Yamaha YZF-R6 (2003-2006): Review & Buying Guide

Yamaha ramped up the supersport 600 market in 1999 with the launch of its original YZF-R6, a smaller sibling to the then all-conquering R1. The R6 boasted more power, a more sophisticated chassis, and a level of finish not seen in the class up to that point, taking supersport 600s from being built-to-a-price disposable middleweights into genuine sub-750cc superbikes.

By 2002 the R6 was showing its age, however, with fresh models from Suzuki, Kawasaki and Honda snapping at its rear wheel. For 2003 Yamaha launched the second generation YZF-R6. While it looked similar to the first model in silhouette, almost all of the ’03 machine was new. The most obvious updates were fuel-injection in place of carbs, new five-spoke wheels, and even sharper styling.

Power was up against the previous bike by a claimed 4bhp, as was torque, marginally, by 0.3lb.ft, while overall weight was trimmed by 7 kilos to 162kg. Many R6 connoisseurs – and there are a fair few out there – consider the ’03-’06 model to be of the very best models; not quite as rev-mad or compact as later incarnations, yet fun and fast enough to work well on both road and track. That makes them a smart buy on the used market, as does price. Tidy examples can be had from around £2800, while low mileage minters make around £4K. Compare that cash to what’s available new or nearly new for similar money and it’s clear that these second gen R6s are great used buy.

Pros & Cons

2003-2006 Yamaha YZF-R6 - Prices

2003 Yamaha YZF-R6 (03MY)
New frame and swingarm (Deltabox III chassis), 5-spoke wheels, fuel injection, sharper styling, new clocks – thorough update on previous models. Claimed 123bhp. 162kg dry weight. Colours: blue/white, red/black, yellow/black 

2004 Yamaha YZF-R6 (04MY)
New graphics including black bellypans. Colours: blue/white/black, grey/white/black, red/white/black

2005 Yamaha YZF-R6 (05MY)
New 43mm usd forks, radial front brake calipers, minor engine mods. Continued into 2006 as a black only option. Limited edition VR46 special also released in 2005 with Valentino Rossi inspired sun and moon graphics. Colours: blue, black

Yamaha YZF-R6 values
Rough: £1800 - £2300
Tidy: £2800 - £3200
Mint: £3500 - £4100

2003-2006 Yamaha YZF-R6 - Engine & Performance

The 2003 R6 was far from a mere refresh, and its engine is a case in point. Yamaha went through the entire unit, updating or completely redesigning more than 90% of the internals. While the motor’s bore x stroke remained 65.5 x 44.5mm, giving 599cc, the cylinders on the new bike were a sleeveless design plated with a ceramic-composite to reduce friction. New forged pistons (previously cast) reduced weight and increased component strength and reliability, while 10% thicker top rings improved sealing and reduced flutter at high rpm.

The valvetrain also got attention; valves were given increased lift (from 7.8mm to 8.2mm) and stiffer springs to maximise mixture flow at high rpm, therefore boasting power. Most significantly Yamaha ditched the first gen’s 37mm carbs for an all-new fuel injection system firing mixture into the cylinders via 38mm throttle bodies (enlarged to 40mm for 2005, along with shorter intake funnels that vary in length between the inner and outer cylinders), with a larger pressurised airbox to boot. A larger curved radiator also helped reduce heat loses that come with extra power.

While the engine’s power gains over the previous engine only add up to 4bhp and 0.3lb.ft, a weight saving of 7 kilos from the overall package helped make the 2003 R6 more responsive throughout the whole rev range. It’s a motor that thrives on revs, peaking at 13,000rpm and revving to 15,500rpm should you desire. As supersport 600s go the 2003-2005 Yamaha YZF-R6 remains an exciting ride that requires commitment from its pilot, but delivers huge thrills in return.

Such a high performance engine requires meticulous maintenance, however. Oil changes every 3000 miles are best practice – the book says every 4K, especially if you partake in the odd trackday (make it every 1000-1500 miles if you’re a regular track rider), Valve clearances require inspection every 26,600, but it wouldn’t hurt to check every 15,000 if you’re using your R6 hard.

2003-2006 Yamaha YZF-R6 - Handling & Suspension (inc. Weight)

The biggest change to the R6’s chassis from first to second generation was its frame. An all-new aluminium beam Deltabox featured just two welded sections; in comparison to the previous model’s used 16. This was thanks to Yamaha’s then new ‘controlled filling ally die-casting’ process, which allows control over the volume of flow of moulten aluminium into the die. This in turn reduces the number of air bubbles trapped into the finished aluminium, creating a stronger product that, due to increased strength, can be thinner and therefore lighter. Yamaha claimed the ’03 R6’s frame to be 0.5kg lighter yet 50% stiffer, putting it on par with that of the R7 racer.

The chassis is dimensionally different to the old bike, too. A 10mm longer swingarm and repositioned swingarm pivot (10mm closer to the front sprocket) aid traction, while moving the steering head and yokes back added 5mm to trail (86mm), although rake remained the same at 24°. Lighter (by 4%) five spoke wheels lessened unsprung weight to further quicken steering and turning – tyre sizes remained 120/60 ZR17 and 180/55 ZR17.

Yamaha made further changes for 2005, again tweaking the steering – this time 0.5° extra rake, 9mm more trail and an additional 5mm to the wheelbase (up to 1385mm) to accommodate a revised, higher profile front tyre size; now 120/70 ZR17. Also at the front the 2005 bike gained new 41mm usd forks (in place of the previous 43mm teles), again fully adjustable, with the addition of radially mounted front calipers.

To ride, an ’03-’05 R6 should feel sharp, with light, accurate steering and an eagerness to turn and respond positively to any input given. The bikes’ on-track success highlights the package’s effectiveness as a top level supersport machine. Above all an R6 should be fun to ride, both because of its rapid, rev-hungry engine, and willing chassis.

2003-2006 Yamaha YZF-R6 - What to look for

 Gearbox
The motor’s weak spot. The R6 is a hooligan’s dream, so it’s no surprise that many owners love a wheelie or two. Badly executed monos leave their mark on the transmission – second gear in particular – that, when damaged, will struggle to stay engaged, especially under power. Insist on a test ride and try each gear under load to ensure the engagement dogs are still up to the job.

Crash damage
These Yamahas are now 25 years-plus in age, so there’s a high likelihood that any 2003-2005 R6 you view has been dropped, pranged, or put back on the road after a spill. This isn’t necessarily an issue, if the repair work has been done properly, but anything bodged back together could be an issue. Look for scratches and dents on the frame, swingarm and forks, badly fitting body panels, scuffed controls, and out of line wheels. A £10 HPI check will show if a bike’s been written off, then repaired too; CAT N indicate superficial damage – non-structural.

Front tyre
The stock fitment is a 120/60 ZR17. Don’t be tempted to fit a 120/70 ZR17 because it’d higher profile may cause the tyre to rub on the mudguard. The steering won’t feel as natural or light, either, so stock sizes are best. Most tyre manufacturers offer sticky road and track options in the R6’s sizes – the rear is 180/55 ZR17, so choose a compound that best suits you riding type.

YISS immobiliser
The 2003 R6 was the first model to feature Yamaha’s own inbuilt security system, but it’s important to ensure that the bike you buy comes with the red coloured master key. Without it you won’t be able to get any spares cut. Instead you’ll have to replace the ECU, ignition barrel, and all locks, and that won’t be cheap.

Rossi rep
Sold only in 2005 as a limited edition (only 2500 were built). To VR fans in particular the YZF-R46 has an added draw over the standard bike. Genuine Rossi reps should come with the obligatory sun and moon paint scheme, as well as a Termignoni end can and a plaque on the top yoke stating that it’s a pukka special edition model. Yamaha charged an extra £600 when new. On the used market they can make a few hundred quid more than a stock R6 – to VR fans, obviously…

 Coils
If your R6 is misfiring, it’s likely that the ignition coils are beginning to break down. Yamaha discovered that the early batches of Nippon Denso coils were susceptible to water ingress, causing them to fail, so replacements from another manufacturer are the recommended upgrade. By now most if not all rogue coils should have been discovered and replaced.

 Throttle Position Sensor
Another electrical component that can cause issue is the TPS. Signs of potential trouble include difficulty starting, woeful fuel consumption and under par performance. A new replacement is around £120.

2003-2006 Yamaha YZF-R6 - Rivals

2003 Honda CBR600RR - First of the RR model CBRs. Easy and accurate handling, a strong motor and build quality beyond what had previously been expected of the 600 class kept the CBR600RR at the head of the Supersport class. Popular with racers at the time and trackdayers since so check for evidence of track spills and abuse. Still looks fabulous, and Honda continue to sell an updated version of this model.

2003 Kawasaki ZX-6R 636 - Kawasaki’s 636cc ZX benefits from the extra midrange bulge afforded it by the bike’s additional capacity, particularly on the road. The chassis is as sharp – if not sharper – than its competitors, however, making the 2003 6R a proper sports bike fanatics’ dream. Small in stature and tight on terms of ergonomics so check that the fit before you buy. Build quality can be iffy in places too, so condition is everything.

2003 Suzuki GSX-R600 - K3 era GSX-R uses the same frame and dimensions as its 750 stablemate, but with cruder forks, shock and swingarm. A proper little rev box and an engaging ride when in good nick, but many used examples suffer from dubious levels of prior ownership. These Suzukis can look secondhand and ride poorly if not kept tip-top. The standard brakes are awful too – upgrading to braided lines or a 750 front end will help.

Honda CBR600RR, 2003 | Approx Price: £1800-£4000

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Power/Torque

117bhp / 50.7lb-ft

Weight

174kg

Kawasaki ZX-6R, 2003 | Approx Price: £1700-£3800

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Power/Torque

118bhp / 50.7lb-ft

Weight

174kg

Suzuki GSX-R600, 2003 | Approx Price: £1700-£3800

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Power/Torque

115bhp / 50.9lb-ft

Weight

163kg

2003-2006 Yamaha YZF-R6- Verdict

The second generation R6 strikes an excellent balance between performance and day-to-day usability. The riding position is aggressive without being painful, while the performance – although mainly beyond five figures – is still linear and smooth enough to make everyday road riding possible. Later YZF-R6s are more extreme, lacking any notion of practicality at the expense of outright performance. And it’s because of this – and affordability – that the second generation of Yamaha’s middleweight superbike remains a popular choice on the used market.

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2003-2006 Yamaha YZF-R6 - Technical Specification