Finest DRZ/KLX 125 Mods: Is It ACTUALLY Price Upgrading?

In search of one of the best DRZ125 mods on your Suzuki or Kawasaki 125 path bike however undecided the place to begin? Whether or not you desire a extra snug journey or are constructing a aggressive racing machine out of this “little women bike”, you’re in the suitable place!

On this article, I’m going to point out you what sure mods and upgrades truly do to your DRZ 125 or KLX 125 filth bike, why you need to or shouldn’t modify some elements, and learn how to construct the mix finest on your particular wants & finances.

Earlier than you begin modifying your filth bike…

“It’s straightforward to begin throwing elements at your filth bike or bike to improve the efficiency, after which whenever you go to journey it, you discover that it doesn’t really feel or journey the identical. That’s as a result of it’s straightforward to make the error of doing too many mods without delay or not correctly planning which of them work effectively collectively.

2020 Suzuki DRZ125L Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?

You see, simply upgrading the suspension or tires would possibly give it extra efficiency, but it surely actually will depend on the place you’re going to be driving and what your preferences are. Most inventory bikes already work very effectively, so in case you don’t need to blow out your financial savings account, selecting the best mods can prevent some huge cash whereas nonetheless providing you with a greater or extra snug KLR 650.”

What are your targets for this bike construct?

There are a couple of completely different instructions you’ll be able to go in relation to modifying your DRZ 125 or KLX 125. For instance, you might improve the suspension and energy efficiency in case you’re an grownup who desires a extra succesful path bike. 

You can even spend much more money and time constructing out the engine and changing the forks and shock to journey extra like a mini motocross bike. 

Or in order for you the finest low cost and free DRZ125 mods, there are some straightforward methods to make it quicker, safer, and extra snug for you or your little one to journey. 

Airbox/Consumption mod

One of many best mods is the air field snorkel mod. The inventory air field on the DRZ 125 and KLX are pretty restricted, which is nice as a result of it retains out filth and water higher, but it surely additionally chokes the engine. 

When the air field is opened up, there’s extra potential to suck extra air into the engine, which lets you make extra energy. By eradicating the snorkel/lid on high of the airbox, extra air can get in. 

2003 Kawsaki KLX125 Air Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?

It gained’t make an enormous distinction, but it surely’s free and also you would possibly get somewhat higher throttle response when tuned correctly, which I’ll cowl shortly. One other technique to enhance airflow is with some uni filter vents (see worth on Amazon). 

Air filter backfire display – take away it?

Many filth bikes include a metallic display within the airbox (after the filter) to forestall an engine backfire from exploding into the airbox and beginning a hearth. This may be eliminated at your personal threat.

The display restricts airflow, however you most likely gained’t really feel a lot distinction by eradicating it by itself.

Will you might want to re-jet after an air field mod?

It actually will depend on the way it’s tuned earlier than the air field mod. If it’s correctly tuned or jetted too lean, you then’ll most certainly want to regulate one or a number of jet circuits to get it to begin and run effectively.

Modifying the air field and consumption will enable extra air in, providing you with a leaner air-fuel combination, which makes it more durable to begin and bathroom in colder and dryer climates. Step one to adjusting the jetting is with the gasoline screw.

Jetting – extra advantages than you assume

The inventory DRZ 125 (and KLX) is pretty lean from the manufacturing unit, particularly in case you uncork and begin modifying the consumption, exhaust, and engine. If you happen to don’t regulate the carb jets, it should doubtless be more durable to begin and run worse, providing you with these annoying signs:

  • Gained’t begin
  • Gained’t idle
  • Bogging on acceleration
  • Backfiring
  • Plug fouling
  • and so forth.
2007 Suzuki DRZ125 Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?

Right here’s a fast chart evaluating the inventory vs advisable jetting specs for an uncorked DRZ/KLX 125:

Inventory DRZ/KLX 125 jetting (Mikuni VM20 carb):

  • Pilot: 17.5
  • Major: 102.5
  • Needle: Non-adjustable

Beneficial jetting for 1000 ft. @ 70F deg (uncorked):

  • Pilot: 20
  • Gas screw: 1.5 seems
  • Major: 105
  • Needle: TTR125 Needle (Adjustable)

Suspension improve – why you would possibly want it

The inventory suspension might be the weakest hyperlink on the KLX and DRZ 125 in case you’re an grownup or aggressive rider. It’s good in case you’re a newbie or informal path rider that weighs lower than 120 lbs, however greater than that and also you’ll begin bottoming out the forks and rear shock.

What occurs in case you backside out the suspension?

Bottoming the suspension is whenever you totally compress the forks and/or rear shock – you’ll really feel and normally a “clank” or “thud”. This isn’t good since you’re much more more likely to break elements, similar to cracking the body weld, and it may additionally throw you off the bike in case you’re not anticipating it to harshly bounce again.

Because of this it’s so essential to get the correct spring charges based mostly in your weight and driving fashion. It’s okay to backside out the suspension each every so often, however in case you’re bottoming a number of instances inside quarter-hour of driving, then your DRZ/KLX 125 suspension is means too smooth for you.

2003 Kawsaki KLX125 Front Forks Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?
The inventory forks depart so much to be desired in relation to efficiency

Fork upgrades – what are your decisions?

There are a number of methods to make your DRZ125 or KLX125 entrance suspension carry out significantly better, whether or not you’re only a informal path rider or an aggressive rider or racer. You are able to do some low cost mods that can make a noticeable distinction, or you’ll be able to spend much more money and time changing to forks from a unique filth bike.

These are one of the best DRZ/KLX 125 fork mods:

Heavy responsibility springs

If you already know you want stiffer forks, then simply order some heavy-duty fork springs (examine worth on Amazon). This alone will maintain the entrance find yourself larger and assist forestall bottoming and diving beneath heavy braking.

Professional Tip: If you happen to discover that utilizing 2 heavy-duty fork springs is just too harsh and uncomfortable, you too can strive 1 of every spring (1 stiff/1 inventory). This may break up the distinction in spring charges, making it stiffer than inventory however not as stiff as having 2 stiff springs – make sense??

Preload spacers

Did the aftermarket fork springs assist however you continue to need somewhat bit extra “hold-up”? In case your forks are too low within the stroke earlier than hitting bumps, you then both want stiffer springs or extra preload.

By including a PVC spacer to the forks above the springs, you enhance the preload, primarily making the preliminary motion of the forks stiffer. Begin with ½” increments in lengths, and it’s finest to make use of (thicker) Schedule 80 PVC pipe that’s simply barely smaller than the within diameter of the forks.

Fork Preload Spacer Block PVC Pipe Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?
Instance of a preload spacer that’s very lengthy

Low cost re-valve

Are the springs stiff sufficient however you need to decelerate the compression and rebound damping on the cheaper? Switching to a heavier-weight fork oil (Test worth on Amazon) is a reasonably low cost technique to decelerate (stiffen) the entrance forks in relation to the damping (how briskly the forks go up and down when hitting bumps & obstacles).

Ship to a tuner that is aware of conventional-style forks

Unline fashionable USD forks on MX and enduro bikes, the KLX and DRZ125 have quite simple standard fashion forks that make it somewhat more difficult to “re-valve” or tune them for higher efficiency. If you happen to plan on holding your little 125 path bike for some time or need essentially the most consolation for the least cash funding, I like to recommend sending your forks to Bruce Triplett in North Carolina or a suspension tuner that is aware of learn how to correctly arrange damper-rod fashion forks based mostly in your weight and driving fashion. 

Bruce is extra reasonably priced than you would possibly assume and does an ideal job – he made my inventory CRF230F forks work nice for the woods and mountains!

2004 Kawasaki KLX125L 3 Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?
Modified inventory forks can work pretty effectively

Fork swap/conversion – is it value your time & effort?

Need much more efficiency than the inventory forks, similar to extra suspension journey or higher bottoming resistance? Upgrading to forks or a front-end from an 80/85cc motocross bike is the way in which to go if in case you have somewhat greater finances and time to do the fork conversion – some forks require some mods/fabrication to suit and performance correctly.

RM80 forks

Requires RM 80 forks and triple clamps on the minimal. They’re RSU (standard) forks that provide extra journey and efficiency, in addition to rigidity on account of being bigger in diameter in comparison with the inventory forks.

They bolt onto the inventory DRZ/KLX 125 entrance finish, however they’re about 3.5 inches longer, throwing the geometry off.  You’ll be able to slide the forks up within the clamps barely (they’ll run into the bars), in any other case, you’ll be able to internally shorten the forks or mod/improve the rear finish to steadiness out the suspension.

KX85/KX100 forks

Requires KX forks and triple clamps on the minimal. Supposedly the inventory axle/nut match. This will even trigger the font finish to be excessive (chopper impact).

You’ll need to decrease the forks by elevating the within the clamps, internally, or increase the rear shock.

One other supply mentions these necessities:

  • An RM axle. The diameter is similar because the DRZ’s, it’s just a bit too quick
  • RM85 entrance brake disk. For no matter motive, they made a unique dimension
  • Longer caliper bolts – the mounting level is similar for the brake caliper, however the RM forks have a thicker mounting floor

Shock upgrades – matching the entrance forks

If you happen to’re upgrading the forks, then you’ll want to do the identical or much like the rear shock or else you’ll have a poor dealing with filth bike. For instance, if the forks are a lot stiffer however you allow the shock smooth, the rear finish will sit decrease and trigger the entrance finish to scrub out extra simply.

Spring fee

A stiffer shock spring (examine worth on Amazon) will steadiness out the suspension if in case you have stiffer springs within the forks. It’s a reasonably cheap improve that can make a giant distinction if the inventory shock is just too smooth for you.

Free journey top adjustment

Adjusting the preload could make the rear finish somewhat bit stiffer or softer, but it surely’s primarily to get the correct journey top. In case your DRZ125 rear finish is just too low, for instance, it should really feel softer and the entrance finish will slide out extra simply as a result of there’s an excessive amount of weight on the rear.

It’s free to regulate the shock sag/preload with a shock nut wrench (examine worth on Amazon) or a hammer and punch in case you’re cautious, however it may make a noticeable distinction in your security and confidence when your suspension is correctly balanced for higher dealing with.

To extend the shock preload:

  • Loosen the higher shock spring collar nut
  • Flip the decrease collar nut down (clockwise)
  • Tighten the higher locking collar nut when completed

Rear shock improve – what’s accessible?

There aren’t many choices for aftermarket rear shocks in relation to the DRZ125 & KLX125 – they’re not as well-liked because the TTR125 or CRF125F for upgrading.

Principally, you’ll be able to both spend quite a lot of time looking for a used Works Efficiency rear shock, or try to adapt a shock from an 85cc MX bike, such because the RM85, KX85, or CR85.

2020 Suzuki RM85 Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?
RM85 suspension can deal with extra aggressive driving

You’ll need to do your personal analysis for the precise particulars, however right here’s what I discovered that’s required on the minimal to make these shocks work:

  • RM85 shock: The higher mount is just too slim (might be widened), the higher chain curler wants relocation (hits shock physique until there’s room to put in it the alternative means), and this raises the rear finish about 2”
  • KX85/KX100 shock: Identical as RM shock
  • CR85 shock: No mods required to suit relying on which facet the shock reservoir is on, raises the rear finish about 2”

Are you able to decrease the seat top?

Possibly you want your 125 path bike, but it surely’s just a bit too tall on your liking as a result of it’s too straightforward to fall over whenever you come to a cease. Sadly, I haven’t discovered a great supply for a decreasing hyperlink equipment (Amazon), however you’ll be able to decrease it by no less than 1 inch without cost.

You simply have to lift the forks within the triple clamp and decrease the rear shock sag. So long as the entrance and rear suspension are at a balanced top, it ought to nonetheless deal with effectively – plus you’ll be able to increase it again up whenever you construct up your confidence utilizing protected strategies.

Gearing – low cost efficiency improve

Though it gained’t offer you extra energy, you’ll be able to have quicker acceleration or the next max velocity with a easy gearing change. That is most likely the best and most cost-effective technique to make your energy really feel completely different, but it surely’s not for everybody in case you just like the inventory gearing.

Higher acceleration for off-road

The small wheel mannequin has a 51T rear sprocket (examine worth on Amazon), however going as much as a 57T gives you an ultra-low first gear with faster acceleration.

Nevertheless, I wouldn’t advocate this mod until you really need extraordinarily shut gearing – first gear can be so low that it’s just about unusable until you’re at a crawling velocity.

Increased high velocity for cruising

The inventory entrance countershaft sprocket is a 14T on each fashions, so going as much as a 15T entrance sprocket (examine worth on Amazon) gives you a barely larger high velocity and unfold out the gearing so that you don’t need to shift as a lot.

This can be a good mod if in case you have upgraded the engine as a result of the additional torque can deal with wider/longer gearing.

Finest DRZ125 Exhaust improve

The inventory exhaust is nice in case you want a quiet filth bike so that you just don’t annoy neighbors, but when sound isn’t a difficulty, then you’ll be able to unlock some horsepower and throttle response by modifying the inventory exhaust or upgrading to an aftermarket head pipe & muffler.

These are one of the best DRZ and KLX 125 exhaust mods based mostly in your finances:

Free exhaust mod

The best technique to make extra noise and probably get somewhat extra throttle response is by eradicating the baffle/finish cap out of your inventory muffler. It’s the three bolts on the top, however it might trigger your KLX/DRZ to run worse.

Because it’s permitting extra exhaust to circulation, this could make it run leaner. If you happen to’re listening to backfiring on deceleration or it’s more durable to begin when the engine is chilly, you probably need to tune the gasoline screw.

2006 Kawasaki KLX125 Muffler End Cap Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?

Low cost exhaust mod

The subsequent finest improve is by eradicating the inventory finish cap, however changing it with a low cost billet tip (examine worth on Amazon). It gained’t sound as raspy, however you’ll nonetheless get improved circulation for higher throttle response whereas wanting significantly better than no cap in any respect.

It’s going to even be louder than inventory, so I don’t advocate these exhaust mods in case you dwell in an space the place noise is a priority and will get you or the driving place shut down from complaining neighbors.

Finest slip-on exhaust

If you happen to can afford an aftermarket exhaust improve, the following smartest thing is to put in an FMF powercore 4 slip-on (examine worth on Amazon). It’s a mid-pipe and muffler that replaces the inventory unit whereas nonetheless with the ability to use the inventory head pipe. 

It’s barely cheaper than a whole exhaust improve however you get the advantages of a top quality sounding exhaust that weighs much less and offers you somewhat higher throttle response.

Finest full exhaust improve

In order for you essentially the most energy, then putting in a full pipe and muffler combo, such because the Professional Circuit T4 system (examine worth on Motosport) is the only option – and it doesn’t value far more than the FMF slip-on for this bike!

It’s lighter, appears cooler, sounds higher, and gives you higher energy than the inventory exhaust system when tuned correctly. It additionally comes with a detachable spark arrestor that makes it authorized to journey on state trails.

2009 Suzuki DRZ125L Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?
Professional Circuit T4 Exhaust system (faucet picture to examine worth on Motosport)

Do it’s important to re-jet the carb after putting in an aftermarket exhaust?

For finest outcomes, you’ll most certainly need to tune the carb with an aftermarket pipe or muffler, though it may not require a lot. For instance, you would possibly simply must take a couple of minutes to tweak the gasoline screw.

In any other case, you’ll be able to check with the advisable jetting specs earlier on this article for a great place to begin in case your DRZ or KLX125 is near inventory.

Engine upgrades

After you have a suspension setup that may deal with your weight and the consumption and exhaust are maxed out, upgrading engine elements is one of the best ways to get much more energy out of your DRZ125 or KLX.

2005 Kawasaki KLX 125 2 Best DRZ/KLX 125 Mods: Is It ACTUALLY Worth Upgrading?

One improve might not assist a lot, and a number of mods might make your filth bike more durable to journey if you’re correctly combining mods to work collectively. 

These are one of the best engine efficiency mods:

Increased compression

These air-cooled engines have a reasonably low compression ratio to start with to allow them to deal with lower-grade gasoline, which suggests it’s straightforward so as to add compression with a unique piston. Including compression mainly makes your engine pump out extra energy as a result of it may compress and ignite a bigger combination of gasoline and fuel.

A Wiseco excessive compression piston equipment (examine worth on Amazon) is an efficient technique to give your 125cc filth bike somewhat extra “oomph!” Whether or not you’re simply eager to improve or your OEM piston and rings are worn and inflicting your engine to smoke, this can be a good and dependable mod when put in correctly.

Can you continue to run pump fuel with excessive compression?

Sure, so long as you’re operating contemporary 91 or 93-octane pump fuel (no ethanol is finest), you shouldn’t have any issues with detonation, which is extra frequent on high-compression engines. 

This piston equipment claims to have an 11:1 compression ratio, which is mostly the very best you’d need to go on an air-cooled engine earlier than needing to run no less than a combination of racing gasoline to lift the octane ranking.

Professional Tip: Since this Wiseco piston is “cast” vs the inventory “solid” materials, you might want to take somewhat bit longer to heat it up as a result of the cast aluminum requires barely longer to “broaden”. An additional 1-2 minutes needs to be sufficient until it’s beneath 40F levels outdoors.

Massive bore equipment

The subsequent step up is including displacement – making your filth bike engine a much bigger “CC”. You’ll be able to both select the cheaper piston equipment choice (view worth on Amazon), or the total Athena model large bore equipment (examine worth on Amazon).

The 58mm piston equipment solely provides you an additional 5cc, but it surely additionally provides compression for somewhat extra torque. It’s a great choice if:

  • You want a brand new piston & rings
  • You’re on a finances
  • You’ve entry or a machinist pal that may correctly bore out your inventory cylinder

The Athena large bore equipment punches your DRZ/KLX engine out to 152cc, which is near a 20% enhance is displacement dimension. It’s a bolt-on equipment that comes with the piston, cylinder, and the whole lot you might want to rebuild the highest finish – in case you can change the inventory piston, you’ll be able to set up this equipment.

Horsepower distinction with a DRZ125 large bore – what to anticipate

If the consumption and exhaust are nonetheless inventory, then upgrading to a giant bore equipment gained’t be an enormous enchancment, however you’ll discover extra low-end and midrange torque. To get a greater total horsepower enhance, you’ll need to get a greater flowing exhaust, open up the air field, and correctly tune the jetting in order that it’s not wealthy or lean.

190cc large bore equipment choice?!

Need to go all out for an final DRZ125 construct? affords a 190 large bore equipment (188cc) if in case you have a thicker pockets and need to destroy your 125 or 150cc path bike associates in a horsepower and acceleration battle.

It’s not low cost, however you get what you pay for. They produce other choices for a carb and exhaust improve that may get you as much as 20 horsepower – That’s about 3 instances greater than a inventory DRZ125!


The subsequent restriction is the inventory cam. It doesn’t open the consumption and exhaust valve sufficient to achieve its full potential if in case you have a much bigger engine, exhaust, and better-flowing consumption.

By upgrading to a correctly matched camshaft, you’ll be able to see a pleasant enhance in efficiency. Since they’re not a preferred aftermarket half for the Kawasaki and Suzuki 125 4-stroke engine, the one place I’ve discovered them is from

Head work

The final large choking level is the cylinder head. When the consumption and exhaust ports are left inventory, the larger consumption, engine, and exhaust nonetheless can’t circulation and make as a lot energy as they might.

Nevertheless, simply making the ports greater isn’t all the time finest and it may truly kill your energy curve. That’s why it’s essential to discover a respected store that is aware of these air-cooled engines and what they want based mostly on YOUR particular engine wants.

Placing all of the mods collectively

If you put the suitable mods collectively, you should have a quicker, safer, and better-performing filth bike, however in case you simply select random upgrades on your DRZ125 or KLX125, it could be more durable to journey and run worse.

Right here’s a easy checklist of one of the best DRZ/KLX 125 mods based mostly in your particular wants:

Finest DRZ/KLX 125 upgrades for path driving:

  • Air field mod
  • Jetting
  • Fork improve on your weight
  • Shock improve on your weight
  • Upgraded exhaust with spark arrestor

Finest DRZ/KLX 125 upgrades for racing:

  • Air field mod
  • Carb improve/Jetting
  • Taller gearing
  • Stiffer forks
  • Stiffer shock
  • Massive bore equipment
  • Racing camshaft
  • Head work
  • Excessive flowing exhaust
  • Lightened flywheel

The most effective mod to make you a greater rider

You are able to do all of those mods, however they gained’t make as a lot distinction as this final one can. Too many individuals try to learn to develop into higher riders on their very own, however this results in forming unhealthy habits that trigger you to make use of means an excessive amount of vitality and fall extra typically.
I need to present you learn how to kind constructive driving strategies so that you just keep protected and have extra enjoyable – click on right here to get this strategies information at this time for FREE.