The best way to make a 2 stroke go faster is to have a big bore kit fitted. A big bore kit is when the entire top end of the dirt bike engine is replaced and the engine is increased in size by about 50cc. This means that instead of having say a 250cc, you will have more like a 300cc. This modification will boost the bottom to mid-range horsepower by about 15% and will give you more power than all other mods combined. If you have never done a top end rebuild before I recommend taking it to a mechanic to get it done for you. A big bore kit will cost about $500 to buy plus the cost for a mechanic to have it installed. More details and other mods explained below.
#1 Make sure your bike is mechanically A1 first. Tires, jetting, air filter, etc
#2 A big bore kit will give you more horsepower than all other mods combined.
#3 Remove any restrictions in your pipe and air filter (uncorking).
#4 Upgrade the jetting.
#5 Buy a performance pipe.
#6 Get the engine ported.
#7 Buy a Lectron carburetor.
#8 2 things you should never do!
#1 Make Sure your Bike is Mechanically A1 First.
Difficulty: MEDIUM Cost: ESSENTIAL
You can put on all the mods and upgrades in the world but if your dirt bike is not healthy, your 2 stroke will not go any faster.
Tires. First make sure that your tires have plenty of tread. Worn out tires mean that the you are losing all your horse power in the back wheel.
Carburetor. Is your carb healthy? When was the last time you cleaned it out. If your carb cannot breathe properly or cannot get the gas into the engine properly, you will be losing big horse-power.
Jetting. How is the jetting in the carb? Is it running too rich or too lean? Are they to spec of the dirt bike? Make sure you are running the right jetting for the bike because if they are incorrect then you will be losing horse-power.
Air filter. Check the air filter and clean it out regularly. If the air filter is dirty or worn, it may be choking your engine of much needed oxygen. A dirty filter is a definite reduction of power.
Spark plug. A worn spark plug will slow down your acceleration and power. How? A spark plug is made up of important metals that create maximum spark which in turn causes maximum combustion in the engine. If there isn’t maximum spark then you will feel a loss of power on the wrist.
Suspension. Suspension is a big problem to horse-power if your suspension is worn out. How? Well if the suspension is too squishy then some of the power of your bike will be transferred into the softness of the suspension leaving you with a whole lot less power.
I would recommend doing these things first before attempting any other modification.
#2 Get a Big Bore Kit.
Difficulty: DIFFICULT Cost: EXPENSIVE
A big bore kit will do more for horse-power for your 2 stroke then any other modification you can find on the internet.
A big bore kit will completely replace the engines top end and the piston with larger ones which in turn increases your engine capacity, making your 2 stroke go faster.
If you have a 250cc then a big bore kit will upgrade your engine to 300cc which provides an obvious boost in horse-power by about 10-15%.
A big bore kit should come in at about $1000 including install costs by a mechanic which is a whole lot cheaper than buying a new bike.
If you want to have a go at doing it yourself, study this video very carefully.
To find a big bore kit for your dirt bike, do a google search for your ‘bike make and model big bore kit’.
When you find a mechanic that does your bike make and model, give them a call and have a chat to them so you know exactly what you are getting into, what you can expect from it and what it is going to cost you.
#3 Remove Restrictions (uncorking).
Difficulty: EASY Cost: FREE
If you choose the uncorking option, you will need to change the jetting as well because your bike will run leaner than normal with all the extra air that is rushing through it. I have done a piece about changing the jetting in #4.
There are 3 places where your bike can be restricted – in the pipe, muffler and in the air box.
Dirt bike manufacturers like to restrict dirt bikes down in power to keep them within reasonable rev limits for general safety and optimal engine performance.
Also, they do it to stay within the guidelines of noise and pollution restrictions (especially if the bike is road compliant).
Removing them will make your dirt bike breathe easier and can make your 2 stroke go faster.
In the dirt bike world, this is called ‘uncorking’.
Pipe. First take off your pipe and shine a torch down the part of the pipe that connects to the engine.
If there is a small piece of metal that is closing off some of the pipe, remove it.
Air box. With some models of dirt bikes, the air box may have an air intake snorkel or a setup that is designed to restrict the amount of air that can be sucked into the air box by half.
If your bike has any if this on the air box, cut it off.
Also, some guys even drill holes into the air box to give it more oxygen to breathe. This will work as well (but obviously you will damage the air box).
#4 Upgrade your Jetting.
Difficulty: EASY Cost: CHEAP
The most effective and inexpensive way of increasing horsepower is to make sure that the fuel is mixing properly with oxygen and is supplying it to the engine as effectively as possible. This is done with jetting.
The jets are the little valves that sit in the carb and control how much gas is sprayed into the carb and engine.
Too little gas (lean) and that engine won’t have enough power, too rich and it will burn too much fuel and will be sluggish.
If you uncork your bike you will need to upgrade your jetting as the bike will run too lean from all the extra oxygen that is being pumped through the bike.
The best way to get this job done is to call your bike store and tell them your bikes make and model, modifications and ask for their performance jetting.
If they are a quality bike shop then they will be able to advise you on jetting properly.
If you want to get your fuel/air mixture perfect every time without having to worry about it, get yourself a Lectron Carburetor!
#5 Upgrade to the Lectron Carburetor.
Difficulty: EASY Cost: EXPENSIVE
The Lectron carburetor is made in Texas and is the latest technology in carburetors on the market.
Think of it like a smart carburetor that auto regulates the fuel/air mix so its perfect every time without having to do any ongoing adjustments.
I don’t completely understand how it works because they get into some pretty heavy science but all I know is that I put it on my bike and the power was instantly more responsive and it felt like it had more power overall.
The great thing about the Lectron carb is that you just plug and play. Simply remove the old one and bolt it on and you are good to go.
It will work at optimal performance without having to adjust it. There are no jets in this carb so no more trying to optimize your jetting. Very cool!
I recommend the Lectron ‘high velocity’ carburetor. It offers more power in the low and medium end.
Don’t believe me? Check out this video from Moto racer Jeff Walker who tested the Lectron against the standard carb in his Honda CR125.
With the Lectron he was able to shave 2 seconds off his lap time!
The Lectron carburetor will set you about $500 and it’s worth every cent.
#6 Buy a Performance Pipe.
Difficulty: EASY Cost: AFFORDABLE
There’s quite a bit of debate on whether a performance pipe can offer more horses than the stock standard pipe.
Some say that it does while others say that they smooth out the power across the rev range.
Well there is a reason why the most successful motocross and enduro racers in the world use aftermarket pipes.. because they work.
Depending on your bike, they may not increase overall horsepower but they will definitely give you more power where you need it which is the lower and mid-range rev range.
For around $200 you can easily install an aftermarket performance pipe and you will instantly feel a difference in power and speed.
Personally, I always go with FMF. They’ve been around for longer than I’ve been alive (40 yrs) and they know everything about performance pipes.
Check out the FMF Gnarly Torque. It’s the latest in the FMF line of performance pipes and the difference in power is impressive.
#7 Get your Engine Ported.
Difficulty: DIFFICULT Cost: AFFORDABLE
Porting is the process of polishing the inside of the cylinder of an engine around the air, fuel and exhaust ports.
Why do this? By making the gases flow in and out of the engine more efficiently you will eliminate ‘turbulence’ and makes the air flow as efficiently as possible through the engine.
Less gas resistance equals more speed, equals higher volume = more horsepower.
I don’t recommend you do this yourself as you need special grinding and polishing tools and you need to know what you are doing.
But for a few hundred dollars you can get a pro to do it for you.
I recommend Eric Gorr Racing in Wisconsin. Eric has been doing this since the 70’s and he’s one of the most knowledgeable guys for porting and rebuilding 2 strokes in the USA.
Give him a call on (630) 825-5645 and he’ll give you a quote over the phone. You can also send in your parts via the post to him so you don’t have to travel.
Here is a good video that explains what porting is, why it’s done and how to do it.
#8 What Not to Do.
I see these mistakes done all too often so I thought I would mention them in the off chance that you were tempted to do them.
a. Stop Using Racing Fuel.
Racing fuel is designed for dirt bikes that have been especially built to handle ethanol in their engines.
A stock standard dirt bike will LOSE POWER by using racing fuel as it just doesn’t know how to burn the high ethanol content efficiently.
b. Don’t Take the Baffle off your Muffler.
The baffle is the end cap of your muffler. Some guys think that if you take it off, the bike can breathe easier and you’ll get more power.
Wrong!! All that will do is make your bike louder. And louder doesn’t equal more power (although I bet you want it to 😀 ).
Let me know what you have done to make your dirt bike go faster. Have you used any of the above ideas? Let me know in the comments below. Also, if you liked this article please give it a share on social media.
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Taking off the silencer does make a bike go faster.
My first bike a Malaguti Grizzly 12 was slow and when I took the silencer off it was much faster down the straight and I timed it going down a straight and with the silencer taken off it was a much quicker time.