Servicing of the kart 

Much as one might want to disbelieve this, but there are a few competitors that arrive at the track for a day’s racing and essentially jump into the kart without doing much in the way of cleaning, checking or servicing of the kart or motor.  This certainly isn’t the correct attitude to adopt if you value your safety or if you are hoping to finish in one of the more serious point scoring positions.  Without the proper care and attention, the kart quickly becomes an ‘also ran’ with poor handling ability, below par performance, and could also pose a safety risk both to yourself and other competitors. 

The chapter is intended to provide some clarity on what to service on a kart and also how often to do these various checks.  Some of the items have been discussed in a little detail, whilst others are straightforward and require no further elaboration.

Check the regulations

Every year a number of competitors will get caught out by what seem like a petty rule change, and the worst case scenario is that it happens at the first round of a championship where you lose out on scores due to a technical infringement.  So, keep yourself up to date and read through the latest versions of your class regulations, any club or championship SR’s, and the karting regulations (aka the SSR’s).  Also, don’t forget to regularly check the relevant websites for new karting Circulars that may affect you.  You really don’t want it be you who is excluded for having your tyres rotating in the wrong direction or something equally silly.

Cleaning of the kart

One thing is for sure – a clean, well maintained kart with the correct setup never went any slower because of the effort that was put into it.  It goes without saying that it will be easier to spot any potential problems on the chassis and other components if it is clean.  Apart from that, you won’t get your hands or overalls dirty every time you need to make any other adjustments, get into the kart or lift/lower it from the stand.  It’s also dead easy to do – an air powered washer filled with a cleaning liquid, or even a petrol soaked rag works wonders and won’t damage the powder coating on the chassis.  If you are using a harsh fluid like petrol, ensure that you keep it well away from the tyres as these two don’t much like one another and the rubber compound will also be adversely affected.  Same thing applies to any rubber hoses on the cooling system. 

Tie rods and tie rod ends

Most tie rods are made of Aluminium which is a lightweight metal, but has the drawback of being fairly soft.  For that reason, the slightest front end impact with the kerb or another kart can result in one or both tie rods being bent.  Sometimes this can be ever so slight, but in most cases it is pretty severe and requires the rod to be replaced.

At either end of the tie rod, there is a Rose joint also known as a tie rod end or a ball joint.  Unfortunately, the quality of these components can vary a lot depending on the manufacturer.  By placing the kart on a stand with the steering facing dead ahead, it is very easy to check for wear.  Firmly grip the tyres using one hand for each wheel and try to move the wheels outwards and inwards whilst feeling for any slack in the system as well as observing the joints themselves carefully.  Any excessive wear (slop in the joint) means you should at the very least replace the affected joint, if not all of them simultaneously.

Front end settings

The caster, camber and toe settings on the kart account for a large percentage of how the kart handles.  So, even if you haven’t been involved in an accident, it is a good idea to check these settings on a regular basis with the proper tools such as a Sniper laser kit.  This is a relatively simple operation and takes no more than a few minutes, and you normally only need to check the camber and toe.

Hub studs

The studs that hold the wheel rim in place are an often overlooked item.  Remember that you are constantly removing the wheels to change tyres, and believe it or not, some folks forget to torque up the nyloc nuts properly afterwards.  Any looseness between the nut and the rim will result in movement between the two when on the track, and the threads on the stud will become damaged.  In extreme cases you can end up losing a wheel, having to replace all the studs, and fixing the now elongated stud holes in the rim.  You may even have to replace the rim itself if it cannot be repaired.  Any such repairs are also best left to an expert who know how to tackle such a job as it would involve both welding and machining of the rim.  The best option is to prevent the damage in the first place by doing periodic checks on the stud condition and remembering to torque up the wheels every time they are removed.

Accelerator cable

Also known as a Bowden cable, this is the cable that joins the accelerator pedal to the slide on the carburettor, and they are prone to some nasty failures.  Some of the more common ones are slippage at the pedal connection clamp (results in you not getting full throttle), fraying where the cable enters or exits the outer sheath (cable can break or become stuck), or becoming dislodged from the slide at the carburettor end.  The pedal stop should be adjusted so there is still a small amount of movement in the cable without it being as tight as a guitar string so it breaks.  Any of these situations can lead to a disastrous result for the race, so check these areas on a regular basis.

Chassis

A chassis can become prone to cracks because it is constantly flexing, but even more so if it is involved in an accident with another kart or hard object.  Some of the common locations for cracks to manifest themselves are at the welds of the seat attachment tubes to the larger chassis ones, at the bottom of the steering column, and just behind or under the front steering yokes.  Obviously these become easier to spot if the kart is clean.  They can vary from minor cracks that can be repaired by TIG welding, but in extreme cases can result in the chassis having to be scrapped.  If in doubt, consult an expert on chassis repairs. 

Nyloc nuts

These nuts provide a very effective means of ‘locking’ a bolted connection together to prevent it coming apart with vibration, and they are used extensively on a kart.  The nylon insert in the nut does wear over time, particularly if it is constantly being undone and re-tightened e.g. those on the front wheel hubs.  If you can turn the nut by hand so that the bolt thread is well entered into the nylon, then you should regard the nut as useless and it needs to be replaced.  Purely as an interim solution, the nylon end of the nut can be given a sharp blow with a hammer and this should be enough to compress the nylon sufficiently so that it again becomes tight.

Sprockets and chain

A worn sprocket is so often overlooked, and as soon as the teeth start to look sharp or hooked, you are losing power.  Lubrication is critical, and a good spray with high quality chain lube as soon as the kart comes off the track i.e. when the chain is slightly warm and the lube will penetrate better, is the minimum maintenance that should be considered.  The chain picks up a fair amount of dirt and debris, aggravated by the fact it is open and has a lubricant that invites the dirt to stick to it.  Cleaning of the chain and sprockets is thus essential to an efficient transfer of power, and that happens when all items are new or as good as new, and well lubricated.  Once a chain is fitted ensure that it is adjusted correctly with the proper amount of slack, and a total of 10mm movement (up plus down) from the nominal position is considered good.  Also ensure that the rear sprocket, chain and front sprocket all line up properly, otherwise you are promoting excessive wear and also wasting power to overcome the excess friction.

Rear axle

Occasionally remove the wheels and hubs and give the axle a spin.  If you can visibly see any run-out (movement) at the ends, then the axle is bent too much and it should be replaced.  You can also check if the axle is bent by using a dial test indicator (DTI) against the axle whilst you slowly rotate it.  Ideally you should ensure that the axle bearings are perfectly aligned and the chassis isn’t twisted before doing these checks.

Wheel bearings

Although it’s better than nothing, merely spinning the wheels and listening for any funny noises isn’t really enough and it is far better is to deal with each bearing individually.  Remove the bearing, rotate it in your fingers and feel for any grittiness. If it rotates in a smooth and silky way it’s usually fine, but anything else and you should scrap it.

Carburettor

There are small orifices inside the carburettor with quite a few of them being smaller than 1mm in diameter, and hence any partial blockage due to dirt, grass particles and the like can cause havoc with your performance.  For that reason one should clean the carburettor innards with clean fuel and pressurised air at least once on a race day.  When reassembling the carburettor, ensure that all the jets are firmly tightened back into position as failure to do so could lead to a technical disqualification.

Spark plug

This is one of the most important items on the kart and if in bad condition or not set properly, can very quickly affect your lap times.  Some classes require you to choose a plug from a specified range and they also specify a maximum allowable gap.  Ensure that the plug tip is clean of any build-up and soot, running a good colour, has the gasket in place, is gapped correctly, and is tightened down properly.  Don’t laugh about the last item – it happens and will lead to a major fall off in power.  Also ensure that the ceramic outside of the plug and the inner of the rubber boot are clean, because dirt in those areas can lead to a misfire.

Power valve

If you have a power valve on the motor (certain Rotax and Rok classes) it needs to be kept clean and adjusted correctly.  Use something like Scotch-Brite with carb or brake cleaner to remove sooty deposits on the blade.  Check it is fitted centrally and that it easily slides in and out.  Also check for damage to the rubber bellows within the valve.

Clutch

Periodically remove the clutch drum and the clutch from the motor.  Inspect the drum and clutch for cracks, the friction surface on the clutch, check all dimensions are within spec., and that there is not excessive grease on the inside of the drum.  Regularly clean and apply new grease sparingly to the needle bearings within the drum and don’t forget to refit the O-ring.