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Every engine covered – TKM column

TKM offers a world leading choice for every driver – direct drive, clutch or TAG. Grahame Butterworth examines which might be best for you…

In TKM you really can have whatever you want – all you have to do is decide.  But it’s a question that needs careful consideration.

For a Junior stepping into a more powerful kart after a Cadet, then for my money a TAG (touch and go) motor is the way to go. That simple button to start and get the kart going makes it so much easier for Dad and youngster. And it is NOT slow as many have proved including pole position at the Maxxis TKM Festival.

Yes it costs £400 + vat more compared to a basic direct drive but you gain a lot of convenience. And if weight is no problem then it’s great for Extreme too. But there are two important points to bear in mind.

Al Paterson_0679

First a TAG set-up weighs about 4 kg more than a simple direct drive which is no problem if the driver is light but could be a problem if close to the class weight.

Second remember the TAG kart requires careful attention to preparation and service to ensure that the wiring is kept in good condition and that the battery is well looked after. It costs virtually nothing but fail to do that and you could have a techy problem.

Whether Junior or Senior if you want convenience but weight is an issue then go for the V clutch option with outboard starter. Costs less than TAG and weighs less but has the advantage of an engine which should still be running if you have a spin and gets you going again rapidly. And there’s less to go wrong. The long life V clutch is the same as used on the TAG and the hand held remote battery starter unit is very reliable.

Especially in Extreme there are many experienced drivers who like the simplicity of a direct drive. Less to go wrong, light and it can be run with a 9 tooth engine sprocket enabling smaller rear axle sprockets for short twisty tracks, whereas the other two models can only run with 10 tooth because of the clutch fitment.

The downside is getting the technique to get it started and starting yourself if you come off. That’s where the latest option – the EeziStart de-compression valve makes life so much easier.

EeziStart valve set in cylinder head

For around £29 + vat as an option on a new engine, it makes the kart so much easier to start yet adds virtually nothing to the weight. You can fit a new EeziStart head to an existing engine but it will cost about £178 + vat.

The valve is operated with one finger and takes the compression away so you can get the engine turning over easily. It then automatically snaps shut the moment the engine fires and away you go.

The EeziStart valve can be used on direct drive and clutch engines (but not TAG). Regardless of which engine you choose it makes perfect sense to pay the very few pounds extra to buy one with the EeziStart valve. Whatever format it will always makes the engine that much easier to start with no downsides.


Like this article? Then read more TKM columns here:

The real story behind TKM’s rise – TKM Column

TKM Extreme is booming once again


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TKM Insight

Should I buy a proven second hand old engine or a new one? Grahame Bu?erworth helps with the decision…

Ask around the paddock if you are looking at joining the class and you’ll get conflicting views on the way to go with an engine. Some will say old is best. Others new. Big help, eh?!

At first sight the TKM BT82 engine in use today is the same engine that was used when the class was first created many years ago. In fine detail however the engine has matured quite a lot, not to create extra performance but to help it withstand the incredibly hard life it has to endure within racing, increase life, and make every engine as microscopically close as possible.

Such continuous improvement of quality and production is what every manufacturer should look for in any product and that is what has happened on the TKM BT82 as each and every item is reviewed over the years.

So the cylinder liner ports in the barrels have for many years now been computer machined rather than cast, the small ends have been improved in specification, and a host of other minor but significant points all improved and aimed at making it stronger. Note  virtually all of those improved parts can be routinely upgraded on an older engine but you are not to know what an old unit has.

More recently the crank main bearings and oil seals have been increased in size to cope with the extra strain of a clutch, starter gear etc on the TAG engine – all of it running right across all the engine specs whether for direct drive or clutch or TAG.

None of this has actually increased performance as shown on a dyno graph but has helped keep down costs to you drivers by keeping expensive possible blow ups to a real minimum and extending rebuild times.

However somewhat illogically there are a number of engine builders out there who for their own reasons choose to claim that the latest engines are not as fast as older ones. They will tell you all sorts of reasons why – without any concrete facts to back that up.

Now I can guarantee you that Tal-Ko’s dyno does not lie and if you do the tests then old or new come up the same. This is also confirmed by track testing.

So while an old engine could be good, bear in mind you don’t know its history or the quality of rebuilding. On the other hand a new engine will be the strongest BT82 ever and comes with the knowledge that it is manufacturer guaranteed to be spot on. It will be stronger for longer.

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TKM Insight


The saga of droopy noses goes on but TKM takes a stand. Grahame Bu?tterworth explains…

Only a month ago it seemed like the droopy nose disaster had been averted with the CIK stopping
its use a?er serious doubts and accidents. But no sooner has that happened and another version pops up to be used.

Virtually no one in this country has even seen the latest version, yet already the MSA seem keen to make it mandatory for every karter next year. Will they never learn to wait and see what emerges before a commitment?

So let’s be clear and say that as class organisers we will not allow the use of such a system next year until we have properly had a chance to inspect it, see it in action and also see how practically it can be made to work in a club type racing situation.

Remember in the UK we also have different rear bumpers and in TKM we have push starting so all those things need to be considered before a decision is taken. We are not against progress if it is sensible. But we hate being asked to commit to unproven ideas that might adversely affect you – our drivers.

Let’s move on to something much more fun – the Maxxis TKM Festival at Kimbolton from August 7-9. This event has been running for nearly 20 years now and is incredibly well received by everyone who drives there – so much so that many return once a year to race there even when they have switched to another class.

This year will have two new twists. First, the same race meeting will be running the much coveted ‘O’ plates and it will be run in such a way that if you wish to you can enter for both an ‘O’ plate and in the traditional Festival/Elite section. You can do that with one kart or with two. But whatever the case it will mean you use two sets of tyres.

A further innovation this year is that the Festival section will also count for points in all three TKM club championships so that’s going to add to the competition. And the points will be scored in the normal format going to the drivers in each championship based on their results overall.

So lots to race for and with the usual bonuses of Friday testing and then two full days of racing with a pre-final and final. And all being covered by Motors TV which a special on the TKM club championships too.

Full regs, entry forms, tyre order forms are now on the websites at and www. Don’t miss out on the closing date – July 25.

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TKM Club Champs

TKMClub_JamieAndrews (4)The TKM Club Championships – backed by Karting Mag – have moved on at a pace since our last edition with two rounds in the Midlands, the first ever Southern and a second round in the North. The front runners are beginning to show.

In the Midlands, the area where the first trend se?ing championship was run back in 2012, there have been two rounds at Shenington and Kimbolton with some great racing! In Juniors at Shenington just when a magnificent scrap for the top places in the final was reaching its peak the red flag came out a?er one time leader Adam Sparrow was taken out by a low flying Joshua Sherriff. Both ended up in an ambulance. It left? last year’s champion Ma?tthew Taylor to take the win.

At Kimbolton in round two, it was Chris Whi?tton who took the win by a few inches from Adam Sparrow, with Ma?hew Taylor in third. On points that puts Taylor in the lead from Sparrow in second place. With Whi?on not doing the first round he is currently in 7th place but clearly a serious contender.

In Extreme at Shenington Matt?hew Allnut drove through from the fourth row of the grid to take a fine victory in a super close race from Gareth Haynes and Rowan Reed.

But at Kimbolton it was all change with Joe Stockford, who finished 8th at Shenny, taking a fine win. Jack Ransom finished second with Allnut in third. Harry Moore took second but was excluded for a non compliance. The points table shows Allnut first from Haynes and Reed with Stockford fourth.

Clubman have only done the first round at Shenington. Max Goldsmith took the flag in first place but to his horror was a whisker underweight and excluded. That le?ft Tom Longfield as winner of the final from Daniel Mense and last year’s series winner Jack Macaulay. On points Daniel Mense is in the lead from a large pack just a few points behind.

In the first ever round of Southern TKM club champs in Juniors it was Louis Beavan who put on a fine display to take pole position and first in the final. But he was chased hard by Lewis Ryder and Curtis Grainger who look like being a very close group for top places. In Extreme it was Will Fox who took the final from Lewis Round and Stephen Le Cocq. On points Lewis Round on top from Fox and Le Cocq.

Finally to the North where a?er round two at Rowrah Robbie Wozencro?ft has further put his stamp on the series with another win. Kristian Brierley, who got taken out in round one, was a close second having started from pole. Ethan Hammerton was third from Cameron Sharpe. So on points the order Wozencroft?, Brierley and Hammerton – just five points between them.

In Extreme, with first round winner Rob Wallace not competing, Lewis Main took pole position and the win putt?ing him six points clear of Sam Taylor with Joe Taylor in third. But Wallace will be back!

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TKM Insight

stock-tkm TKM have introduced a new component to help extend the life of older engines. Grahame Buerworth reveals the details. The big end crank-pin is a small component which takes on a massive job and if it fails can result in a nasty repair bill. Over the years the use of the TKM BT82 has seen its maximum rev usage continually climb way past the 15,000 originally recommended for the engine and that puts more and more strain on the pin. Years ago when my son and
I raced in the class I don’t
think we even saw 15,000
on the rev counter. Yet these days 16,500rpm is not at all uncommon, although certainly not recommended, and of course that puts huge extra strain and wear on the engine. Over the years steps have been taken to make the engine ever stronger – revised con-rod, larger main bearings, different big- end pin design/heat treatment, revised pistons etc.

None of it performance enhancing but all making it stand extra grief and strain without going bang. But as engines get older and older some areas can start to deteriorate, especially if they are not serviced correctly and have for example worn crank main bearing journals or crank-pins pressed in slightly out of true causing worn and damaged big- end pin fit holes in the cranks. You can end up with crank halves with slightly loose/damaged holes for the crank-pin, main bearings loose on worn journals and even bearings moving fractionally in their worn crankcase housings. In fact a whole variety of similar very minor issues can create an engine which is not running as smoothly as it should. The resulting problems and vibrations can be a big-end crank-pin disaster waiting to happen. And of course add in the fact that some people grossly over-rev the engine and you can have a recipe for failure. So especially to help owners of engines in that situation Tal-Ko have now produced a new heavy duty crank-pin which is solid with just partial drilled domed ends.

Now let’s be clear this is not intended to make you go quicker and will not be fied to new engines or the Performance+ fully optimised engines Tal-Ko prepare for top level racing. It is intended as a cure/band aid for those units probably past their  best which are still in use and which customers do not want to spend the extra money on parts like new crank halves. The new crank-pin is basically stronger and so will cope with that additional vibration and strain to give longer life. But do note it is effectively masking a problem, not curing it. The heavy duty crank-pins cost just a few pounds more than the standard item and are now available from Tal-Ko.

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TKM Insight – 2015 TKM Regulations

2015 TKM Regulations have been largely set in stone. The good news is that the changes for 2015 are aimed at making life easier for everyone

Whether driver, engine builder, or scrutineer the new rules should not cause concern for anyone. Arguably the most significant change centres on something that will affect many but hopefully in a positive way. It concerns the way that cylinder exhaust ports are checked and comes in the wake of the problems created by one rogue engine builder who this year decided to make up his own rules. If you are not an engine expert let me just say that the size and position of the exhaust ports is very important to the overall performance of the engine. Checking them has always been quite a detail and tricky job requiring specialist measuring tools. Tal-Ko have previously supplied a ‘no go’ gauge to test with but it was made to the maximum height size listed for the port at 21.15mm and the reality is no engine has ever been made with ports anything like that big. So to make life easier and more real world, there’s a two-step revision. First the maximum size port has been reduced to 21.06mm.


Second a new port height gauge has been made by Tal-Ko to check at that size. The important point is that in a normal standard engine that tool won’t go into the port but on an illegally modified engine it will drop in easily making it simple to identify. This new gauge will be supplied free to all relevant eligibility scrutineers and recognised engine builders. And if you want one for yourself then it will be available for £20 + vat. The old 21.15mm port height gauge will now become obsolete. The same will also be happening with the inlet port height dimension and I’ll bring you news on that next month. Note too in the new regulations Tal-Ko now has unprecedented powers to permanently mark any component that is illegal and cannot be made legal again. Another step towards killing anyone thinking of cheating, this will help ensure that parts don’t get sold on or raced that are not compliant with the regulations. Moving on you’ll also see in the regs new words added which follow up the clarification on rear bumpers and their fitting to make sure no-one tries to slip in another adjustable one.

Also clarified is the regulation that TAG engines must at all times be capable of being started on the button. The next issue is on Senior weight. A further weight/power band has been added, with a gold restrictor of 20.5mm and weight level: 139kg. This is to help lighter drivers (especially women) competing in the class without the need to carry excess lead. Minimum driver weight will be 44kg. To help reduce the problem of 50mm rear axle cracking you will also be allowed to make use of an axle insert which slides up the inside of the axle to help reduce stress at key areas. Reports say it works well. And then we come to bodywork where as I explained last month the CIK have managed to drop everyone into a tricky situation. What a caring, thoughtful governing body they are! The positive news is that as a result of pressure levied by myself and others in the UK, the MSA have put pressure on the CIK to help make the situation somewhat simpler. Though as of the day I write this at the back of October the situation is still somewhat floaty. But hope that new droopy front noses will be able to be fitted with a converter which stops them drooping. And some sort of compromise will be reached on the side bars to make them sensibly compatible. If you can buy a current stuff then do so – it will make a perfectly useable spare for less hassle!

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TKM Insight

stock-tkmTwo small changes have been made to the engine regs for TKM you might just have missed. Grahame Butterworth explains.

If you’ve read the 2015 regs and engine fiche, you’ll have spotted these changes. But for everyone else, here’s a quick insight. First to pistons on Junior engines. For many years we have had a situation where the Extreme 115cc engine uses a single ring piston while the Juniors remain on twin ring. Now that is changing. The decision has been taken
to simplify this situation for the benefit of drivers and scrutineers. TKM testing has shown no quantifiable difference in performance between one or two piston rings and no increase in piston and/or cylinder wear.
In reality these days you will find very few, if any, other kart racing 2-strokes using twin ring pistons. So with immediate effect it is permied to remove the boom piston ring in the Junior BT82 100cc engine if desired. Note 100cc Junior pistons from Tal-Ko and those fied in new engines will have two rings fied.

The removal of the lower ring is down to driver or engine builder Don’t expect to suddenly find a performance increase in removing the boom ring because as I’ve said we can find no measurable gain from removing it. And remember that with no boom ring the seal of the top ring is even more critical. That makes the short-term easier but there is also a longer term solution. At some point in the future when stocks of the current twin ring 100cc pistons are finished, we’ll switch to the supply and fiing to new Junior engines of simpler single ring pistons. These new single ring pistons are slightly cheaper to manufacture and so will save you some money. But they won’t be available for some time so carry on with the current twin ring piston until they are available and make your own choice on whether to have one or two rings in place. And whatever rings you have in place they must still be at least 50 per cent free to move in the ring groove.

Next to big end crank pins, a small component which takes on a massive job, and can result in catastrophic damage if it fails. They have been made stronger over the years to stand the extra strain, and now there is a new one aimed specifically at those engines past their best. It means for a few extra pounds you can keep a worn old engine in use without having to pay out lots on new parts. Interested? I’ll explain more next month.