Mini Bike Modification Guide

It is common these days to see mini bikes being sold in stores already with performance parts fitted, such as K&N style air filters and performance exhausts, however there is always still more work to be done to these bikes.

They are incredible easy to work on and with such a basic engine the only knowledge needed to work on them is knowing how to use a spanner or a screwdriver.

Here is a list of modifications recommended in order to increase the overall power of the bike, as well as improving the handling and feel of the bike.

It would be an idea to start modifying the mini bike with the larger mods, as with these more performance is gained for the money spent. The biggest modification which can be done to a Mini bike is to get it bored out to a larger engine displacement. Most of these bikes will come with a 47cc (which is actually only 39cc). These engines can be bored out with a racing kit to 49cc. This will improve the power of the engine due to the larger displacement, improving acceleration and top end.

If the mini bike is already 49cc there are kits for sale which take the engine up to 58cc again having the same effects as before.

The next modification it would be wise to make to the mini bike is with a performance exhaust, these come in many makes and models and each style will have a different output to the next, so it is best to look around before jumping in and buying one straight away.

These exhausts work as they have an expansion chamber, which improves performance on any 2-stroke engine. These exhausts are not usually over expensive; the cheaper systems can be bought for under £50, and go up to over £200 for the more expensive systems. These are great bolt on performance parts, and can improve the acceleration of the bike with higher low and mid range revs, whilst increasing top end by up to 10 mph.

These exhausts will really benefit the bike if it has been bored out as well and the difference in performance will be evidently noticeable.

The next modification which could be made to the carburettor, and increasing air flow through the bike. Firstly, add a free flow air filter,(K&N style ones). This will mean the bike can take in more air, and the rule of thumb for any engine is - increased air intake + increased fuel flow = increased BHP.

Therefore this part will help with the performance of the bike, however if an air filter is fitted then the carb will need to be up jetted in order to cope with the extra air, performance is likely to decrease if these changes aren't made. Buying new jets for the mini bike increases performance as these jets will allow more fuel to be sent through the carburettor. Tuning will need to be done with this to get the air:fuel ratio correct.

It is recommended that if modifying the air and fuel intake of the engine that a carb upgrade is purchased. The standard carburettors in these bikes do not have as many adjustment screws as the performance carbs and therefore cannot be tuned as highly, and the performance benefits will not be as evident.

With these changes the bike should have better throttle response with better acceleration and also higher top end speed. This works very well with the performance exhaust and the extra performance with the bike should be easily recognisable.

Once the Mini bike has been up jetted and a free flow filter and new carb have been fitted then it is time to make some smaller adjustments to fine-tune the bike.

The next adjustment which could be made to the bike would be to add a rocket key, this allows the bikes timing to be improved for pulling away and accelerating, meaning that the throttle response and acceleration will be improved.

It is also likely that the gearing of the bike will need to be changed depending on where it is used. This is mainly done through different sized sprockets, and this will be changed depending on how the rider wants the bike to perform

If a larger sprocket is put on the front or rear of the bike then the top end will be improved whilst making accelerating slightly slower, however if the Mini bike is fitted with smaller sprockets then the acceleration will be improved whilst losing some top end. These sprockets can be changed depending on what track is being raced on.

Due to the modifications made to the bike to improve performance, some other changes will need to be made to the bike so it can cope with the extra power and maintain that good performance. Items such as an NGK spark plug or similar could be used. The standard plugs in Mini bikes are not very reliable and will not be able to cope with the power the bike is producing.

Also doing this will improve the starting of the bike as well as keeping the bike performing at its best all the time. Whilst changing this is it also a good idea to change the lead and coil going to the spark plug for maximum benefits.

Another aspect of the Mini bikes which could be tuned is the clutch system. The clutches on the bikes are automatic centrifugal clutches, which will wear very quickly if modifications are made to the bike. It is advisable to upgrade the clutch to a heavy duty clutch with heavy duty springs, these will last a lot longer and also can improve acceleration and throttle response of the bike.

With all this power now added to the bike it is advisable that you make changes to the brake systems on these bikes. Most of them come with half descent disk brakes anyway but upgrading the brakes may be a good idea, imagine racing around a track doing over 50 mph, and then coming to brake and the brakes just ain't man enough to handle the speed, this is why this change is recommended.

Once all this is done the bike will have been modified a great deal without going too mechanically into it and the extra performance of the bike will leave other bikes standing.

Just remember to always ride on Private land with the owner's permission and wear protective clothing.

The Best Bang For Your Buck Pocket Bike Modification

I always see alot of questions similar in nature to "Will this setup work with my bike?", "What parts should I buy?", "How much will this increase my power?" from newbies entering the sport, so I have decided to make a list of what pocket bike performance parts are best for your bike.

This list is for people on a low budget and also applies to those that have a bit of money to spend aswell. It will be set out in the format "Budget Mods", "Average Mods" and "Serious Tuner". Be advised that all CAG engines are different and performance increases vary on each bike. This guide should help you spend your money more wisely on the right modifications to get your bike going at it's full potential with the money you have to spend.

The pocket bike modifications listed are all available in Australia, but may need some looking around for. The prices listed next to each part is the general recommended retail price, please do not use this as a buying guide as prices will vary from different suppliers. Make sure to shop around for better prices, and also check with the supplier that these parts will fit your style of pocket bike.

Budget Mods:

Timing Key - Increases your engines timing by 10 degrees, cheap and VERY effective part, But please note this increases performance on some engines, but can also decrease performance in others, it depends what your timing is set at in the factory. (RRP $20)

Fibreglass Reeds - Replace your stock metal reed with a high performance Fibreglass one. Fibreglass reeds allow more and faster fuel into the carb, this resulting in a faster burning of fuel, which increases low, mid and top end power. (RRP $20-$30)

Performance Air Filter and V Stack - If your bike came with a black air cleaner instead of an air filter, its loosing potential power, by adding a high performance air filter and vstack your allowing more and faster air into your engine, which will increase performance and engine life. (RRP $30-$40)

Hi Flow Fuel Filter - This is not a performance mod but it is one of the most important things that should be considered when buying modifications, If your fuel line does not have a fuel filter, there is a very good chance that dirt or foreign objects have got inside your fuel and are now blocking your carb. By installing this cheap modification it protects your engine from harm by dirt, plastic, etc. It is a must for every bike . (RRP $7-$15)

HP Clutch Springs - All CAGS come with 3 shoe clutches, the major let down with these clucthes are the springs. A good set of HP clutch springs will make your acceleration alot better over stock and coming out of coners etc, you will have alot more power. A good cheap investment. (RRP $15-$25)

These mods are a very good starting point to modifying, these parts can be fitted if you have general engine knoweldge or instructions. The flywheel, clutch and carb must all be removed to install these mods, if in doubt you can take your bike to a pocket bike repair shop and they would gladly install them for a cheap fee.

Average Mods:

Fatboy Exhaust and Tank - This exhaust system is an awesome upgrade over the stock exhaust, many winning pocket bike racers around the world use this exhaust and swear by it. It's a very cheap upgrade and will really open up your engine, the Fatboy Exhaust is that big, it comes with a smaller fuel tank so the pipe can fit. (RRP $90-$160)

High Performance Carb - The stock CAG carb is only 12.88mm by upgrading to a larger carb etc. 14/14 or WT-603 which are the most popular choices in carbs when it comes to racing you increase your engines performance all round by allowing more fuel and air to get burnt and this will increase your low, mid and top end power. (RRP $90-$160)

Heavy Duty 2 Shoe Clutch - A 2 shoe clutch is better for light people, once it gets going its awesome alot better than a 3 shoe clutch with springs, the only down side to this modification is you must adjust the springs perfect for when the clutch engages. (RRP $40-$70)

High Performance Piston Rings - HP Piston Rings Offer more compression and are a good cheap investment, will give a small increase in power. (RRP $10-$20)

Lightened Piston - A lightened piston is alot better than the stock piston and is alot better quality, will give a small increase in power. (RRP $30-$50)

Ported Cylinder - Getting a cylinder ported to your engine is one of the most important mods that can be done, a cylinder with boost ports, larger exhaust ports and the correct squish set, will give an insane power increase, Very good for the money. (RRP $80-$90)

These mods are for the more experienced racer that can handle alot more power over stock, these parts will be best installed by a shop rather than risk doing it your self. You will be amazed at the power increase.

Serious Tuner:

2 Peice High Compression Headkit - A headkit consists of a cylinder, piston, extra cooling plate, a high quality spark plug and some even with a changeable compression dome, This is where your engine gets insane power, by increasing it to a 49cc not a 40cc like most CAG's. A head kit tuned to the rest of the engine correctly is the best value for money product. (RRP $100-$400)

Full Circle Stroker Crank - A full circle stroker is best suited to an engine wit a headkit. Installing a full circle stroker crank (FCSC) will make your bike a 52cc but to get this going perfect the crank must be balanced to your piston. This is done by experienced pocket bike shops, once you install the FCSC you will never want to ride a bike with a half circle crank again. (RRP $110-$130)

4 Petal Reed Cage - Allows alot more and faster fuel into your engine with 2 dual reed sections allowing for 4 reeds, this gives you improved fuel flow and power throughout low, mid and top end. You will not be dissapointed: (RRP $120-$200)

Zocchi CAG Race Pipe - Hand made italian race exhaust, cannot go wrong here will run absolutley awesome with a headkit and a good carb. Awesome power increase from low, mid and top end. (RRP $160-$200)

The real art to serious performance upgardes is getting your engine made to run perfect with the modifications. This is achieved with the correct porting and tuning. If the above modifications are ran with all of the average mods and a timing key, you will have an insaneley powerful machine. They will easily add 20 km/h to your top end with stock gearing. Also be advised while adding these mods a final gear change will be needed to get the most out of the modifications. If your engine is tuned and ported correctly you will be keeping up easily with stock watercooled pocket bikes, if not beating them. With all of these mods, they are not made just to be fitted onto your bike. The best thing you could do is to take it to your local pocket bike repair or performance shop and get them to fit everything correctly and tune the engine to the modifications, then it's just a matter of holding on :)