Best CRF50 Mods For Adult Pit Bike
Looking for the most effective mods for your Honda CRF50 or XR50? There’s an unlimited supply of aftermarket pit bike parts, but this guide only covers the best ones that improve your 50cc bike’s performance.
Whether you’re looking for cheap mods or the best one for gaining horsepower, this list includes them all for the CRF50F:
- Rear Shock Spring
- Fork Springs
- Reinforce frame
- Tall Seat
- Wide Pegs
- Triple Clamps
- Exhaust System
- High Compression Piston
- Big Bore Kit
- Thin Copper Head Gasket
- E22 Cylinder Head
- Stroker Crank
Cheap or Free Mods
Free performance is hard to pass up, so we’ll look at the best free and cheap mods for your CRF50 first:
- Lightened Flywheel
- CRF70F Carb
- Remove and plug choke
- Heavy Duty Clutch Springs
- Uni Air Filter
- Exhaust Tip
- Cylinder Head Breather?
Lightened Flywheel Mod
Removing material from the flywheel is an effective and free mod if you have access to a large. It won’t add any horsepower to your CRF50, but it will improve throttle response and allow the engine to rev up quicker.
The stock flywheel is fairly heavy, so reducing the several ounces won’t have much of a negative affect.
CRF70F Carb Swap
Upgrading to a CRF70 carburetor is a simple and relatively cheap mod because you can find them used on eBay. The CRF 70 has a larger carb, which will pull more air through than the smaller CRF50 carb.
Caution: only doing this mod will more than likely lose bottom-end power because the 50cc engine has a specific carb size.
It’s best to do a combination of mods that work together to get the best results. More on this later.
Remove The Choke & Plug It
Removing the choke from a stock carb is another effective and virtually free power mod. The choke is a butterfly valve that opens and closes in the carb bore.
However, even when it’s closer, it still takes up some space, reducing the amount of possible air going through.
The more air you can get through the carb, the more potential power you can get.
Upgraded Air Filter
In order to get more power, you need more air and fuel. Fuel can’t be properly burned unless there is enough air or else it will run rich.
The stock CRF50 air filter is nothing special when it comes to performance. Upgrading to a higher flowing air filter will give you better throttle response and more horsepower potential.
Want faster acceleration? Swapping sprockets to change the gearing is and easy and cheap way to make it feel like your 50cc pit bike is faster.
Changing the gearing doesn’t actually change the torque or horsepower. It just shortens the final drive ratio, so it reaches the max RPM in each gear quicker.
The bigger and more powerful the engine, the taller gearing you can make use of because it can pull it. Just something to keep in mind as you modify your CRF50.
Heavy Duty Clutch Springs
A stock Honda 50 is built for a 50lb kid. If you weigh 125lb+, you’re going to tax the clutches.
Yes, it’s a semi-automatic transmission, meaning there is no manual clutch. But there is still a clutch, and the stock springs can only hold so much pressure.
The more power you add and the heavier the rider, the quicker the stock clutch will fail. Upgrading to some heavier duty clutch springs will help eliminate this problem.
A cheap way to open up your stock exhaust is with a simple aftermarket exhaust tip. The stock baffle is pretty restrictive, so a more open tip will promote more flow.
Rejetting may be needed to correct a lean condition and get the most power.
Cylinder Head Breather Kit
This mod is cheap, but only necessary if you have a big bore or stroker kit in your CRF50.
It simply exhausts the extra crankcase pressure that the bigger displacement engine puts out.
Best Performance Upgrades
There’s an endless list of possible mods you can do to your CRF50, but we’ll just go through the best ones that actually improve the performance. This includes suspension, engine, or frame mods.
Rear Shock Spring
The stock suspension on an XR or CRF 50 cannot handle the weight of an adult unless you’re just riding on flat ground. Even then a spring upgrade will improve your ride and not bottom out so easily.
Going with a heavy duty rear shock spring (Amazon) is an affordable way to stiffen the stock rear shock.
If you’re going to stiffen up the rear, you’ll need to stiffen the front to balance it out. Heavy duty forks springs (Amazon) are relatively cheap and really help the stock forks prevent bottoming. Constant bottoming of the forks will result in damage to the forks or frame, as well as causing a higher probability of crashing.
Speaking of frame damage, proper reinforcement is smart if you’re going to be jumping your CRF50 or riding it aggressively.
Adding a simple frame cradle is cheap insurance. The engine is the support for the frame, so if it flexes too much, the motor mounts will break.
The frame cradle supports the engine and the footpegs, so you can ride harder without bending or breaking parts.
Pit bikes are called pit bikes for a reason. They’re modified mini bikes, so they’re really too small for adults to ride comfortably.
Replacing the stock seat with a tall seat makes a big difference, giving your legs a little more room to work with while riding.
The stock footpegs are small and low performance because it’s a little kids dirt bike. Upgrading to wide footpegs gives you more stability and grip.
Now that you’ve raised the seat, the handlebars are awkwardly low. Tall mini bars are a cheap way to really open up the cockpit. They’re also stronger than stock, so a simple tip over won’t bend them as easily.
Looking for the best performance and durability? Upgrading to a better triple clamp gives you better strength and versatility in bar mounting options.
Or you can just get the complete handlebars and triple clamps mount kit. This Pro Taper kit is ready to go. Just know that consumers have had trouble with the throttle assembly from it, so you may not be able to use it if those parts are of poor quality.
Alright, now it’s time for the almighty exhaust mod. Replacing the stock CRF50F is one of the most common modifications because it’s easy, relatively cheap, and there’s big gains… at least in sound.
Okay, yeah there’s some power gains to be had as well with a good aftermarket exhaust.
A cheap knock-off system (Amazon) can be had for under 100 bucks if you want a little more power and more noise.
FMF, Pro Circuit, and Two Bros make quality pipes for the CRF50 if you want the best.
High Compression Piston
Want more power but can’t or don’t want to go bigger on engine displacement? Adding compression with a high compression piston is one of the best ways to boost torque and horsepower on your 50cc Honda pit bike.
Big Bore Kit
An 88cc big bore kit (Amazon) is one of the best bangs for your buck when it comes to adding horsepower to your CRF50.
For about the same price as an exhaust system, you get almost double the engine displacement. The BBR big bore kit (Amazon) comes with everything you need, from the cylinder and piston to the gasket kit.
If your 50 needs an engine rebuild, or you just want quick and affordable power, an 88cc will get you there.
Getting The Most Out of Your Big Bore
An engine must work in unison with the intake and exhaust to produce the most effective power. If you have a big bore with a small stock carburetor and exhaust, it’s going to be choked up and limit your potential performance gains.
Upgrading to a bigger carb with proper jetting and an aftermarket exhaust will really let the bigger engine breathe and run at it’s best.
Thin Copper Head Gasket
Are you part of the 1% that wants every power mod possible? While you’re rebuilding the top-end, use a thin copper head gasket to bump up the compression a little more. More compression equals more torque to make your CRF50F accelerate faster.
The camshaft on a 4 stroke is one of the most important pieces to building a strong engine. If you want maximum torque with a smooth powerband, going with a max lift racing camshaft will destroy your low-end power.
Keeping the stock CRF50 cam in a highly modified engine will greatly limit its potential and it will fall flat at higher RPMs.
E22 Cylinder Head
The cylinder is the other big link to piecing together the ultimate 4 stroke engine. Obviously the stock head is severely limiting how much air can flow through it without major porting work.
To save time, you can simply bolt on an aftermarket cylinder head that’s already designed to work with a modified CRF 50.
Going all out on your pit bike build? A stroker crankshaft (Amazon) is the last big piece to modifying your stock CRF or XR 50 engine.
It requires more work to get to the bottom end, but it’s just what you have to do for maximum engine size.
Complete Race Kit
TB Parts offers a complete performance package (Amazon) that includes the entire crank, top-end, upgraded carburetor and all the gaskets needed to put the engine back together. For how much you get, it’s not that expensive.
It’s not some cheap unknown name kit, so the parts are better quality. It costs less than an aftermarket exhaust for a new motocross bike, but the percentage of gains is huge.