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Carson Mumford's Factory Pro Circuit Kawasaki KX250

Oct 21, 2023

Pro Circuit and Mitch Payton have had a rough go at racing the past couple years. The main players for Pro Circuit 250 squad were injured in both coasts this season so the team had to go hunting for replacements. Carson Mumford was on Mitch's radar and picked up to fill in on the west coast series. We met up with former racer and now mechanic Tony Archer to go over easily one of the most trick bikes in the pits. Mitch Payton and the crew at Pro Circuit add their touch to every inch of the Kawasaki KX250. Let's get into the details!

Carson is running Renthal 996 handlebars up front on his Kawasaki KX250.

You can see in this photo that Carson is using the Renthal soft half waffle grips with grip donut. Tony still uses grip glue even though they are wire tied. He likes to have the added insurance and keep the grip in place no matter what. Carson is also running the Pro Circuit billet throttle tube which anyone can buy over the counter from Pro Circuit for their personal bike.

ARC break away levers are used on the brake and clutch for Carson's bike. On both levers he runs them a smidge down but really neutral overall. Interesting to see where taller riders like Carson to position their handlebars and levers for racing. This is a stock front brake master cylinder but it is off an older model. We have seen this before in the factory paddock. The older master cylinder offers a larger piston and fluid capacity. The team would rather some added stopping power up front. Faster riders rely heavily on the front brake system and not much on the rear.

The brake lines are stock but the team does cut some of the sheething off them for weight and adds heat shrink to combat water entering this area of the motorcycle.

You can see on Carson's clutch master cylinder and lines that there are carbon covers protecting them. This could easily end a race if this part of the bike was damaged so the teams adds this protection on there for durability.

The kill switch is stock but the entire area of the handlebars has been simplified to avoid any issues or getting hit. You can see that they move the kill switch inward on the handlebars to protect it even more. The start button has a housing added by PC to prevent Carson from actually bumping it during a race. Riders like Carson lean over the bike and can accidentally hit the buttons with their chest or body. You can also see that the start wire has been beefed up to prevent water or debris interfering with starts.

Something that caught our eye was the buttons located on the left side head tube. This is where Tony and the team have placed all the start map buttons. This actually places the buttons much closer to where the actual connection is. It also takes a lot of clutter off the handlebars by place them here. There is some added epoxy on the buttons to keep the water out as well.

Pro Circuit triple clamps. These are the same triple clamps you can buy for your KX if you wanted to. Carson is a taller rider but doesn't go too crazy with his bar mounts. It is standard height but the team does have options if their rider prefers to lower or higher. The steering stem is firmly tight but not super tight like on other factory bikes in the paddock. Tony Archer has a torque spec he sticks to and does it every time the bike is built for racing.

SHOWA/Pro Circuit suspension is mounted to the front end of the motorcycle. Pro Circuit has a SHOWA technician dedicated to the race team and helps with R&D. It's no surprise that all Supercross suspension is super stiff but the team is looking for that happy balance. They want it stiff but also that plushness feeling at the initial part of the stroke to gain a better feel in the hands.

A factory Nissin caliper with Braking front rotors are used on the PC250. The Nissin caliper is factory because it utilizes smaller/thinner pads which is only for Supercross use. It's really more of a weight thing then anything. The team won't run this setup for outdoors. You can see the full coverage carbon disc guard on Mumford's bike. This guard protects the entire brake system on the wheel as well as acts like a ski. When the bike goes into deep ruts the guard can glide through instead of getting hung up by the caliper.

The front axle on the bike is titanium. The team has options but we’ve seen Pro Circuit run the titanium for several years now on the KX250. You can see the titanium pinch bolts on the axle lugs as well in this photo.

Excel A60 rims with KHI (Factory Japan Kawasaki) hubs are used.

The front tire is a Dunlop spec tire that will eventually make its way to the consumer level. The team has a few options to choose from and right now Carson is on the latest that they have to offer. Tony mentioned to us that once Carson found this tire there was no reason to switch around. A lot of the factory riders linger around one front tire pattern for racing and rarely switch it up. Eli Tomac ran the same pattern front tire for 3-4 seasons without changing!

The team is running a 1.8 radiator cap which is off a KX85. There is a pin inside the cap to avoid the rider spinning it off with their legs when cornering. You can also see the hoses to the catch can which is tucked under the shroud. The catch can traps the hot coolant and instead of it blowing out the bottom hoses it is recycled back into the radiators once it cools off. This avoids loss of coolant and provides efficiency to the entire engine/radiators. The team also has larger temp caps if need be.

The radiators are oversized on the Pro Circuit Kawasaki KX250. They do have a built in oil cooler and are Martin Radiators. They are welded and supported for durability purposes. On the left side of the radiators you can see the titanium bleeder that's been added.

We noticed that there were carbon extensions added to the shrouds on the bike. Riders with long legs like Carson Mumford will sometimes get their boot or knee braces caught on the shrouds. This extension helps from that ever happening and adds some insurance for the rider/team.

The team is running data on the motorcycle at all times. This red nosed device is the logger that records everything the bike is doing and features GPS. The mechanics, team, and rider can go over the bike after every single session. They can make changes based around rider feedback and this data acquisition shown above.

A Pro Circuit holeshot device is used on Carson's race bike. It is a two button system. The top bottom isn't used very often. With the addition of Supercross metal grates the team runs it as deep as they possibly can. They do have a fork guard brace underneath to help prevent the fork guards from being ripped off as the holeshot device lets loose.

Works Chassis LABs provides both the front and back engine hangars for the motorcycle. They are titanium and offer a few different options for the team. Carson is on the "standard" for his set up. Titanium nuts are also added to the bike. This can change the flex characteristic of the bike on track. They also help with weight reduction. 7lbs+1 horsepower and power is king in the 250 class. Teams will do whatever it takes to shed some lbs on their bikes.

The meat and potatoes. The Factory Pro Circuit Kawasaki KX250 engine. Pro Circuit is the only team that has their mechanics still build the engines. Tony Archer and his other teammates actually break down the entire motorcycle themselves. Build day means a lot more to the mechanics at Pro Circuit and they take pride in their work. It is also a lot of responsibility for a Pro Circuit mechanic like Tony Archer to take on. It is up to them that their rider will have a fast but safe motorcycle to ride each weekend while competing. All of this is done in Corona, California. A large majority of the components in this engine you can buy for your KX250. There are some secrets that the team only uses but for the most part you can buy this. You could send your engine into Pro Circuit and have someone build you a Pro Circuit race horse. You can also see that the primary cover is akadized. This helps with durability and heat dispersion.

This is a custom Pro Circuit clutch cover that the team designs in house. You can also see the oil pump that you can buy for your KX250. The team is running Hinson components with stock plates. They are also using the Pro Circuit clutch springs. It is a pretty hard hitting clutch. The team needs something to grab hard in the whoops but you also have to have it soft enough to be able to handle it off the start.

On the brake pedal you can see the team is using a brake snake. This is made from an old clutch cable. It keeps the brake pedal from getting pulled outward by debris or tough blocks which in turn will cause brake failure. The brake pedal itself is an SR part with folding tip on it.

In the event of a crash or problem with the main start button there is an auxiliary start button added to the bike. It hides behind the shroud and very protected from the outside. We almost missed it when scouring the bike for goodies. The team used to run it back further by the airbox last year.

Items like the ignition cover and timing plugs (in red) you can buy right from Pro Circuit for your motorcycle. Check out the hose routing for the Pro Circuit radiators. It is custom routed through the skid plate and keeps it in place. You can also buy the CMI shifter shown in the photo above. Carson is running the standard shifter and shifter tip. The team does have options but even with Carson's larger feet they keep it standard. You can see the full coverage skid plate protects both sides of the motorcycle extremely well. This carbon skid plate is outsourced and provided to the team for racing.

In this photo we can see the carbon case saver that Pro Circuit is using. This product is also made in house at the shop in Corona,California. It is bolted on with aluminum bolts to in the event the chain does come off the case saver will shear away and the chain will have room to go by without getting jammed up. This is also a good look at the swing arm pivot which is titanium. You can see the plug on the end to keep mud from getting trapped in this area.

On the flip side of the swing arm pivot you will see this brake pedal stop built into it. This stop will prevent the brake pedal from getting shoved too far upwards by something, which will cause the guts of the rear brake master cylinder to be pulled out. This is a preventive measure for the team to ensure there is a small chance of rear brake failure during the race.

Vibram grip tape is used on both sides of the motorcycle. We have only seen this brand of tape used by Pro Circuit Kawasaki. It comes pre cut and lasts quite a long time before needing replacement.

The foot pegs are designed in house at Pro Circuit. Same with the mounts. They have stock springs with titanium pins. You can see they are placed in backwards compared to stock so the mechanic can remove them quickly on race day if need be. The cotter pin can get damaged underneath the footpeg so this is another insurance measure done by Tony Archer. To keep mud from packing into the springs Pro Circuit adds this titanium peg armor covering the area. This is another item designed and made in house at Pro Circuit.

The team designs and runs their own air boots on the KX250. This is a big part that Mitch Payton and the crew work on. The team is now on their 6th generation of this airboot. The team builds the engine to the spec they like and then they fine tune it with the air boot. The air boot plays a large role in the power department on the KX.

An SRKX450 subframe is used on Carson's KX250. The pipe mount is actually beefed up on the SR oem models from Kawasaki. Pro Circuit prefers to run this instead of the standard version to add some durability to the mounting point on the Pro Circuit exhaust.

Twin Air provides the air filters on the Pro Circuit motorcycle. You can see the team is cutting out the panel to provide more air flow to the intake. It is a thinner supercross filter and it is bolted in with a titanium fastener instead of the plastic one that comes stock on the KX250.

Pro Circuit adds this extra guard on their exhaust for durability. Riders can squeeze the exhaust so hard (eg Malcolm Stewart) that they can actually dent the pipe in with their legs. Also riders get hit quite a bit during the start and the pipe can get damaged. Pro Circuit reinforces their exhaust to avoid any major issue on track.

The team is running data acquisition at all times on the bike. You can see the 02 bung on the exhaust which gives the team information on the air/fuel info while the bike is running.

Samco hoses are used on the bike and they will tailor the hoses to the teams’ needs. You can see that the hoses all have oetiker clamps on them. The team doesn't want to risk anything coming loose during a race. They are cut.removed, and replaced every weekend. Let's get to the real reason we are using this photo. The electric water pump has been added to the PC KX250. The team was on the fence at first to switching to this system but after testing they found a clear advantage. This was an obvious no brainer after seeing they dyno charts and increase in power.

The rear master cylinder on Carson Mumford's bike is a factory Nissin. This does not have a window in it. Rocks or debris can damage the window causing the fluid to seep out. The team knows its full and works on the bike enough to not need a window. The clevace they are using is also made by Pro Circuit with titanium hardware attached.

RK chains with standard master link with Renthal sprockets are used on the rear end of the motorcycle. The team is running a 13/49 combination and don't play around with gearing too much because of wheel position. They test the bike with the wheel where they want it and will tailor the engine to work with this gearing. The team is also using their carbon Pro Circuit chain guides which you can buy at their shop or online. You can see all the dimpling and machining done to the rear axle in this photo. Pretty cool! The sprocket is also utilizing titanium sprocket bolts shown in the photo above.

Pro Circuit is also running a titanium rear axle on the motorcycle. The axle blocks are also another item that Pro Circuit designs and produces in house. PC also runs a cotter pin which is very rare to see on any bike in 2023. You can get a good look at the SR factory brake hangar that is made out of billet in this photo also.

Excel A60s, KHI hub, and spec Dunlop tire are used on the Pro Circuit race bike. The team doesn't mess around 120 rear tires. The 120 can provide a larger footprint but it can also rob the bike of power and that's a no go in the 250 class!

A rear Braking rotor is used on the back end of the bike. You can also see the caliper has a carbon protective piece to help avoid debris or issues on the race track. The carbon guard is designed by Pro Circuit.

The rear brake caliper is something the teams works with a lot. The rear brake piston is coated to reduce friction and holes drilled into it to disperse heat. On top of the caliper there is also a hole drilled out to disperse heat as well. The brake pads and brake line is stock.

A SHOWA A Kit rear shock is used out back. You can see the shaft has a cool bright green coating to reduce friction. The team does chassis height on the bike and shortens or lengthens the shock to keep the chassis height the same every time the bike is on the track.

Pro Circuit linkage is used as well. A lot of these components you can purchase for your KX. Pro Circuit works with the SHOWA techs to find a linkage ratio that they want to run on the motorcycle.

Throttle Syndicate provides all the graphics and seat cover for the motorcycle. Carson doesn't have a preference on seats like some of the other riders do in the paddock. GUTS light weight seat foam is added to the bike.