THE Two-Stroke Superbike - the 2008 TSS RS500GP

The RS500: Ultra-Light, Massively
Powerful and Grand Prix Engineered


The TSS RS500GP represents for us, and for a great many sports motorcycle enthusiasts, the ultimate 'Bike That Should Have Been Built.' A rip-snorting dream bike with more grunt than a piggery at chow time, and with a singing top-end power hit to silence all two-stroke naysayers.

Well, now it is being built. And the best news is that it is developed, tested and built by a 500cc Grand Prix Engineer. Yet the RS500GP is more affordable than a middleweight Superport four-stroke. That's because we at TSS are phenomenally passionate about advancing the cause of the two-stroke road and race bike.

We have made it our business to sucessfully produce a viable alternative to the four-stroke sportsbike status quo, so our customers can enjoy the sharp crack of high-density power that only a two-stroke engine can provide.

Yet all of this started off humbly enough, as a simple plan to try out a Cheetah 485cc engine in an Aprilia RS250 chassis. The plan paid off, big time. And word got around about the spicy hybrid, and excited emails and 'phone calls came in day and night from all over the world, and with almost evangelistic zeal they said, "A modern 250GP style bike with a 500cc two-stroke engine!? I want one; I want to build one; just don't tell the missus!"

It was like a scene from Monty Python's 'The Life of Brian,' with all these two-stroke starved pilgrims looking for a Messiah. And the truth is, you just about need a miracle to engineer one of these things properly, or at least a miraculous overdraft. The cost to develop a bike like this to the highest standards is far beyond the budget of all but a few wealthy individuals, but everything is just so right about the bike; more people deserve to enjoy the ride.

Fortunately for the two-stroke fraternity, a chance meeting with famed Grand Prix Engineer Wayne 'Wobbly' Wright unlocked the key to really perfecting these promising hybrids. Over a career spanning more than 30 years, Wayne has designed and built and tuned the best. As a 500cc GP Engineer, he built race-winning pipes leading racing teams. His engines and pipes and ignitions have won GPs and Championships all over the world.

 


And what Wayne saw in the early RS500 was a devlishly brilliant scheme in the making. He saw the potential for building an epic canyon-blitzing steed that Yamaha's and Aprilia's engineers would loved to have built, if the bean-counters had allowed them. A true no-holds-barred two-stroke rocketship with a fat bottom end, massive midrange and lung-collapsing top end rush.

The RS500GP went into development and testing. The Two-Stroke Shop (TSS) was born, and with it the world's first Direct-to-Customer GP Engineer-Developed Motorcycle. The RS500GP ushers in an exciting new concept: for the first time ever, the pure undiluted two-stroke GP experience is available for all road and race riders.

The whole engine was redesigned and optimised - (please CLICK HERE for more detail on TSS500 engine development and technology) the whole inlet tract was custom-built, flow-matched and set at exactly the right length, just as a 500cc GP machine would be prepared.

Custom-designed, lightweight Wossner flat-top race spec pistons were forged, and crankshafts manufactured to precisely the right Balance Factor for the reciprocating asemblies used. This exacting process of balance-matching all engine components is more typical of MotoGP pit lane, but it's just another example of TSS's relentless pursuit of excellence.

The end result is far more than a mere race replica. Combining the massive grunt of TSS500 power mated to the unbeatable chassis of the flyweight Aprilia RS250, like peaches and cream we have a match made in motorcycling heaven.

After building the first few RS500s and seeing how great they are, we decided to produce a large batch of components and offer the RS500GP as a production bike, along with TSS500GP engine kits as well as its stablemate the TSS500LC.

We believe a sportsbike should have the ability to render you a breathless, raving gibbering fool. A bit like a teenage girl at a boy band concert, but with the difference that this is a relationship that does get consummated.

We believe motorcyclists deserve a truly exhilarating ride - and the RS500GP is The Ride of Your Life.

Just take a look at this dyno chart; it reveals that the TSS500GP engine developes some 30% more torque than a 600cc Supersport engine, in a bike that is 35kg lighter!

The raw numbers alone - well they just stack up. A 112HP engine in a 130kg bike, with two mighty 250cc pistons churning out gutsy torque even at low revs.
This is not like the old-school four-pot 500s with their tiny 125cc cylinders and consequently 'boggy' lack of response when off the pipe.

Just think of a bike with 2 x CR250 motors, and you're getting close to understanding how strong the TSS500GP mill pulls from low revs.

And yet, due to our revolutionary new curved power-valve blades that follow the piston profile more closely than existing flat-blade designs, the strong bottom-end and midrange grunt is achieved without compromising top-end zing.

So you get all the righteous benefits of the two-stroke engine - an avalanche of torque straight off idle, building through a rollicking midrange and culminating in a classic two-stroke whack over the head top-end rush.




So never mind the enviro-hippies and the adherents of 'predictable, controllable, linear four-stroke power.' No, it's time to take this beast to the streets and the tracks!

The best deal of all is that this project paves the way for anyone who is interested to get into their own RS500. We can supply complete RS500 bikes; everything from chassis, engines, etc - or we can adapt your existing RS250 with a custom engine mounting cradle to accept the potent TSS500GP engine.

Whether you fancy the ultimate two-stroke track-day tool or indeed the last word in a canyon-blaster, look no further, because the RS500 is here to satisfy your every two-stroke desire.

This is not just a Performance-Enhanced Blast Down Memory Lane - these engines usher in a whole new era of two-stroke technology and performance - the long-awaited age of the Two-Stroke Superbike! Suspension and tyres and brakes have evolved - now let's bring on the power!

All enquiries about RS500s/Kits/Parts, including TSS500 engines; expansion chamber exhausts; RS500 engine mounting cradles; offset sprockets; Ignitech ignition systems etc. to Steve at offbeat@iinet.net.au please. Tel. 0427 774 285 or from outside Australia: +61 427 774 285.

The Two-Stroke Shop is also making high-capacity radiators, designed for running TSS500 engines in the RS500 as well as the Yamaha RD/RZ chassis.

You are welcome to get in touch if you would just like to chat about the bike or bikes in general, especially two-strokes!

Thanks for your interest, keep coming back 'cos there will be a lot of progress on this page, and happening quickly too.

The Two-Stroke Shop
Web: www.twostrokeshop.com
Email: offbeat@iinet.net.au

Cairns Motorcycle Tours and Hire
9 Compass Close, Edge Hill
Cairns 4870
Tropical North Queensland, Australia
Tel. (In Australia): 0427 774 285
Tel. (Outside Australia): +61 427 774 285
Web: www.bikingaustralia.com
Email: offbeat@iinet.net.au
ABN 11 346 987 340

BACK TO HOME

 

Comparisons: RD/RZ350 cylinders at left; TSS500 monoblock cylinder at right

Note the massive CR250 intakes of the TSS500 cylinder. Just imagine, running 2xCR250 power in a 125kg bike! Then imagine 2xrace-tuned CR250 power in a 100kg race bike!!!

Bit of a difference here! Stock RD/RZ350 bore, at left, is 64mm, while the TSS500 is 73mm,
with a +4mm stroker crank to bring capacity up to 485cc.

 

 

 




Note the four huge side inlet boost ports of the TSS500 cylinder compared to the old-hat RZ architecture.
TSS500 cylinders are all-alloy, Nikasil-plated - so no more rebores, and superior thermal dissipation properties compared to the old iron liners of the RZ/Banshee.

 

 

 

 

 

What's so special about the TSS500 Engine?

Lots. Just take a look at these port pics, right and below, and realise that this is a truly no-holds-barred 500cc two-stroke twin built with modern porting specs & technology.

With two exhaust boost ports per cylinder and two massive inlet boost ports as well as six transfer ports, this is porting on an inspiring scale.

 

 

 




 


Inside the TSS500's massive intake mouth: A huge bridged main inlet port and two large inlet boost ports per cylinder make for a seriously heavy-breathing motor.

 

 

 

 

 

 

 

 

Three exhaust ports including two exhaust boost ports = Much better emptying of the spent charge

 

 

 

 

 

 

 

 

 

 

TSS500 cylinder porting: Here you can clearly see the TSS500's three exhaust ports, incorporating two exhaust boost ports, also the six transfer ports/two inlet
boost ports per cylinder.

 

 

 

 

 

 

 

 

 

 

 

 


Engine Mounting Subframe

Behold - the custom-designed RS/RZ engine mounting cradle.
This cradle accommodates the curved RS radiator and the RZ engine stabiliser bars.

The RS500 engine mounting cradle bolted up to an RS frame. Lovely!

 

 

 

 

 

 

 

 

 

 




Primary Drive Ratio Options



Options range from the stock RZ/Banshee 2.86:1 helical
gears, to straight-cut primaries in ratios of:

2.86:1
2.68:1
2.36:1

 

 

Clutch
We use and recommend Barnett clutch baskets and pressure plates. Equipped with stainless
steel inserts on the basket fingers to eliminate grooving of the fingers and tempered steel faces
on the pressure plates, these clutch components are guaranteed to never wear out.

We also use Barnett Cryo alloy drive plates, which have undergone a process of deep cryogenic tempering; involving treating the plates at minus 300 degrees Fahrenheit to create a significant increase in abrasive wear resistance and durability. The end results are a longer life and less chance of breakage.

The plates are then hard anodized for added durability. These plates will not contaminate the oil like typical plain aluminum plates. They are also about one-third the weight of steel drive plates resulting in less rotating mass in the clutch assembly and quicker throttle response.

www.barnettclutches.com

 

 


 

 

Offset Sprocket




28mm offset sprocket allows the engine to be centred in the frame while clearing all frame,
swingarm points. Max gearbox sprocket size is 17T.

 


Modified Rear Shock Linkage/ Dogbones

The addition of the TSS modified dogbone/suspension rocker unit is necessary because we need to keep the
123mm belly of the pipes - we will accept no compromise to the optimised expansion chamber design -
whilst ensuring perfect suspension functionality. This mod also saves weight, and replaces the OEM
mild steel dogbones with thinner yet stronger custom-designed stainless units.

 

The Two-Stroke Shop
Stephen Rothwell and Wayne Wright

www.twostrokeshop.com

info@twostrokeshop.com

9 Compass Cl, Edge Hill
Cairns, Queensland 4870
Australia

Land Tel. (In Australia): 07 4032 1708
Land Tel. (Outside Australia): +61 7 4032 1708

Mobile Tel. (In Australia): 0427 774 285
Mobile Tel. (Outside Australia): +61 427 774 285

 

 

Special thanks for the success of this project are due to:

Sotaro Inoue of Inoue Boring in Japan -
http://www.ibg.co.jp
Hank's Engineering, Cairns -
http://www.hertmotorcycles.com
Dean & Brett, Bikes and Bits wreckers in Cairns -
extremecairns@yahoo.com.au

 

BACK TO HOME