Painful sputtering noises are coming from your bike. Those sounds have correlated to a noticeable performance drop on the previous rides.
If you find yourself in this situation, the likely culprit is the carburetor. Spitting and sputtering are evidence that it’s time to do a re-jet.
Although the work can be a little complex for DIYers out there, it is a necessary task to keep everything performing as expected.
The Honda CR125 and CR250 are notoriously finicky with their carbs when there isn’t a PWK Air Striker isn’t installed.
Everything You Need to Know About the PWK Air Striker Swap
The PWK Air Striker swap is one of the best ways to save time and frustration when jetting problems cause the carburetor to keep fouling the plugs repetitively. The Mikuni carbs are notoriously terrible with the CR two-strokes from the 2000s, causing issues even with altitude or temperature changes. This change fixes it.
If you’re tired of having your plugs fouled constantly, the PWK air striker swap is a fantastic way to save some time and increase performance consistency.
When you have an older CR125 or CR250, swapping the TMX carb for this one solves a lot of problems.
You won’t need to make as many adjustments, and the performance is a 180-degree turn from what it is when you’re using the stock options.
What makes the PWK Air Striker a better overall carburetor? Although it comes with the same bore as the brand’s previous models, the evolution it brings to the industry is significantly better.
You receive two fins on the inlet side, quad vents, and some more minor differences.
The overall goal is to prevent bogging problems when hitting jumps and whoops, and the PWK does that with excellent consistency.
You’ll receive a crisp throttle response, whether you’re redlining it or in a simple idle, ensuring that you’re jetting correctly.
It runs so clean – you’ll think you’ve got an entirely different bike once you’ve got everything installed.
Remember to Install the Correct PWK Air Striker
Most people only convert their CR125s or CR250 to the PWK Air Striker, but more are looking at it as an option for the CR500.
Several different carb designs bear the Air Striker name. These PWKs also come with the same outlet and inlet diameters. Although the length is variable, they’ll all fit over the same intake boots.
That’s why you’ll want to pay attention to these three crucial differences when looking to swap your current carb for the PWK.
- The older style PWK Air Striker has a longer body and is distinguishable with the black screw top. You won’t find TPS (throttle, position, and sensor) are electronics on this design, with the length measured at 91 mm.
- PWK has an updated version that you can identify by the two Allen screws located on the top of the unit. It comes with TPS, although the body length is shorter – at 75 mm.
- A third option matches the newer style from PWK, but it doesn’t include TPS. Everything else is the same.
Some people add a fourth option to the PWK comparison, but that’s because they’re confusing the Keihin PWK with the Air Striker. The Keihin doesn’t come with the fins on the inlet side, which is how you can tell them apart.
What PWK Option Do I Need for My Bike?
If you’re ready to do the PWK Air Striker swap to start saving some time, it’s important to choose the correct option for your bike.
The easiest way to accomplish this result is to measure the placement. If the length is 91 mm, you know that the older version is needed.
When the measurement is 75 mm, you can choose the model with TPS or install one without it.
If you’re unsure of your measurements (or don’t have the tools to take one), you’ll need to know the year of your Honda CR125 or CR250.
The model years of 2000-2003 use the long-body style without TPS and need the longer Air Striker with a screw cap. It’ll have a black top when you look at it head-on.
When you have CR250, the 2001, 2002, and 2003 models use the same carburetor as the older CR125. If you have a 2000 CR250, you’ve already got the Air Striker installed – unless someone modified it on you.
Newer Honda CR250s (2004 and newer) use the two-stroke design and need the short-body option from PWK.
If your bike doesn’t already have a TPS carburetor, you’ll need the older long-body version Air Striker that comes with a screw cap. When it does have TPS, you want the short-body alternative.
Some people have put the long-body PWKs on CR250s from 2004 to 2007 with success, but you won’t be using TPS with that option.
As long as the length is close to the stock carb, the fit should work well enough for you to achieve the results you want to see.
Popular Bikes That Already Come with a PWK Air Striker
Although you can grab an Air Striker new, it’s sometimes easier to look at the second-hand market. It’s fun to have a bike, but many people keep them in the shed or barn on their property and forget about them.
When you can make a fair offer for the bike, you can snag the carb off of it – and it could be in excellent condition. Just remember to inspect the equipment before finalizing your purchase.
Dozens of bikes have come with PWKs over the years, but the most common ones that could work with your CR125 or CR250 are the following makes and models.
- Yamaha YZ250 2001 and newer with TPS.
- Kawasaki KX250 1998 and newer with TPS.
- Suzuki RM250 1998 and newer with TPS.
- KTM 2-strokes 2202 and newer.
The KTM bikes can be hit or miss. Some of them come with a standard PWK carb, while others have an Air Striker. A third option that measures only 35 mm is also out there.
It’s not just bikes and Motocross that benefit from the Air Striker swap. Some ATVs and Enduros have compatibility with this carburetor.
If you’re looking for ways to enhance power or generate more efficient results, this investment makes sense.
PWK Air Striker Specs to Review
Here’s a closer look at the configurations to consider when reviewing the Air Strikers and Quadvents that come from Keihin NA (which is now part of the Hitachi Astemo family).
| Size | Main Jet | Slow Jet | Jet Needle | Thr. Valve |
| PWK 35mm S65 | 160 | 48 | 48DEK | CA 4.5 |
| PWK 36 mm S63 | 165 | 55 | 48DGJ | CA 5.0 |
| PWK 38 mm S66 | 170 | 55 | 48DDJ | CA 7.0 |
Re-jetting might be required with the PWK Air Striker swap on some bikes. If you’re unsure of what to expect, it’s a good idea to consult with a specialist in this area to ensure the change improves your ride instead of detracting power from it.
The carb itself is lightweight, with a total shipping weight of 1.55 pounds across the board for the three primary sizes.
Symptoms of Fouled Plugs on Bikes
Although you can upgrade to the PWK Air Striker at any time, it makes sense for some bikes to take this approach after the plugs foul.
You can also be proactive with this swap before experiencing any signs or symptoms of fouled plugs.
If you’re waiting until an issue develops, here is what to watch for on your bike.
1. Misfiring Issues
The most common sign of fouled plugs involves misfiring. The bike goes off its normal rhythm when operating, sometimes for a few seconds, before it gets back to the sounds you’re used to hearing.
Misfires occur when a spark plug doesn’t arc at its tip at the proper time. That causes the gas mix to change, throwing off the combustion cycle. It might be challenging to start some bikes with this issue.
2. Backfiring Problems
Fouled spark plugs can cause bikes to backfire. This issue occurs when random bangs or pops come from the exhaust. It happens because the spark plugs produce intermittent sparking.
Backfiring is often intermittent. The bike might seem fine most of the time, but then you get rattled by a massive bang. That’s a great time to consider a PWK Air Striker swap.
3. Fuel Smells
When the spark plugs foul, the leftover fuel in the combustion chamber tends to linker. It can stay there or go past the exhaust valve. You’ll likely detect gasoline odors in this circumstance.
If the fuel gets established in the exhaust valve, it could go through the pipe and spray gasoline while riding.
Before you jump to conclusions, it is possible that water could be coming out of the exhaust pipe due to condensation.
If you typically smell fuel when starting or operating your bike, it’s time to swap the plugs and consider a PWK Air Striker swap.
4. Flooded Engine
Your bike used to start right away. These days, it begins cranking repetitively without any success. If you’ve checked your wires and cables already, the chances are good that you’ve got a plug fouling issue.
This problem often delivers strong gasoline odors. The combustion chamber fills with fuel because it isn’t getting ignited.
Everything else likely works as expected in this situation, including the carburetor and fuel injector, to give you the corrected air-to-fuel ratio.
The fouled plugs stop the cycle from finishing, which means you’re stuck on a giant paperweight until it gets fixed.
5. Plug Malfunction
If you have problems starting your bike and everything seems to check out, a visual inspection of each spark plug could be necessary.
Spark plug sockets come in 5/8 or 13/16 sizing (in inches). Most designs use a rubber insert that holds the part in place firmly. If it’s difficult to reach on your bike, a universal joint could be necessary.
Look for signs of fouling after the plug is removed. The most common problem is a bent or broken component.
If your bike was outside, there could be corrosion or rust stopping the spark from forming. Burn marks create scoring that can interrupt the process in similar ways.
What Are the Benefits of Choosing a PWK Air Striker?
PWK Air Striker carburetors have a reputation for producing power without any compromise. Although they’re most often found in the world of Motocross, the performance this component offers is suitable for any compatible bike. That’s why they’ve become stock on most leading brands today.
When I got into the Motocross world, the first thing that someone asked me involved my opinion of the PWK Air Striker. I remember shrugging and mumbling something about being new before skirting away.
That encounter led me to start researching more about this component. What I found was that five essential features are worth reviewing if you’re looking to make a carburetor swap.
- The throttle bores on the PWK receive sizing that delivers riders a maximum level of power in virtually any environment or situation.
- It delivers simplified jetting with the available components.
- Quad vents eliminate the bogging that happens post-jump when your passages are plugged up with fuel.
- The semi-flat throttle valve is chromed to ensure an appropriate response and improved flow when operating at high RPMs.
- The Air Striker directs air toward the primary nozzle to improve throttle and signal response.
Although I’ve always been the kind of person who charts an individualized route, it made sense to roll with a PWK Air Striker. It helped me maximize my riding experience while delivering results on the track.
