1979 Yamaha YZR500

1979 Yamaha YZR500 by Paul Adams


Tamiya’s first foray into the manufacturer of motorcycle kits began way back in 1980 with their first release of kit number 14001 – Kenny Roberts championship winning yellow and black YZR500 Yamaha grand prix bike. Clearly very proud of their achievement, Yamaha assisted Tamiya in producing a superb, reasonably detailed replica of the bike, though by today’s standards it has begun to show its age. The kit was an instant success and Tamiya followed up this release with a kit that included a figure in typical knee-on-the-ground Roberts pose.
Unlike today though, at the time, they didn’t release the kit in different guises until the Barry Sheene version was issued just a few years back which featured a few parts to update it to the non-factory 1981 spec bike Barry ran unsuccessfully that year. Around the same time Dexter Models release a number of decal sheets to help modellers build different riders versions including the Venezuelan rider Johnny Cecotto (pronounced che-cot-toe). In the late seventies Cecotto was the factory rider for Yamaha Europe and ran a similar scheme to the US Yamaha backed bike of Roberts, but in red and white. This scheme is considered to be the factory paint scheme as it was the colours Yamaha used for arguably the greatest ever rider, Giacomo Agostini.  [1]
So history lesson over-with and keen to build something less taxing then the Assen Yamaha, this bike would be my next choice to add further to my racing bike collection.
My choice of kit would be the Barry Sheene Akai kit as it’s moulded in white making the painting of the livery easier. The original kits were moulded in yellow! The first thing that strikes you is the simplicity of the kit. The parts count is visually less, with parts like the top yoke and handlebars all cast in one piece. Today’s MotoGP kits have separate top yoke, clips and grips. The standard theme for building these early kits is all evident though with a four piece frame, two piece swingarm, a two part fairing that goes together very well, but it means the modeller fits the front wheel after the fairing is attached. The fuel tank has no bottom to it and the windscreen is very thick. Whilst the white sprues are up to modern standards the black sprue is a real shocker with a multitude of seams, sink marks and flash to deal with. One interesting thing to note is the early kits had the forks mould with a chrome finish – the reissue kits have these parts in white. A lot of time saved, by not having to strip the gaudy finish off here! [2,3]

[2] [3]

I always start a bike model by cleaning up, constructing and where appropriate, paint the main parts of the bike, those being the frame, swingarm, engine, wheels and body or fairing parts.
I began construction with the fairing, tank and seat. These parts were cleaned up and glued together using my usual method of superglue and zip kicker. This filled the gaps along the seams and provided much needed extra strength as the fairing will need to be widened slightly to get it on over the engine. After sanding back with 400 grit paper the seams were finessed with 800 and 1500 grits. I filled in the mounting hole at front of the fairing and carried this on to the side holes too. This was done using some plastic rod and more super glue to blend it all together. I then drilled out the reverse side so that the shortened mounting lugs would sit nicely in the holes. When finished, the outer surface will be dressed with a photo-etch nut as will the fairing nose. [4,5]

[4] [5]

The building of the frame was held up by the endless cleaning up to do around the small details. This plastic seemed very soft so it was easy going with 1000 and 1500 grit papers to avoid any deep marks with the coarser grits. The frame was glued together but still felt fragile. The two outriggers that support the seat were ridiculously thin and inevitably I broke these twice during handling. I trimmed a few mould bolt heads off to be replaced with etch items later. A coat of primer, two coats of zero black and two of clear offered a glossy finish, but not quite what I was after. The real thing has a glossy look to it, but in this scale it looked toy like. I polished the paint with 600 grit Mr Hobby compound, and came up with an in-scale sheen.  I discovered subsequently that I fitted the clock pod support upside down – either that or the frame is upside-down!!  I’ll sort this out soon!! [6]
The swingarm assembly posed a number of problems. Aside from being the worst part of the kit, the instructions call for the arm to be painted and assembled around the finished rear wheel which would leave large visible seams and a poor finish. After testing the whole assembly with the wheel, I decided to simply shorten the mounting boss on one side which would enable me to slide the wheel and tyre in without resorting to separating the arm too much and risk breaking the thing apart…which I managed to do during trials! I spent many hours filling and sanding this part to get it in reasonable shape – but failed I think with the monoshock  – it is way too simplified to be convincing and desperately needs a nice machined upgrade. As it’ll be hidden beneath the tank, it shouldn’t look too bad once complete. The arm was sprayed with Alclad aluminium over grey primer, the shock was done with Duraluminium. The picture shows the ends of the arm masked up for further panting. Once that’s done I’ll apply some shading around the joints using Humbrol Steel. [7] 

[6] [7]

The engine is a simple affair but with multiple parts in its construction, some thought has to be used to get it all lined up nicely so it fits in the frame correctly. Once that was done I started with the filler as there were gaps all over the place. I used Tamiya grey putty which was allowed to cure for 24 hours. Halfords trusty grey plastic primer was sprayed on left to harden off while I considered what paints to use. My Pitwalk reference book shows the engine with three colours or tones of grey. I use Alclad paints for the steel, dark aluminium and bright aluminium finishes. In hindsight the steel crankcase is a little light, but it looks fairly convincing. The picture shows the engine in its raw state, with still the clutch and some minor painting to complete. [8]  

[8] [9]

The wheels were another victim of the black plastic sprue and so more Halfords sand papers were consumed in the clean up. The seams were more like steps they were so prominent! I primed with grey primer again, but I used zero black as an undercoat for Tamiya’s TS21. A rare event for me this, but the Tamiya gold yields a very realistic 1970’s look to the wheels. [9] 
Lastly this month is the painting of the bodywork. After cleaning up I primed with Halfords plastic white primer and set everything aside for a couple of days. Frustratingly I always find some blemishes that need’s attention as it’s difficult to spot all of them without paint. More primer was applied and gently sanded back with 1500 grit wet and dry paper. The main colour was simple to obtain with Zero pure white shot through my Iwata CR Revolution airbrush set at around 25psi. Three good coats of clear followed, and with a good few days of drying behind it was swiftly onto polishing.  I’ve begun using a simplified system for this process of late. I used 2400 grit Micromesh cloth soaked in a water/washing up liquid mix and gently use this all over the clear to achieve a flat look. If there are any glossy spots it means the surface isn’t level and you need it level to obtain the mirror like finish seen on real vehicles. Next up is Mr Hobby 600 compound which brings back the shine quickly. I finished with Mer car polish to get the effect you see in the pictures.
 With the clear on I could get on with the task of decaling. The decals are from Aussie manufacturer Dexter Models, and as I hadn’t used them before caused me some concerns over how they would perform. I thought I’d start the hard way and put on the fairing nose yellow decal. I immediately ran into problems as my softening solution didn’t work. Thinking it was out of date, I used a newer bottle only to find the same thing. I concluded that Microsol was of no use and fortunately I had a bottle of Daco Medium decal set which was just about strong enough to soften the thick decal and after 2 hours it was on!! With the nose decal on, I could apply the thin black edging lines and move onto the distinctive red stripes on the sides. I found these to be very brittle, so great care was need when moving them into position. Despite this some areas did crack, but some Zero red paint hid most of the tiny gaps.  I spent a good few days on the decaling and I allow a week for them to fully dry before clearing. The decals were difficult but not impossible to use. The associate sponsor’s decal are a little undersized but overall the scheme looks about right.

I used the aforementioned technique to clear and polisho over the decals and I was particularly pleased with the end result. [10,11,12]


After painting the swingarm in Alcad Aluminium, the ends were masked up ready for further painting and shading. The moulded-in chain adjusters are nothing to shout about but will suffice for this out of the box build. They were painted with Humbrol gun metal and then shaded using Humbrol steel. I also added further shading to various areas of the arm and shock body, which adds some interest to an otherwise bland paint job.  I picked this technique up from fellow bike builder Andy Wright, who uses it to great effect on his bikes that appear in TMMI. I then added the spring and retaining clip to the shock and it was complete. The chain and sprocket were painted up using Alcad steel and Humbrol steel. A wash with Tamiya smoke and a little drybrushing blended everything in nicely.

[13] [14]

I carried out some detail painting to the water coolant feeds, painted the very basic looking clutch and added a wash to it all using Humbrol gun metal. I then set about painting the carburettors. These were moulded in the awful black plastic and took a disproportionate amount of time to clean up, given their size. I used Alclad paints to achieve the metal finishes and a mix of Tamiya acylics for the ‘cap’. Once attached, they were given a wash with Promodeller ‘dirt’, which was blended and rubbed off for a nice used finish. I highlighted some areas with drybrushing with Humbrol flat aluminium and a wide brush. The carbs were also treated to some fine steel wire and cables to replicate the throttle cables.  Here is everything installed along with the swingarm  [13, 14,15]

[15] [16]

The wheels had been painted for sometime, so it was onto the brake discs to complete them. I’ve never been satisfied with my attempts to replicate a steel disc face, so I had a good look around to find some inspiration. The face always looks shiny, almost like a polished steel effect provided by Alclad. Using this however meant painting the faces with gloss black and eliminating some of the fine detail. Andy Wright once again had an interesting approach and using my Pitwalk reference book too, I sprayed the discs with grey primer and loaded the airbrush with Humbrol Metalcote Steel and airbrushed the centre of each one which was then masked off. I then polished the primer coat on the disc face using 3000 grit micromesh and airbrushed Alclad aluminium. After further masking to the inner mounting ring of the disc and with the disc mounted on a cocktail stick and secured with a little liquid masking fluid,  I remounted the disc onto my hobby drill. Loading the airbrush once more with the Metalcote steel, I spun the disc and faded two lines of steel on the face, fading the first from the centre and the second from the outer edge of the disc. I repeated the same on the inside face too. I allowed the steel to dry for 30 minutes and then powered up the drill once more and buffed the steel paint with a soft duster. The resultant finish outweighs anything I’ve achieved before and looks very effective once the disc was mounted on the wheel. I repeated the same process for the rear disc too. [16]

The forks were cleaned up and primered before being given a coat of Alclad Duraluminium. The calipers were airbrushed Humbrol Metalcote Gunmetal and gently polished using a soft brush offering a natural highlight finish. I used Tamiya smoke to help give the forks some added depth. I noticed that the forks are inaccurate when comparing the kit with my references. I have yet to see a 1987-80 Yamaha with this type calliper bracket and additions to the fork legs. [17]
Finally for this month the handlebar assembly is done with the exception of some photo-etch boltheads. The lack of sophistication on early machines really shows here.   The whole thing was given a coat a Zero black and it was simply a case of masking off the correct areas before Duraluminium was used again to match the forks. Humbrol flat black was thinned slightly and brush painted on the grips, followed up with some minor washing to the whole thing. [18] 

[17] [18]

The rear wheel was ready to be added and due to the earlier trimming of the mounting boss it went in fairly easily. The rear caliper comes in two halves and the instructions suggest gluing this together once the wheel is on.


With the prospect of a visible seam I glue both parts and ran some more glue along the seam and hit it with Zip Kicker to dry it off quickly. This was a risky strategy as one slip of glue would have meant a repainting session for sure. I then carefully sanded the join, taking care not to sand anything surrounding it. After some repeat sessions the caliper looked like a one piece item. I hand painted the caliper with Humbrol Gunmetal Metalcote and gently drybrushed the paint with a brush to generate some natural highlights. [19] 


I completed the forks by adding some chrome bare metal foil (BMF) to the fork tubes – while this effect will never match a nice pair of real polish tubes, it certainly looks the part when assembled with the yokes. Next time I attempt this era of bike, I might just try and replace the tubes with some aluminium tubing. I decided to add a new product to the calipers from Tuner Model Factory (T2m). They have released some beautifully machined brake parts that represent the hose fittings superbly. Each fitting requires three parts, a threaded fixing bolt, a ring fastener and flange fitting. All of these tiny items have internal and external threads and have to be screwed together! After some trial and error I eventually got one on each of the front callipers and one on the rear. I used some Top Studio heat shrink tubing for the brake lines. The parts add some serious realism to a much neglected area. T2m have also done fittings to replicate modern bikes too, so I look forward to using these again in the future. With the forks done I was able to assemble them with the front wheel, mudguard and yokes. [20]

[21] [22]

With painted parts piling up, some more assembly was needed. I added the radiator and its water hosing using Tamiya’s soft black tubing and replicated the fasteners with BMF. The ignition coils were painted with Alclad and Humbrol paints and carefully glued in place. I could then add the HT leads to the plugs. The exhausts went on next and I must confess some confusion with their placement lead to me trimming some plastic away unnecessarily from one pipe. I realised my mistake after a coffee break – a quick shot of gunmetal from the airbrush and fortunately my error will go unnoticed on the completed model! Tamiya’s lack of experience with bikes shows here as the engineering isn’t as good a today’s kits. One of the pipes sits someway forward from the others but fouls the fairing. Further adjustment was need to the pipe that snakes through the frame as it fouled the seat with the silencer on. The fit into the cylinder heads is nothing to clever either – something to look at on my Kenny Roberts version. I then glued on the footrests which were painted with Alclad Duraluminium and Steel finishes. A wash of Tamiya smoke enhanced the boltheads.  [21]   
A test fit of the forks showed that everything lined up nicely before final assembly. The fairing will need to be fitted first before the forks can be glued in place. [22]


My least favourite part of the build beckoned – painting the insides of the body parts. I painstakingly masked off the edges with thin Tamiya tape cut from an 18 mm piece and used Mig Productions excellent masking fluid to quickly cover the larger areas. Bluetak covered the larger holes and prevent any leakage from overspray. I airbrushed Zero Jet black on in two coats for a slightly scruffy look reminiscent of bikes of the period. Much to my relief after unmasking, the result was satisfactory. A quick polish up with Tamiya wax left the parts waiting to be fitted.[23]

The silencers require carbon decaling before that can be weathered and fitted. The kit does supply decals for this purpose, but they are incorrect in colour and weave according to my references. After trying two of the kit decals out, these were discarded


in favour of carbon decal sheet from Modellers, now sadly no longer available. I trimmed out four pieces using the Tamiya decals as a guide. As the kit decals have the metal fasteners printed on them, I had to use photo-etch items from Top Studio to replicate them. I applied some Johnsons Klear to even things out a little and did some shading via the airbrush with Humbrol Gunmetal. The overall result was much improved over the out of the box option. [24] 

With the bench clear of bike parts I painted up the last few pieces, including the clock pod which was finished simply with Tamiya dark grey and Zero black for the clock surrounds. After applying the decals some clear varnish was flowed over the top of them to replicate the glass. [25]  


The fairing was attached and secured with white glue but not before I shaved a little off of the offending exhaust that fouled the insides. The forks could then be attached by simply screwing the top tree in place with a 25mm screw. No glue required! The brake lines were brought up from the calipers and fixed into place. This was a fiddly task made worse by the having the fairing on already. I then glued the upper fairing supports in place and slotted these into the corresponding holes on the fairing, thus providing a very secure fitment. The fuel tank could simply be push onto the frame as the fit was tight. I added the fuel cap and ran an overflow tube from the tank to dangle just past the upper supports.   
The rear seat was the last part to go on. I had previously broken the seat outriggers twice during assembly and even after pinning them, they broke once more. I decided to strengthen the arrangement by adding a small piece of plastic card across the frame in the hope that it would offer more support. It broke again, this time a little too late to do much about it. With a scruffy repair affected, I was glad to glue the seat into place. The seat pad was sprayed with Tamiya XF dark grey. Finally photo-etch bolt-heads were added to the fairing and various areas on the frame and swingarm.

[26] [27]

Tamiya’s first bike kit was a challenge and it’s clear that they have vastly improved the engineering on their bike kits since this release. With the exception of the incorrect frame tubing (it should be round, not square) it does however provide a great starting point for a detailed replica. I’ve two more of these to build, in Kenny Roberts and Barry Sheene paint schemes.  This build will serve me well when I come to do them. [8, 9, 10]


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