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Last month we looked at the various top end arrive and drive options. This month we’ve moved on to owner-driver racing but we’re looking at classes where people have had the vision to try and make racing easier for busy drivers.
The BMB HAT 125 is a relatively new engine from Birel’s BMB engine company, and is imported and supported by Andy Cox Racing. It is a TAG engine in so far as it has a starter motor, a balance shaft and centrifugal clutch. It has a vertically mounted reed valve. The overall concept has more in common with 100cc engines of old in that the water pump is externally driven from the axle and there is no power valve. The external water pump is a result of the crankcase being a carry over from the Easykart air cooled engine more of which later.
On venturing out on to the track at PF my first impressions of the engine were good. A very generous helping of mid RPM torque caught me out on cold tyres and I went sideways immediately after leaving the dummy grid. Straight away I made a mental note to take my time getting the tyres up to temperature. The lack of a power valve on this engine was not holding it back in terms of mid range punch and its pretty clear that a good job has been made of matching the pipe design to the engine and its fixed ignition system.
At very low RPM there is not very much torque but this is by no means a hindrance as when the engine comes on pipe it absolutely flies! Correct gearing and a moderate amount of driving skill is all it takes to keep things cooking in the power band. I drove a couple of pre-production engines that differed slightly in terms of delivery of power at mid RPM. Both engines had very similar high rpm characteristics though which may mean that these box standard engines had slightly different jet settings on the Tryton carburettor. A very good characteristic of engines like the KGP that have a butterfly carb is that there is no hesitation when you just stamp on the throttle as there can often be with float bowl slide carbs unless they are very well set up.
The power delivery softens as you reach the high RPM and the transition is gradual with the engine revving cleanly up to its soft rev limit of approximately 16500 rpm. This engine will surprise all but those Rotax racers with very well sorted engines in terms of its mid RPM power delivery but the top end power on the KGP is lacking that last push you get from a power-valved Max. In terms of driveability and adjustment of carburation the KGP is excellent, sharing its power delivery characteristics with the 100cc engines we last saw in 2007, particularly the Formula ICA engines, due to the similarity in timing of the exhaust port and three transfer ports.
The carb used on the engine has a 26mm choke and is typical of butterfly style carbs that have been sucessfully used in karting for decades. It has two screw type adjustment needles for the low and high jets making it easily adjustable. Simples!
The engine itself is a model of simplicity compared to the KF engines with their multiple electrickery boxes and plugs. The BMB has one loom with a single plug at each end that connects the ignition stator and starter on the engine to the CPU, a switch and button, an LED and a relay mounted under the nassau panel. Starting procedure is carried out by flicking on an ignition switch and pressing the starter button. Ignition on is indicated by a red LED.
One feature in particular that many may welcome is that the engine is not sealed in any way and a top end inspection and service can be easily carried out by those inclined to do so. Pistons are said by the importer to require changing after 10 hours use however anybody who races two stroke engines will tell you that a ring change at half of the pistons recommended life will bring some noticeable power gains. Many others will definitely say that while you are at it you may as well pop a new piston in there too if you can afford it.
The bottom end is reported to need a rebuild at 20 hours of use but there is no doubt in my mind that those who can, will replace bearings a lot sooner than that. Carrying out this work yourself if you are a club racer who has (or is keen to learn) some mechanical ability is a very cheap and satisfying way to go racing. After an investment has been made in the right tools (available from Dartford Karting) an engine rebuild can be done at cost by yourself for half what a professional will charge however the expertise in putting together a winning engine takes some time to learn and that is what you pay for with the pros, many of who will have thousands of hours of dyno time under their belts too. Rebuilding and trueing a crank can be quite challenging too.
However, if you’re not up for that, any two stroke specialist can rebuild it for you. GFR and Ogden have shown a lot of faith in the new class by buying engines to hire out and they also offer rebuilding and tuning services. Look out for special offers if you hire an engine and then want to buy it.
At this time the technical rules are not finalised but it is fairly definite that moderate tuning will be allowed to be carried out on the barrels and engines in general. The cylinder head volume will be fixed at 10cc with a 1mm minimum squish. The exhaust port timing must not exceed 180 degrees duration. There will also not be any changes allowed to the exhaust pipe although there may not be any major advantages to be had in changing any of those things because it is not possible to alter the ignition timing on the BMB to suit any radical tuning. In any case the scrutineers will be on the look out for any illegal head volumes, off-set crank keys and exhaust spacers.
Slick tyres for the class are to be the Vega XH and I was very impressed with the high levels of grip given by them. I tried two sets, one set with over 50 laps on them and another set that were less than 15 laps old. After the initial short-lived advantage naturally given by brand new tires ended they appeared to be very hard wearing with very good consistency as they wore on. Others present at the test reported the same and went so far as to say the tyres showed very little drop off in performance up to 200 laps. Overall I could not fault the tyre performance for the short period I spent on them.
It is still early days yet for the KGP engine in the UK and like all new products there are teething problems. The starter motor has been very unreliable on the pre-production engines although it is being changed for another make of motor along with an o-ringed support that will be installed on engines available for purchase soon. The clutch on one of the pre-production engines gave us some trouble towards the end of the day and a main bearing developed a tight spot although this was discovered before any major damage occured. These engines were used on a number of days as demonstrators, had done many hours prior to this track test and to be fair were due a rebuild.
Those people who have water pumps and radiators from 100cc engines may be able to use them on the KGP. Any Birel Free Line radiators are eligible to be used as are the standard radiators used on the Formula Blue engines. There are other makes of suitable radiators on the market however the importer needs to be contacted as to whether these other rads will be allowed when the series kicks off in 2011.
The KGP series certainly looks promising and early impressions from many who have tried the engines has been quite favourable. The concept behind it is clearly to bring kart engines back to their roots while still retaining the added luxuries that the various TAG engines have brought to the sport in the last decade, but without the relative complexity of the KF engines. It has the potential to change the face of karting in the UK much in the way the Rotax FR125 did more than a decade ago and the TKM BT82 before that. The real test for the KGP idea will be whether it takes off at club level, something the KF engines have failed to do, so ACR has set up an incentive package for clubs and competitors.
Easykart has been around for a few years now and is growing in popularity. The series was also brought to the UK by Birel importer Andy Cox and the championship is organised by Club 100. The Easykart concept is aimed squarely at people who want to race and own their karts and take part in a competitive championship run under MSA regulations and all on a budget. There are 4 classes – 60cc Cadet, 100cc junior and 125cc senior heavy and light. As the name suggests it it aimed at people who want to own an easy to run kart that is cheap to race. For a reasonable price Easykart offer a preparation and storage/transport option for those without the time or space to work on their own karts.
To get a good idea of what it is like to race in Easykart we interviewed recent new entrant to the series, Mike Roots.
“I have raced for 15 years various karts such as Thunderkarts, Rotax Max, TKM, British University Karting Championship, Club100 and now Easykart. I came out of uni and did TKM on a budget, and although got good results I thought the money was having a too big impact on my life so decided to join Club 100. I loved Club 100 and won the heavyweight championship in my first year. I then bought an Easykart and did my first round at Whilton Mill in which I came 2nd. After a few months out, I am prepping for the start of 2011 season of Easykart and aiming at place in the World Finals.”
“The chassis on the Easykart is pretty balanced, is rewarding to drive on the limit but also challenging like any TKM or Rotax CIK chassis I have driven. They are not as wide on the front as a modern CIK chassis but the turn in is consistent and the chassis as flexible as needed whilst the rear grip is well balanced. The karts are adjustable with front ride height, front and rear width, Ackerman, tracking, seat position etc yet the axle, seat and rims are a set regulated part, meaning no changes can be made in terms of product stiffness or material characteristic, meaning less money and testing is required to find the perfect balance on the kart compared to your competition.”
“The engines are the best part of the class, proving great power delivery in all areas. Unlike a Rotax and TKM where the power levels out, the IAME keeps on pulling and has a great exhaust note. The power delivery at the bottom end is great, allowing even an inexperienced driver to get out of trouble. The power delivery is smooth throughout the rev range and results in very similar lap times to a Rotax Max. The engine has a good service interval, twinned with a reliable carburettor. The series allows you to change carburettor and exhaust but only allows for one engine per chassis, cutting costs massively. If you have engine problems at the track Andy Cox Racing will loan you an engine to use to eliminate the issue of being stuck without a spare engine.”
“The tyres are made by Vega, and we are not seeing the issues that Rotax has seen this year in seniors. They compound is pretty soft and we typically replace a set at each round like you would in any competitive formula in the world.
“The Easykart series is the best I have raced in, or been part of. It is not as professional as Euromax, but then that is not its aim as this is not the type of series which Andy Cox or JV (John Vigor) at Club 100 wants to create. It is not stuffy or aggressive and it is a lovely place for friends and family to spend time. Club 100 are the promoters of the series and are also an amazing bunch of people who go out of their way to keep the customers happy. It is very competitive and there is the opportunity for every entrant to race at the Easykart world championship.”
“The racing also benefits from the minimal amount of set up that can be made to the karts such as axles, seats, wheels as this means you don’t have to spend £100s buying different seats and wheels and then end up spending money going testing. If you can drive and put a kart on the grid which is reliable, you can then copy the set up of the quickest driver as nothing is hidden, then only have yourself to blame if you are not as quick. This is unlike most other MSA classes where there is an endless amount of set-up changes you can make. This means testing days can be dramatically reduced, saving again on money throughout the year.”
“The cost of racing in Easykart is thought to be expensive for people who have only ever done Club 100, but drivers in the Easykart paddock who have raced in other MSA classes will acknowledge that the racing is comparatively cheap and that the cost of spares is not that expensive considering you only have to have one of each. There is no need for multiple axles of different grades in Easykart, and four different types of rims.”