 05, 2016, 17:10:15 »
Glad that finally came apart for you.  Damn messy way to go, but in the long run if it worked after all else failed I guess it's worth it.  Too bad we didn't think to turn that lump over and let it sit there in that pot of boiling oil!  Hope you at least got some french fries out of that mess!   :D
“Fight on and fly on to the last drop of blood and the last drop of fuel, to the last beat of the heart.”
— Baron Manfred von Richthofen

Please check out:  http://www.VetTix.org

These are on a low simmer out in the shop:
'75 Honda CL360: http://www.dotheton.com/forum/index.php?topic=56547.0
'70 Rupp Roadster: http://www.dotheton.com/forum/index.php?topic=67459.0