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CIK-FIA fail to test new front bumper fairing correctly

Bosses of the CIK-FIA have admitted that they failed to test the new front bumper fairing for safety on uneven ground, away from the track.

The use of the fairing, which was introduced at the start of this year, was suspended last month following criticism from drivers and concern at the possibility of the bumper being ripped off and travelling under the kart.

“If the front fairing drops down onto the lower bar, it could, under certain circumstances, pass underneath the kart,” said CIK-FIA executive secretary Kay Oberheide. “This could only happen if the front of the kart is lifted upwards which is possible if a driver leaves the track and the kart crosses the verge or if the driver is off the track on a surface that is not flat, for example on grass. We should reproach ourselves for not having tested this system away from the usual track, on uneven ground. We have conducted a successful test in which we found a solution. I am confident that we will be able to implement this system for all international events at the beginning of May.”

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Track Test: 1978 Kestrel v 2005 Tonykart

then and now
1978 Kestrel v 2005 Tonykart

With the sport of karting celebrating its 50th birthday in 2006, it seemed an interesting exercise to pit a kart from the earlier days of the sport against its contemporary counterpart to see what progress has been made in kart development in recent decades. Using the driving services of Buckmore Park Kart Shop co-owner David Catt, a fully restored Sisley Kestrel/TKM FF99TT 100 National, circa 1978, and a 2005 Tonykart Venox UK Rotax MAX outfit were assembled at Buckmore Park for a back to back test session to establish what conclusions might be drawn from nearly 30 years of development. When the Kestrel kart was new, 100 National was the backbone of British karting, the Rotax MAX of its day.

Manufactured in large volumes by Bill Sisley’s Sisley Karting empire, some 2,500 Kestrels were sold during a ten year period from the early seventies into the eighties. While Johnny Herbert is of course the most notably successful driver who campaigned in one 3of these karts (to win the 1979 British Junior Championship) the Kestrel kart, over a ten year period, achieved ten outright British Championship wins campaigned by drivers such as Tim Davey, Tim Harvey, Lee Cranmer, Wayne Homer, Gary Prior, John and Richard Weatherly and Mark Tredwell among others. While the Kestrel is powered by a late ‘70s aircooled TKM FF99TT rotary valve producing approximately 19bhp and runs on rock hard, skinny Goodyear Blue Streak tyres, the Tonykart we used, kindly loaned by The Kart Shop, featured the hugely popular water-cooled Rotax FR125 MAX engine producing around 28bhp and running on Vega SL7 tyres. The karts look completely different. The Kestrel with no bodywork looks very narrow, especially on the skinny tyres, and while the Tonykart sports a 12mm disc and 50mm axle, these components on the older kart are exactly half these dimensions. The Tonykart subsequently looks a lot more aggressive with its liveried bodywork and fatter tyres. Out on the track, the Kestrel proved to be something of a surprise. Despite being some 3 seconds slower than the Tonykart, the whole experience was a lot more raw and exciting. You really felt part of the kart. Despite a lack of grip compared to the modern machinery, the Kestrel was superbly balanced and very predictable, especially on the downhill section of the circuit.

The Tonykart by comparison was very refined and because of the engine’s watercooling, more sophisticated exhaust and rev limiter, was a lot quieter. The kart drove with a precision that was missing in the Kestrel and was a lot easier to place on the track thanks to the superior grip. The engine is a completely different animal but provides strong performance through the entire rev 4range, the ‘70s motor being far more peaky with a narrower power band. David ran the older kart very rich and was also wary not to place too much stress on the brakes and the tyres but he reckoned by leaning the motor off, becoming more acquainted with the Kestrel and replacing the 25 year old tyres with something newer, it would easily be possible to get within a second of the modern kart’s times. The easiest way to contrast the experience would be to liken it to driving a 1973 Porsche 911 and a 2005 model. Both provide excellent fun and driving pleasure, the earlier example air-cooled and more crude but lighter and perhaps more sensational while the newer model does the same thing but with more finesse, precision and refinement. Whether that is to the detriment of the overall driving experience will always be up for debate.

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Track Testing: Tony ROK

Why a Tony ROK

After months of organization and setting up of the new “Track Testing” column, me and my photographer managed to visit the great Tony Kart Company and collect our Tony EVR ROK  engine kart. We have chosen this solution as it seems one of the easiest ways to start karting with a very performing chassis (Tony Racer EVR) and a very reliable TAG 125cc two-stroke engine (Vortex-Rok).

From 2003, the year of its establishment, until today the Rok Cup has won the trust of many fans in more than 35 countries all over the World. Rok has been a good novelty since it has been the first real single make solution directly followed by the company.  Start has been in Italy at first, then in Europe. After that it crossed the oceans and has arrived in South Africa, Asia and America. All the national champions, in every category, win the possibility to race in the Rok international Final, which is the CIK-FIA event closing the Rok season every year. The 280 best Rokkers coming from all over the World take part in this race and in the end we discover who the absolute champion in each category is: Rok, Super Rok, Junior Rok and Mini Rok.

Rok engines

Rok engines are a complete family of four different versions for the same number of classes: Mini Rok, Junior Rok, Rok and Super Rok. Mini Rok is the entry level for very young drivers. Vortex has developed two Mini Rok engines:
Mini Rok MINI 60 and Mini Rok BABY 60: the two versions differ from one another in carburettor and exhaust.

MINIROK BABY 60: supplied with carburettor of 14mm diameter and baby exhaust (reduced power), dedicated to the youngest; it is the entry level in the karting world.

MINIROK MINI 60: supplied with carburettor of 18mm diameter and mini exhaust; it is the second step in competitions, usually from 9 to 12 years old drivers.

 Rok range


We have decided to go for the ROK for our track testing since it is a good compromise between performance and reliability. To my opinion it probably represents best the aim of Vortex in creating the ROK World.

Junior ROK and ROK are based on the same engine except for the exhaust curve. Engine is a 125cc single-cylinder 2 stroke with reed valve admission in the crankcase. It is mixture lubricated and liquid-cooled with integrated water pump. It is offered with a digital ignition and an integrated electric starter, which uses a dedicated battery. It is provided with a balance shaft which reduces vibrations. A centrifugal dry clutch makes it possible to keep the engine on even when the kart is still.


Mini ROK Junior ROK ROK Super ROK
Bore (mm) 42.10 54 54 54
Stroke (mm) 43.00 54 54 54
Displacement (cm3) 60.00 123.95 123.95 123.95
Cooling Free air liquid liquid Liquid
Intake Piston port Reed valve (length 63.5 mm x height 25.5 mm) Reed valve (length 63.5 mm x height 25.5 mm) Reed valve (length 69.5 mm x height 25.5 mm)
Max torque (Nm) 19.6 at 10,000 19.6 at 10,000 20.2 at 11,500
Max power (HP) 10 at 10.300 19 at 11.500 29 at 10,500 36 at 12,500
Max revs 13,800 13,800 16,700
Carburettor 18 mm (14 mm for Baby ROK) Dell’Orto VHSH 30 mm Dell’Orto VHSH 30 mm Dell’Orto VHSH 30 mm
Fuel pump Dell’Orto Dell’Orto Dell’Orto Dell’Orto
Exhaust system With intake sylencer With integrated silencer and depower system With integrated silencer With integrated silencer
Drive Centrifugal Dry clutch Centrifugal Dry clutch Centrifugal Dry clutch Centrifugal Dry clutch
Lubrication 2-3% (Rok Lube or Elf 909 HTX) 3-4% (Rok Lube or Elf 909 HTX) 3-4% (Rok Lube or Elf 909 HTX) 6% (Rok Lube or Elf 909 HTX)
Weight 8kg 17,5kg 17,5kg 15 kg
Ignition system Electronic Selettra or PVL Electronic PVL Electronic PVL Electronic PVL
* Price (in Euro) – with carburettor, fuel pump, exhaust muffler, radiator & supports, thermostatic valve, cooling system pipes, on-off push-button panel, battery, battery support, electric plant, intake silencer. 1,950 + VAT 1,950 + VAT 2,400 + VAT

Prices are only indicative and subject to changes.


Super ROK is the ultimate evolution of the ROK engine by Vortex, conserving many of its important characteristics, but featuring an amount of innovations. Not changing the displacement of 125cc and the reed admission in the crankcase, the reed block is now bigger, and the carburettor is still a 30mm diameter VHSH by Dell’Orto. The new cylinder, always with liner, has a 5-transfers scavenging, and the 3-ports exhaust is provided with pneumatic power valve. The digital ignition has a different advance diagram; the exhaust plant is new in design with integrated silencer; the rotor of the centrifugal clutch is now monolithic.

The Chassis

RACER EVR Tony Kart freno BS7

Together with our Rok engine we have chosen one of the most performing and successful chassis from Tony, the RACER EVR. This chassis is available for both KF and KZ categories and represents the natural evolution of the EVXX the chassis that allowed Tony Kart to win all the most noble CIK-FIA competitions, including the World Championship, in these last years. The EVR is composed by a frame realized with Ø 30 mm tubes, which determine the kart to be more “free” when exiting corners. The Racing version is equipped with the new M4 bodywork and the new WTD (Wind Tunnel Design) stickers. The design of the new plastics resulted from several hours spent in the wind tunnel. The plastics have been optimized in order to reach an optimal aerodynamic penetration and to allow the air flow to invest the engine, the radiator and the brake systems in the best way during the races.

Homologation : CIK FIA 56/CH/14
Frame diameter : 30 mm
Wheelbase : 1050 mm
Stub Axles : OTK HST
Braking System : OTK BS5 – BS6 – BS7
Steering wheel : OTK rivestito in alcantara
Wheels : OTK MXP in Magnesio
Side Boxes : OTK M4
Seat : OTK a fondo piatto


This top chassis is provided with OTK magnesium accessories. The OTK brake systems BS6 and BS7 are still one of the most important features characterising both the former model and the new one. Front brakes are also included and will be tested to understand if and when these brakes are useful and performing for a driver.

Base setup for Tony EVR is neutral height front and rear and neutral camber and caster. Front torsion bar must be flat and rear bar eliminated. Rear carriage width will be to maximum limit at 140 cm and front carriage width will be adjusted with a small and a large spacer, equal to 2.5 cm additional width. Convergence must be 1 mm “open” at the front, so 0.5 mm per side. Seat will have stiffness bars o both sides, at least one, possibly two per side.

Rear axle stiffness is determined by five different materials indicated on the axles as HH, H, N, Q and U, starting from the stiffest to the softer. Base setup uses the N axle.

Prices of EVR chassis is 4,490 Euros VAT included, including front brakes, magnesium accessories and seat (price only indicative and subject to changes)

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We test the new BMB Kart Grand Prix

BMB came straight out of the traps at the start of the year, winning at their first attempt, the Winter Cup at Lonato. This new company is a collaboration between Birel and Carlo Boscolo. Boscolo is one of the famous dynasty of engine men that count Baroni, Corrona, Villa and Bossaglia among his rivals. Famous for his successful period with Ital Sistem, Boscolo has now turned his attention to the modern generation of TaG engines that now dominate the karting scene across the world.

Among the models on offer from BMB is the 125 HAT, which has many common features as found on the KF range of engines, but in a simplifi ed form. The engine is very neat and small, sitting very low on the chassis. Its compact design is thanks to careful positioning of the balance shaft below the crank. The engine has no exhaust valve but despite this is still expected to produce a solid 30 horsepower with a fl at and torquey power curve. Induction is through a vertical reed assembly into the front of the crankcase, which is fed by a Tryton HB27 two jet carburettor. At fi rst glance the engine looks like the last of the Formula A units which have all but disappeared now. The exhaust is a kissing cousin of the KF2 unit and produces a very similar noise and a bit, as this engine is prepared to rev to 16,500. The rev limiter actually comes in progressively from 15,500 so there is no point in chasing RPM for power, this unit is designed to deliver power across the range.


The clutch is unusual in that there is substantial initial slip, followed by a fairly sudden engagement. The design of the clutch is different to many in that it has leading shoes, which are apparently arranged in this way to enhance reliability. The internals of the engine are no great secret, a monobloc cylinder head with carefully controlled water fl ow is married to a beautifully fi nished cylinder of classic three port design, with a cast iron liner. Also reminiscent of classic 100cc design is the oval exhaust port with its two adjacent boosters.The bore and stroke is slightly over square at 54.28mm x 54.00mm. Another reason for the compact nature of the engine is that it employs an external water pump, with the radiator on the left side of the kart. It is a feature of modern chassis that there is plenty of room for this large radiator and still get some air to the brake. The senior KF classes are not so concerned about this issue as they have the benefi t of front brakes which take a lot of the load and heat off the rear.

Track Test
And now for the track test. Andy Cox had arranged to meet at PFI and fortunately the rain stayed away. Andy has formed a new company to promote the class with Vega importer Paul Deavin. Paul has had a very long relationship with Vega as well as many years experience at the top of 100cc racing. Two karts with new engines were available, one of which needed to be run in, Michael Simpson was also on hand and generously offered to do the fi rst running in session, I used to run in 100cc engines in three laps before boredom took over. Having mentioned this weakness to Andy, I was jocked off the job…perfect! Michael delivered me a run-in machine with carb jets set ready for action. The fi rst impression was of the excellent level of grip from the Vega XH tyres, this is the current generation of product and will deliver good levels of grip for at least 150 laps. The drop off in time against a new set proved to be less than 3 tenths. The wet tyre will be the current Vega W5 as used in international events. The kart handling was very neutral with these tyres and, although the butterfl y carburettor lends itself to being snapped open, and the pedal travel is very short, I believe it is actually better to feed the throttle in, which gives better drive off the corners. With this level of grip it is easy, and essential,
to brake late and hard into the corners, wait for the kart to settle before driving straight off the bend. Sliding the kart is a defi nite no. As the engines loosened up after running in it was possible to tighten the jets, just a little, with an instant improvement to the performance. As with most modern reed engines these were very sensitive to the slow speed setting. Within just 10 minutes on the slow jet, the engine went from gurgling rich to gasping for fuel. Because this is a relatively low revving, low compression engine, I imagine that it will be less seize sensitive than its 100cc forebears. However, good care must always be taken to keep the carburettor in good condition. Service intervals on the engine are expected to be at least 5 hours for the top end with a new piston assembly and 10 hours for the bottom end. The engine is no slouch in standard form and limited tuning will be allowed. I believe that a minimum exhaust duration of 180 degrees will be the principal restriction with a minimum head volume as well. All components must be of original manufacture including exhaust, carburettor, airbox and all other ancilliaries. The engines are to be delivered complete excluding water kit.

Rotax Champion Michael Simpson puts the outfit through its paces

Where to race
The BMB 125 HAT is being introduced internationally and may be known as Kart Grand Prix, although this is awaiting ratification from the FIA. Whatever the name may finally be, this is a quality product that may well appeal to KF refugees that can no longer stand the cost. It is bound to take a little while for the category to gain serious support but it will be racing here in the UK and across Europe in the coming months. At present there are plans to run a grid of Pro and Master drivers at the last round of the MSA Super 1 Series this year at PFI.

Birel and BMB importer Andy Cox and Vega importer Paul Deavin are the men behind the new class

The engine comes complete as described above for £1650.00 + VAT and will fit any modern international chassis. Most karts these days have radiator and pump mounting brackets, if not there are proprietory clamps on the market to take care of the problem.

More Information

• The official website for the new class is
• Graham Smith made a video from a Kart Grand Prix test day which you can see at
• I would like to thank Andy Cox, Paul Deavin, Michael Simpson and the team for a very enjoyable day.


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Track Test: Maranello RS7

1Maranello was a relatively new name on the karting block when Paul Ibbotson and his Botech racing team started to distribute it in the UK back in 2003. However the marque was already becoming well known through the expert exploits of its star driver Ben Hanley who has since gone on to make a name for himself in single seaters and has just recently been signed to the Renault Driver Development programme. While Ben raced for Maranello they shared international success in karting and became one of the few who were feared as a David among the Goliaths of the sport. Meanwhile out in the western fringes of commuterland Steve Green, a 2long term karting enthusiast, was considering an offer for his Audi dealerships, Aston Green. Along the way Steve had employed former British kart champion Fraser Sheader who had learnt the ropes through the various departments of a busy motor dealership. Gradually the foundations were being laid, deliberately I suspect, for the day when an opportunity arose for a concession to import a blue chip karting brand into the UK. Steve Green came to a deal to sell the Audi franchises and founded Heritage TVR in Henley-on-Thames.

Steve was soon able to entice Fraser to rejoin him in this new venture, in the knowledge that talks were in hand to take over the Maranello kart distribution from Paul Ibbotson. Paul was by now heavily involved with the management of Ben Hanley following his move into car racing and at the end of 2005 the take over was complete. Steve does go back some way in karting having been a Deavinsons customer back in the mid 1970s when he campaigned a Sprint/Parilla TT27 at Rye House and Tilbury. Steve also raced a Senior MAX much more recently and now enjoys running his son Elliot at club level competition. This enthusiastic involvement in the grass roots of the sport is not to be allowed to distract the new company from taking on the best at national and international level. Jason Parrott has been signed as official team driver and brings with him invaluable support from Peter Morling of the Gerald White Group. Peter is another passionate enthusiast for this sport of ours and races in Formula A himself. As a natural by-product of the agreement with Jason Parrott comes the most famous Fish Fryer in Peterborough himself, Tim, Jason’s father. 3Tim, a multiple European and World Champion in Superkarts now manages several drivers under the Tim Parrott Motorsport awning at most major events in the UK. Many if not all of these will in future be Maranello mounted. The feedback from the factory via Fraser and Jason will no doubt be invaluable.

Ian Hawkins from Hawksport is another team manager to throw his lot in with the Maranello brand. Darron Gibbs who was already running the talented Devon Modell on Maranello karts last year will continue to do so for 2006. In Northern Ireland Gordon Duncan will promote the brand and already has a number of the faster pedallers in the region on board. Jonny Maconald from Atlantic Racing will cover Scotland, Jonny has a near neighbour named Bryce Wilson who was seen and heard at the Autosport show. Bryce was a very fast and charismatic driver back in the 1970s and 80s and he is seriously talking about getting back in a kart for the good of his health! I saw that the wild man was a little older and wiser but when the conversation comes round to racing a far away look comes into the eyes and you know there is still the steel core of the ‘Braveheart’ running just below the surface. Jonny be careful! That therefore is the infrastructure surrounding this new venture, new in the sense that the company and the people are new but they are working with a well proven product. The first production model Maranello was known as the ‘30-32’ and this was followed by the RS1. There have been various evolutions since and the new homologated model is the RS7, also a ‘30-32’ construction. There is no shortage of expertise when fabricating the chassis as this work is entrusted to CRG and their customary quality of workmanship is immediately evident.

The 50mm axle is supported in three 80mm outside diameter bearings within cassette housings that are bolted to rings of steel

Gone are the days when MIG welding was the cheap and fast option and the welds on this frame are neat enough to be gas. I don’t know whether the factory are using robotic welders, if so they are very good indeed and if not then hats off to Guiseppi! The chassis design and development are down to Maranello and so is the outsourcing of accessories. I have to say that many do have the look of CRG about them and indeed this may have been the original source of many of the anodised alloy components. However many parts are now branded Maranello and I understand the factory is now interested in the autonomy of developing their own bespoke accessory range. The RS7 has removable front and rear torsion bars, the front one is often used and the rear one, seldom. There is also a removable fourth rail on the left side of the seat. This may come into its own as the weather and grip increases. The longitudinal rails of the RS7 are 30mm and the cross rails 32mm. This makes for a kart with lots of natural grip that remains easy to drive. For so many people the ability to go consistently fast is so much about confidence. The kingpin arrangement is thoroughly modern, 10mm bolts with four bearings in the stubs and an eight position castor/camber adjuster make this a very strong marketing point for the kart as it comes as standard. The stub axles are not the new fashioned 25mm shafts but a beefed up version of the 17mm variety.

A 1050mm wheelbase is bigger than most

The stub axle material is very hard indeed and I believe that this is the only area of the kart that features TIG welding. The axle is the usual 50mm that comes in a variety of stiffnesses and torsional rigidities. Until the driver can really extract the very best from himself and his equipment it is probably better to stick to the standard set-up before embarking on the axle-changing virus that seems to infect some camps from time to time. Maranello have chosen to develop their kart so that it will perform well under most conditions using the axle as supplied. It is supported in three 80mm outside diameter bearings within cassette housings. The axle has to be passed through the chassis as the bearing housings are bolted to a ring of steel with four bolts spread evenly around the housings. This I understand is one of the secrets of the success of this chassis and is a design feature that was first used by Wade Cunningham when he won the World Championships on a CRG in 2003. There are a couple of unusual elements to the Maranello kart. The chassis has a 1050mm wheelbase, the norm used to be 1040mm although some other manufacturers are also stretching them a bit. The brake is also a new design with a floating disc and a self-adjusting mechanism. I have to say that I was a little sceptical at first but the brake performed faultlessly on both chassis I tested, easy to feel and break the grip on the brake, what more do you need? For the track test we met up with the team at a now familiar haunt, Whilton Mill. The weather was fine if very cold but as it was during a prolonged dry spell in February, there was no hint of damp on the circuit.

Fraser (front) and Jason improved the set-up with every change and also improved George’s driving

We were there after the track had been extensively used for two days, by Club 100 on the Tuesday and for an open test day on the Wednesday. There were two almost new karts to be played with and my only concern was the seat. Stationary in the pits it all felt fine but I did have my concerns. As soon as I was out on the circuit having gathered a bit of speed I was slithering about the thing like a fat snake in a barrel. The boys fitted various bits of padding to try to get me under control with limited success until they introduced the ‘piece de resistance’ a substantial knoll between me and the petrol tank. Please allow your imagination a moment to picture this. An immediate improvement in lap times and smiles all round. Considering that we were running a well used set of tyres the MAX powered kart performed really well. It had plenty of grip without compromising the corner exit speed. The engine felt very strong indeed. We tried a logical set of changes to set-up and did nothing but go better and better. There was one other driver there, a potential customer, who also improved as the day went on. Fraser and Jason were not only very attentive from a mechanical point of view, they also sorted out a couple of corners for me, improving my driving to the tune of about 3/10ths of a second. Thanks lads, pity it’s about thirty years too late! We ran the MAX powered kart for the majority of the day, saving the other one with an ICA powerplant as a treat for last.

The brake is a new design with floating disc and self-adjusting mechanism

This was more than just a fun thing to do. Maranello also run this model kart in all the 100cc international races, so there is more than a little relevance to putting in a few laps with Parilla power. Simon Wright had kindly lent a new Reed-Top engine for us to try, Jason completed the running in and then it was my turn. Run, jump and it goes! No problem so far. Don’t spin or they will all be watching the first G.R. self start for some years. Luckily after just a few corners it all seemed quite easy, the kart in 100cc form was just as predictable and forgiving as it was with a MAX on board. I really enjoyed my few laps back in a 100cc kart again. What a shame that the end seems to be in sight for this great and historic form of racing. 100cc karting was described by Ayrton Senna as “the purest form of motorsport in the world”. I believe that a good day was had by all. The potential customer bought one so that cannot be bad. I had a great time thanks to Steve Green, Fraser Sheader and Jason Parrott. Not forgetting Peter Morling who turned up at exactly the right moment with the lunch! Since Maranello UK took over the franchise just before the International Kart Show in November they have sold in excess of thirty karts with more orders in the pipeline. Quite honestly I am not surprised.

The RS7 had plenty of grip without compromising corner exit speed
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Track Testing: LeCont tyres – a long run

The test kart

After out test of three different types of LeCont slick tires, with diverse IRHD hardness degrees, we have decided to long test them. We actually decided for the mid performing tires, the LH03, so to have the average performance of the LeCont range we had tested (on you can find the complete offer of tires by LeCont). We believe in fact that tires, especially for high performing but still leisure categories, like Rok, must give good performance, but most of all perform well and constantly for many laps. It is not sufficient to have high performance but quite fast decline, as we have somewhat experienced on Bridgestone tires.

Start of test

The rear right after 20 laps

The LH03 LeCont tires have 54 IRHD hardness degrees. We had already used the set of tires on our last track testing, running 20 laps with quite a constant behaviour. Best lap set at 61.09 sec with very poor track conditions and really no rubber and grip on the asphalt. Tire tread showing very little wear and just very small signs of tear of the rubber.

We reached the same Viterbo international track, three karts already running maybe giving the track a little more grip. Asphalt temperature measured equal to 52°C, extremely hot!  We started our test with exactly the same kart and setup as last month. Tire pressure set at 8.5 psi, except for the rear left tire that was the one working the most along curves as the track runs clockwise, which was set at 8.0 psi.


The front left after 20 laps

First session: 20+20 laps

The rear right after 60 laps

First session was ran for 20 laps with best performance at 60.17 sec at lap 9. So such lap time was already 0.83 sec faster then previous month testing, showing the track was nearly a second faster. All other laps more or less were ran at very similar times. Only difference was made in some laps when pushing extremely hard. In some occasions I made some small mistakes and on such track with low grip times went up immediately of 3-4 tenths of a second. After the first 20 laps tire surfaces looked pretty good, with just some tearing of the tread surface on rear left tire. The tread worn especially, as it often happens, in the internal part. Front tires also showed some very limited tear on the internal part of the tread, but wear was very even and limited. Considering low track grip and very high temperature of the asphalt, finally behaviour of the tires seemed to be excellent.

Second session: 40 + 20 laps

5We decided to go on with a second session. Another 20 laps to bring the long run to 60 laps total, considering the 20 laps already ran the first test one month prior to this test. The performance of the tires was incredibly good. Grip was immediately available and already the first lap gave good performance, maybe also thanks to the high asphalt temperature. This same aspect was also the reason for having the best lap performance always in the first 10 laps. This time best lap performance was set on lap 6 at 59.97 sec. Again a stop to check the tires. The look of the tread was incredibly good, with surface showing some grains indicating grip was sufficient, even if not at best level, and there was no real tearing or wear on the tires. The rubber was worn evenly on both front and rear tires, with just some tearing on the internal part of all four tires. This is something acceptable and normal on any kart tire.

Third session: 60 + 20 laps

6We were not happy yet and wanted to find the limit of the tires. They had to stop giving constant performance and loose some strength along the way. We set up the last session of the day. Another 20 laps just before the track closed at 18:00 o’clock. Well, mission failed! We ran another 5 laps and best lap time was 59.76 sec! Laps went on, no more fast laps as lap 5, but always around 60 sec. Tire wear seemed to be constant and similar to previous session. Finally LeCont LH03 tires seem to be a very good choice for any high performance leisure category. Of course LeCont in its range has more tires for even best lap performance. LH01 we tried one month ago surely gave nearly one second of lap time improvement on Viterbo track. Still the LH01 seemed to suffer a little more wear after the first 20 laps and maybe could be used for other categories. What is sure is that running 80 laps with a set of tires and still be able to obtain best lap performance at lap 65, is an extremely good result. It would mean having the possibility to do testing on Saturdays, qualifying and race with the same set of tires. This is what we can call great saving of money and great fun and possibility for more and more people to get close to karting in an easy and economical way.

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Track testing – First steps from seat positioning to running in

The frame is prepared for the seat
Measuring the distance between the rear axle and the top of the seat

The base setup of our Tony EVR was described last month. In general this is similar in all chassis, which means all chassis are set to work properly with neutral settings such as base caster and camber, 140cm rear width, neutral height front and rear, and with the front and rear bars mounted.

From these base settings it is then easier to fine tune the chassis with the possibility of decreasing or increasing angles, heights and widths. All this can only work though if weight on each tyre is well balanced. So at Tony we verified the mounting of the seat. From this point all setup changes will optimize the final balance for each track and asphalt condition/tyre compound and engine type. Only with the correct seat positioning we will be able to act correctly on the chassis setup.

Seat positioning

Four measurements are made to position the seat:

  • Distance between rear axle and top line of the seat back
  • Distance between the front line of the seat on both sides (under the legs, a sign is marked on both sides of the seat)
  • Distance from the front transversal tube of the chassis (just in front of our feet when we sit in the kart)
  • It will be positioned at height of a minimum of the thickness of three front sprockets on top of each other to a maximum of four.

Since I am not really the perfect kart driver physically speaking, as I am 183cm tall, my seat position was set so I could sit with my arms and my legs sufficiently comfortable so the seat was positioned some centimetres towards the rear of the chassis.

Measures for myself are the following with numbers in brackets as standard for shorter drivers:

  • Distance between rear axle and top line of seat back: 20.5cm (22cm)
  • Distance between front tube of chassis and front of the seat: right 63cm (66cm) and left 62.5cm (65.5cm)
Measuring the distance to the front of the frame

For all drivers seat height should be set with the equivalent thickness of three to four rear sprockets. The aim is generally to have the lowest possible height of the seat for a lower centre of gravity, but limit is the seat finally touching the asphalt or the kerbs around corners. So a choice must be made based on the kind of track the kart has to run on – smooth or bumpy, and whether you need to ride the kerbs or not.

These measures were set with a Tillett seat. Changing the seat type can change its shape and so all measures would automatically deviate from the basic measures.

Finally, especially for tall drivers, such measures can also be varied, still trying to keep weight distribution on the four wheels as it is. Variation often is needed, especially on fast tracks where tall drivers generate a large front area of impact with the wind and air. This causes high resistance to the movement of the chassis since Cd (aerodynamic coefficient) will increase as well. We will work on this in future Track Testing articles though, also verifying the effects on high speed and lap times.

Running in

I finally got to the track for the first impressions of the Tony EVR and Rok engine. My choice was to go on a Friday just before a race at the track. This choice is sometimes avoided by shy karters who prefer to practice at tracks that are not busy. The best choice is to practice where the real competition is, with rubber covering more and more the asphalt. This is the best way to understand our limits, potential, and chassis and engine behaviour in really challenging conditions.

The first steps when preparing your kart to go out on track for the first laps of the day:

  • Prepare the fuel mixture (petrol with 3-4% lubricating oil) and fill the fuel tank about half full
  • Cover the kart chain with a good quantity of chain grease. Grease must be of the right type, dense and sticky so it really sticks to the chain and does not fall off at high revs.
  • Before greasing the chain verify its tension is correct, which means position the engine on the chassis so the central part of the chain between front and rear sprocket can move up and down around one or two centimetres.
  • Inflate tyres and measure the pressure and adjust to the correct value. If you have just mounted tyres on wheels you first have to “blow” them so they adhere well on the wheels and then regulate the correct pressure. Make sure you reduce pressure of the tyres before using your pressure gauge for measurement. Too high pressure could damage the gauge resulting in consequent incorrect measures.
  • Try both rear and front brakes and see if the force on the brake pads is enough or if the brake pedal and hand brake have too much excursion, which means they have to be checked and regulated and most probably the brake oil has to be changed.
  • We should then check the correct ratio between the rear and front sprocket. An indicative ratio can be got fromk other karters or someone at the track. They might not give you the perfect answer and value, but it will be near the correct ratio.
The front brakes are checked

The first laps were to do the running in of the engine. Before starting the engine, check the fuel tube from tank to carburettor, it should be full of mixture. If not, when pressing the start button look to see the fuel moving along the tube to the carburettor. To help this, cover the air filter with your right hand and press the accelerator, to help the engine and carburettor “suck” the fuel from the tank. As soon as the fuel reaches the carburettor you will hear the engine start. Take your hand off the air filter and start accelerating and releasing accelerator until the engine is completely “on” and then go out on the track!

The first sensations driving the EVR and ROK are that there is a great balance of the chassis with great possibility to control the kart. The tyres used were quite worn and the track had medium grip. This led to a slow speed around the corners. The easy to use ROK engine has great torque but since it is limited to 13,800 max revs it is also used with long gear ratios which give it a good top speed, but difficulty in exiting corners. Better tyres and grip would have produced higher speed around corners and not problems in the exit.

In the next issue we will talk about tyres in testing and the effect of different types of tyres and the differences between using a worn out tyre and a new one. Also we will look at everything regarding pressures and the controls that can be done to understand if the tyre pressure is correct. Finally tyre compound, hardness, and tyre tread “reading” will give us good hints for the best performance of our kart.