:: R a c i n g S M :: Yamaha RD 500 V4 1985' Specifications & Multimedia

Throttle Compilation 1

Yamaha RD 500 V4 reving @ LuFo workshop

Yamaha RD 500 V4 project @ LuFo workshop

Throttle Compilation 2

Yamaha RD 500 V4 @ Estoril Paddock

Pistons: 4 x modified WISECO (56.8 mm)

Stroke: Stock (50 mm)

Cylinders: GP pedigree, new timings, passages reshaped for higher gas flow

Cylinder heads: new head volume and squish angle for 13.5:1 corrected CR

Radiator: Stock

Sparks: NGK B9VX Platinum, shorts

Exhaust valves: YPVS @ 196º

Reeds: 4 packs of Yamaha TZR 50 reeds

Carburetors: Mikunis TM 30mm, with new gigleur kit, Powerjet turned off

Air Filters: doesn't use any kind of air filter

Electric part: Stock flywheel, with new variable ignition map LuFo CDI

Clutch: reinforced, Yamaha XT 600 springs, special screws and ferodo disks

Silencers: Carbon JOLLY MOTO

Exhaust systems: JOLLY MOTO GP style modified by LuFo in length

Oil: Direct mixture in the deposit, 2%

Transmission: 15 - 42 with RK 520 blue o'rings chain.

Gearbox: Stock 6 gears

Engine maximum rotation in charge: 12 300 rpm @ 196º)

HorsePower (crankshaft): Over 130 hp

HorsePower (rear wheel): Over 110 hp

Losses between Gears (%): - | 42.5% | 23.51% | 16.89% | 11.81% | 8.88%

Crankshaft - ConnRod Attack Angle: 75.35º

Linear Piston Movement : 20.5 meters/second

Number of Explosions per second : 410

Maximum Real Velocity: near REAL 250 km/h

Wheels: ENKEI Honda CBR 600 1998', 3.5p front and 5.5p rear, both with 17', calibrated with weights.

Tires: Dunlop Radial 120/60/17' slick front & Michelin Radial 180/70/17' slick rear.

Brakes: TOKIKO 6 piston Honda CBR 600 1998' double 300mm rotors front & rear BREMBO with 220mm rotor.

Braking system: stainless steal with blue and purple terminals.

Suspension: Front Suzuki RGV 250 with White Power springs & Rear OHLINS Shock

Steering Damper: 6 possible regulations.

Frame: Stock but painted in black.

Swingarm: Stock but polished.

Chain: RK blue o'ring 520 chain.

Bodywork: Yamaha YZR 500 1991' and Yamaha R1 2005.

Headlight: Custom Ducati alike halogen bulb lights. (NRG)

Stop light: Yamaha R1 2005 red LEDs

Seat cover: hybrid sponge by LACOMOTO.

Paint Scheme: custom RacingSM.

Paint color: Honda Hornet 600 blue.

After the few engine transformations, about the Jolly Moto exhausts, the +4mm carburetors (Mikuni TM 30mm instead of the stock 26mm ones) without using air filters and with new gigleurs, raised the compressio ratio for 13.5:1 and the cylinders slighlty tuned, we believe this 500 V4 is giving nearly 110 engine horsepower.
The power increment is normal, we're talking about 23 hp, 5.75 hp increment for each 125 cylinder, (about 26.4% of output power increase on this engine, in a high revy way with the maximum power placed on the last band of rotation, just like it happens on the 2-Stroke MotoGP bikes, to maximize the real top speed and accelerations in medium/high velocities).

On the other hand, the chassis of the Yamaha RD 500 V4 1985' behaves very well in curve, had to the fact we use good tuning suspension of the Suzuki RGV 250 front end, and the OHLINS rear shock.
The front slick Dunlop GP tire (not SM) 12/60x17' and the rear slick Michelin tire 180/70x17', the braking is guaranteed by the double brake disc with 300mm using TOKIKO 6 pistons and stainless steel, that allows an impressive and awesome braking power.

Now we pass to the study of the Yamaha RD 500 V4 1985' gear box, from which we can take many conclusions about the performances and losses between gears in a percentual way.

So, we now give the graphic relative to the Jumps/Losses Between Gears (%) for the Yamaha RD 500 V4 1985':

As we can see through the Graph "Jumps Between Gears (%) Yamaha RD 500 V4 1985' ", that the gearbox is appropriate for high speed bikes since the losses between gears are very closed, specialy between 5th and 6th gear with only 8.88% of loss. This gearbox purpose is good, very well spaced out between gears, for good use on low-mid ranges and the low loss in the last 2 gears make it for the high-revs.
Now we're going to present the thematic of the Real Velocities in Each Gear, also comparing the stock version and the actual one. Relatively to the top speed, it's necessary to have in count some aspects:

The difference in real maximum speed in each gear between the stock version and the tuned one is notable. The difference of real maximum velocity in 6th gear between the stock version and the slightly tuned one with 16 - 42 secondary transmission is about 18 km/h and 33.64 km/h for 17 - 42, a nice value since real 266.5 km/h is like 285 km/h in the digital instruments of the newest 1000 cc superbikes.

Using trigonometry, more precisely, the " Pitagoras Theorem ", we can calculate a very important index, and at the same time, interesting, because it explains if an engine is prepared for Motocross/Enduro or if it has a GP source.
As we can see, the conclusion we get is that the Yamaha RD 500 V4 with the actual engine tuning possesses an ConRod-Crankshaft Attack Angle of 75.35º, this value is very near the average presented by many MotoGP/Velocity/roadrace engines.

Values rounding 75.5º - 76.5º favour the high rotation regime, with short power and high bands, besides reducing the friction piston-cylinder (and from there more durability), confer one superior easiness in effecting greaters regimes of rotation and more keeping them of untied form and without effort during more time.
We are before the phenomena of Leverage: the longest the part that makes the effort, the more the force is necessary to effect the "work" in question, that's why we say that it possesses less Leverage. But there is a point on the RPM range of revy engines, where this process gets upside down, or in other words, we can get advantage of long conrods in roadracing high rpm engines (e.g.: Aprilia RSR 125 GP bike, with square engine and 115 mms conrod length and 13300 RPM (~24 m/s), with a short leverage index, factor that empoorless the low and midle RPM's but empowers the last 2000/3000 RPM and get them quicker.