Yamaha rd350 Road Racer Liquid Cooled!!

teazer

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Re: Yamaha rd350 road racer

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.
 

farmer92

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Yamaha rd350 road racer

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
 

Hurco550

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Re: Yamaha rd350 road racer

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
 

teazer

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Re: Yamaha rd350 road racer

farmer92 said:
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
 

Hurco550

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Re: Yamaha rd350 road racer



teazer said:
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?
 

teazer

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Re: Yamaha rd350 road racer

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
 

Hurco550

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Re: Yamaha rd350 road racer

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.
 

jpmobius

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Re: Yamaha rd350 road racer

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!
 

ridesolo

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Re: Yamaha rd350 road racer

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
 

Hurco550

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Re: Yamaha rd350 road racer



davedogg said:
BTW I have stock shocks in decent shape for cheap.
Shocks came in, good nick as described! Thanks man!
 

Hurco550

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Re: Yamaha rd350 road racer

Not much to update really, besides receiving fork seals and neck bearings in the mail. Von yinzer left a pile of xs650 parts in my garage, and as a rent payment, I'll be rebuilding my front end with his 34mm tubes in place of the crusty ones currently on the Rd chassis.




I dig the fairing, but it looks pretty good with the r5 body works on it too.


Still trying to get the specs I need to build the motor I want. Trying to explain it is harder. Basically, it will be a street bike, but a toy. I don't expect this to be my daily rider, but I want to be able to do an hour or so ride when I can to a vintage bike night or the Sunday ride to the twistys ect. I just know (er have heard) that these motors have plenty of power to unlock, but I don't want it to be completely useless on the street. It may see a track now and again, for fun, not competition, and a track only bike is not the end goal. I want a zippy bike to go have the kinda fun you can have on a two stroke ripping around the roads, but I don't want to be so close to the edge that I can't ride it and i don't want to only make power over 10k rpm. I think that is possible on this bike, and I appreciate you guys that have already helped me in trying to know what to do to obtain it. Will be slow going for the next couple weeks, as I'm taking a vacation for a few weeks to the hot, sweaty dirty south, but I still have this project on the front of my mind. Headed to mid Ohio tomorrow as well to see what kind of goodies I can drag home as well.
 
Re: Yamaha rd350 road racer

Sounds like you want a road tune for it, start by getting the squish right and then change the ports if you feel the need, on UK pump petrol 0.9 mm used to be the right squish, but it'd probably need to be more than that on modern US fuel as it has a high ethanol content
 

Redbird

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Re: Yamaha rd350 road racer

Subscribed.

I've got odd and end spare parts from my DS7 build. Holler if you need anything ;)
 

teazer

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Re: Yamaha rd350 road racer

Ports on those motors are relatively mild in terms of port timing and width and there is a lot of room to improve things without going stark raving mad. You don't want a race tune with powerband from 9,000 to 10,500 and nothing either side. You can go beyond a mild tune though as long as you keep the end objective in mind.

What's up with that pipe? It looks as if it is very low compared to most RD pipes. It could just be a badly shaped header pipe.
 

davedogg

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Re: Yamaha rd350 road racer

My RD's are very reliable and enjoyable. Stock is fun. I've taken my modified 350 and stock 400 on 100 + trips. But there are simple add ons to unleash some power. My experienced tuner just rode my bike the other week and was impressed (so I know I did things right) This may be overkill but here are some performance mods I did to get you started:

2 into 1 K&N Y boot (more air) ~$90
Dave F/ Dale A carb mod (more air needs more gas) I'm not an expert. I just know it works.
RZ/Banshee crossover manifold and tube (erases flat spot around 5k) ~$50
YZ125 Reeds petals (consensus for better low end torque) ~$40
Heads squished and o-ring (better compression = more power) look up Scott Clough Racing ~$190
Good set of pipes. DG's are ok. I would get SpecII ~$500-700

Using both Wiseco (forged) and ProX (cast) pistons I like the ProX more. I'm sure there is more but this is all I can think of off the top of my head.
 

Hurco550

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Re: Yamaha rd350 road racer

Redbird said:
Subscribed.

I've got odd and end spare parts from my DS7 build. Holler if you need anything ;)
Thanks a million man, I may hit you up sometime

teazer said:
What's up with that pipe? It looks as if it is very low compared to most RD pipes. It could just be a badly shaped header pipe.
I have no idea. I thought that they seem like they hang awfully low as well. I was thinking it could be something about flow with a less sharp bend. I would shorten them, but besides the basics of how chambers work, I don't know how the changes will effect (for better or worse) performance by shortening the head pipes.
davedogg said:
My RD's are very reliable and enjoyable. Stock is fun. I've taken my modified 350 and stock 400 on 100 + trips. But there are simple add ons to unleash some power. My experienced tuner just rode my bike the other week and was impressed (so I know I did things right) This may be overkill but here are some performance mods I did to get you started:

2 into 1 K&N Y boot (more air) ~$90
Dave F/ Dale A carb mod (more air needs more gas) I'm not an expert. I just know it works.
RZ/Banshee crossover manifold and tube (erases flat spot around 5k) ~$50
YZ125 Reeds petals (consensus for better low end torque) ~$40
Heads squished and o-ring (better compression = more power) look up Scott Clough Racing ~$190
Good set of pipes. DG's are ok. I would get SpecII ~$500-700

Using both Wiseco (forged) and ProX (cast) pistons I like the ProX more. I'm sure there is more but this is all I can think of off the top of my head.
I should change the title of this thread, the frame is rd350, but the motor I'm using will be the piston port r5 motor. Thanks for all the great info though!
 

Hurco550

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Re: Yamaha rd350 road racer

Also, even though I know aluminum rims aren't a need, I picked these up at Mid Ohio for a song. Both 18's, rear is an akront and the front is a tasakaga. Got both for $20 bucks, so I couldn't pass em up, not for cool old high shoulder hoops


 

teazer

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Re: Yamaha rd350 road racer

Pipe lengths are critical on expansion chambers but until we look at the dimensions of that set of pipe, I wouldn't worry too much. If necessary a new set of header could be bent up or those could be changed to suit. It was just odd that they seemed so low. Are the fitted to the barrel correctly or were they just a loose fit?

Those hoops will not work at all, but I will allow you to send them to me to spare you the embarrassment..... Great find Slip a spare spoke into each and see if the are close to the right angle for a disk hub or drum hub. Would be awesome if they are one of each.

And R5 carbs are the so called Dave F mod. That's what he basically changed RD carbs to (more or less). Y boot is good mod though.
 

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