RZ/RD 350 & Misc. 2-Stroke Tech BBS

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 Post subject: Rd 350 engine mods
PostPosted: Mon Jan 08, 2018 2:19 pm 
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Joined: Sun Jan 07, 2018 2:28 pm
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could anyone tell me what the different stages refer to when having an rd 350 engine ported? stage 1, stage 2, all the way up to stage 5. I am having gary shumake build me an engine but I'm not very well versed in all that each stage means or what to expect from them. thx...j


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 Post subject: Re: Rd 350 engine mods
PostPosted: Mon Jan 08, 2018 2:29 pm 
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Joined: Mon Aug 10, 2015 8:57 pm
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Location: Ottawa, Canada
Each builder is different. Different stages of tune/high strungness plus additional add on parts, (pipes, carbs, ignition)

The higher the stage, the more often parts will need to be replaced and it puts more stress on the components that originally intended, ie bearings, rings, pistons, cranks etc.

Ask the builder what they're different stages mean.


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 Post subject: Re: Rd 350 engine mods
PostPosted: Mon Jan 08, 2018 9:56 pm 
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Location: Alberta, Canada
My advice is to only have the ports blueprinted, and cases matched with the jugs. If you want more power after that, concentrate on flow in and flow out. (Remove the air box for K&N filters and put pipes on with rejetting).

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 Post subject: Re: Rd 350 engine mods
PostPosted: Tue Jan 09, 2018 2:04 am 
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Location: Honolulu
Gary will take care of you. He can be moody however his work is excellent.

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 Post subject: Re: Rd 350 engine mods
PostPosted: Tue Jan 09, 2018 3:02 am 
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Gary @ Spec 2 explains on his website exactly what his Stage 1-3 engines are. It's been that way & unchanged for 30 years. Yes he can be socially difficult...lol He does not suffer fools, nor those looking for free advice but he does Good work, but you better ask what his turnaround time is, my friend was quoted 10 months for his motor. Gary's must be well into his 60s and has had alot if setbacks, so be prepared for a wait, but that was 4 years ago maybe things have changed for the better.. If that's too long for you, I'd get your bottom end built as a +4mm regardless, but I'd look no further than Scott Clough for your port work, He's utterly fantastic...and quick turnaround.
I've never heard nor read about a Stage 4 -5 offered from anyone? but times change.
I had Gary build me one if his 372cc big bore motors Waaaaay back in 87-88. Frankly, no one built a faster RZ motor back then. And the motor was bulletproof, I put close to 20,000 hard abusive or more miles on that motor, and it ran like a champ when I sold it
Just like the infamous magazine article about Gary's 350, my RZ could rip the 1/4 mile in the mid 11s...do the math on a drag race weight /h.p/time drag calculator site, you will see how impressive that is, and consider this was built long before a Banshee ever existed.
I have no idea what purpose you intend to use the bike for, but generally speaking stages are as follows .
. STAGE 1 Is a basic clean up, reeds,carbs (Optional), head /squish correction ,exhaust pipes and a 16 tooth front sprocket.
STAGE 2 As above, but with more aggressive porting , combined with larger carbs often 30-32 mm which brings substantially more power in the mid-high RPM range, while still maintaining decent "streetable" characteristics.
. STAGE 3 All of the above, but again more aggressive port work, with power generally being greatly increased in the 9000-10,000+ RPM range, and often with 32 or larger carbs.
Substantially quicker on a road course, but on the road there's less power avail for street riding in the lower RPMs due to the fact that it's designed to deliver power way up in the redline (Think Yamaha R-6 ) as a Simplistic example.

If your racing,dont worry too much about longevity, as you will be replacing your crank and pistons anyways probably once a season, but for the road, you will get thousands of more miles out of it.
For a street bike I'd recommend, thst (NOTE*) If you have a US spec bike, You will want to emulate the later Canadian spec port work or a average Stage 2 level build, then add Pipes of your choice, but I recommend Toomey pipes over all others combined with their jet kit on stick carbs, add reeds, I like TDR (Tony Douglas Racing) fiberglass petals. He's a member here as well. Can combine these mods with a corrected cylinder head and a 15 tooth sprocket, and you will have a RZ that's reliable as it better than stock, but so much faster you won't think it's the same bike.
Gary builds good pipes, his race spec pipes are proven over 3 decades, but for me the Toomey deliver much better acceleration for a street bike. But either choice will put a smile on your face, and should you need a new set, they've each been here for 30 + years and only a phone call away.
That is the basics, many builders especially Banshee based builders have their own tweaks here & there, but basically these modifications follow suit across the board.
Research Banshee port jobs, you have various Trail, MX ,Dune, Drag port jobs, which emulate the above listed Stages. It's often where do you want the power delivered, you can't have both, but you can find a nice compromise that should provide you with results that will suit your bike's intended purpose.

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