Pro Circuit T-6 Stainless System (2022 Kawasaki KX250)

The muffler on the stock 2022 KX250 sounds a little too blown out for me in stock form (even when new). The tone of the muffler is not pleasant to the ear, so I crossed my fingers, called Pro Circuit and picked up a T-6 (stainless system) Muffler System to see if it enhances the current engine character of the KX250. Ti-6 and Ti-6 Pro systems are tough to get at the moment so we settled on a stainless system, which can last longer (more durable) than a titanium system. While I had a PC system, I thought it would be cool to give you guys a run down on a couple other mufflers that I have tried on the KX250 and compare those with the PC (see below). Here’s what I came away with… 

Immediately I weighed the stock and PC T-6 mufflers and took notice of how the Pro Circuit system cut just over 0.7 pounds off the green machine so we were starting off well. The next thing that made me happy was that the PC muffler goes on easy and literally took me 7 minutes to change out! Boom! So far so good! After installation I recruited my son to help me evaluate the system as he now has a new found love for the KX250 and a Team Green ride that didn’t exist last year. I made him write his notes down and I told him we would compare both of ours after we have tested this muffler at a few different tracks. We tested the T-6 at Glen Helen, Perris, secret dez tracks and State Fair MX just so we knew exactly what we were getting out of the PC system. 

 When you purchase your T-6 muffler it will come with a spark arrester screen already installed inside the muffler. DO NOT REMOVE THIS! This helps with back pressure and gives the KX250 the RPM response and bottom end that Aden (my son) and I both like. When we took it out the PC system lost some excitement down low and lost a little bottom end. You can however punch a small hole through the back of the screen and then reinstall it. Doing this actually helps give the PC system a little more bottom end/RPM response while still retaining that back pressure that is important for rear wheel connection. 

Ok so now that we got the “tricks” out of the way, how does this PC system compare to stock?. Normally I DO NOT get more bottom end with a PC system (versus stock) on any brand of bike, but I was surprised that I got a little extra bottom end pulling power out of the PC system. RPM response is a little softer than the stock system, but when opening up the throttle out of corners the KX250 (with the PC system) pulls harder than the stocker. Mid range is where you will feel the meat of this power. When accelerating out of the corner and shifting to third, the KX250 doesn't have that “empty” feeling that the stock muffler has at times when the track is tilled deep. The PC system keeps pulling once the KX250 is shifted into third gear and continues to pull harder into the top end. Over-rev is as good as stock and I didn’t notice any loss of over-rev when swapping the two mufflers back and forth. 

 The only real negative I have found from the PC system is I wish it would have a little more low end RPM response, like the stock system. The stock muffler has such great initial touch of throttle which can make the bike feel a little lighter when hopping over bumps or popping out of blown out berms. The PC system pulls better out of corners, but is just a smoother initial touch (AKA, low end RPM response). If you want more low end RPM response and could stand to lose some pulling power then take the screen out of the T-6. Doing this will give you more low end RPM response, but will hurt some mid range and it will not sound as good in my opinion.

Overall Aden and I are pleased with the PC system for the 2021 KX250 and I guess we shouldn’t be surprised as they do have that Kawasaki race team and all. My son surprisingly felt most of the pulling power, but didn’t feel much increase anywhere else, so not bad for a 14 year old squirrel. Hey, Mitch! If you’re reading this, good job! Chanceability that he reads this? ZERO. POINT. ZERO! 

Extra Credit: We tried a HGS and FMF system just to see what we had in the Pro Circuit T-6 Muffler System. 

HGS: The HGS has a bottom end feel similar to the Pro Circuit system but not as good as a mid range pull. The HGS system has more top end than the PC and FMF system, but it takes a little work to get there. If I was riding a sand track, I could see how someone could like this system. Great top end-over-rev. 

FMF: The FMF has more bottom end than the PC system and has slightly less mid range than the PC, yet more the than the HGS. Top End is short and over-rev has slightly less. than stock. 

REC Seat Nuts (Kawasaki KX 450/250)

The REC MX Seat Nuts are designed to be an OEM replacement and use the OEM bolts. Chances are if you have a Kawasaki you already have stripped out the threads on the OEM nuts as they are just too soft. The REC Seat Nuts take a little work to fit/press into the rear fender, but once inside the chances of you stripping out or losing them like the stock nuts are slim. The nuts are $29.95 a pair (kind of expensive), but have eased our mind about possibly losing a seat on the track. No one wants to ride back on the track to find their seat and take that ride of shame through the pits. Grab your balls and get some seat nuts! You can go to RECMX.com and check them out.

Pro Circuit Linkage (2021 Kawasaki KX250)

The new Pro Circuit linkage system for the 2021 KX250 and 2019-2021 KX450 gives the KX’s handling performance an entirely different feel. I did this review on a 2021 KX250 because my son Aden was only 125 pounds and needed something plusher for his style of riding. Although I liked the stock KYB suspension, I felt that it was a little empty (soft feeling) on the end stroke. The OEM linkage system for the newer KX models tends to be a little harsh at the beginning of the stroke and gets softer as the rear wheel goes deeper into the stroke. With Aden being lighter, he had problems with the rear end being harsh on small bump absorption and I had problems with the rear end being too soft at the end stroke (or high speed compression situations). With the new Pro Circuit linkage system, it gives the linkage ratio curve what we both need. The Pro Circuit KX250/KX450 linkage system gives the shock a plusher feel at the beginning of its stroke and then stiffens up as the rear wheel goes deeper into its travel. This adjustment could mean that it lessens the need for stiffer high-speed valving, which can cause the rear to feel harsh and deflective. When talking to Pro Circuit, a considerable amount of research and testing for this new linkage system has resulted in a more true-to-weight spring rate, in order to reach the ultimate sweet spot in handling for your new KX250/KX450. 

I wanted to test this linkage for Aden and I on the 2021 KX250 with stock valving as well as a re-valved set of suspension to see what this linkage system can give the rider in feel. With the stock setting and the PC linkage I immediately felt it was too soft for my liking out of corners (the rear end felt too low in the stroke at 103mm of sag), but I found out that Pro Circuit recommends a spring rate increase of 0.2 kg/mm so I wen from the stock 54 N/mm spring to a 56 N/mm with much better results. Now the rear end stayed up higher in the stroke on acceleration and felt plusher on small bump absorption. The stiffer spring and the linkage combined also gave me the end stroke feel that I was looking for. I am the type of rider that DOES NOT mind bottoming out a couple times a lap around the track, but it just can’t feel like I am hitting a ton of bricks when doing so. The PC linkage coupled with the spring rate change still allowed me to use all of the suspension but didn’t give me that harsh bottomed out feel. 

With Aden on the KX250 with the PC linkage, it was even more noticeable change for him because he could leave the stock spring on and the rear of the bike immediately got plusher feeling on small chop. He also mentioned that he could get on the gas sooner because he felt like the PC linkage gave him more rear wheel traction. Normally, being that Aden is only 125 pounds we usually have to go to a softer shock spring, but with the PC linkage requiring a stiffer spring rate, this ultimately balanced the bike out for a 125 pound B level type of rider.  

When tested with a fully re-valved set of Pro Circuit suspension the linkage only gave the rider more of a balanced feel with the sag at 103mm. Riding more aggressive was made slightly easier with the PC linkage as I could get on the gas sooner out of corners (under heavy choppy conditions) because the rear end seemed to stay straighter as well as had more rear wheel traction. For $445.00 this mod is a little expensive for my taste, but it does actually help with comfort and performance on the 2021 KX250. If you’re a lighter rider, this linkage could save you from a spring change and if you’re an aggressive rider, that is slightly heavier, it can help you from getting too low in the stroke under heavy loads without a re-valve. 

If there was one sentence that described this linkage it would be: “Ultimately, this new PC linkage creates a plusher feel while increasing rear wheel traction”. 

If you have any questions about this pinkeye please feel free to email me at kris@keeferinctesting.com 

Pro Circuit Ti-6 Muffler System (2021 Kawasaki KX250)

Over 300 part number changes have been made on the 2021 Kawasaki KX250. After our first day on the new KX250 I was quite impressed with its ability to pull hard out of the corner and rev out longer than last year’s model. However, even though the Kawasaki has improved for 2021, the muffler still sounds a little too blown out for me in stock form (even when new). The tone of the muffler is not pleasant to the ear, so I crossed my fingers, called Pro Circuit and picked up a Ti-6 Muffler System to see if it enhances the current engine character of the KX250. Here’s what I came away with… 

Immediately I weighed the both mufflers and took notice of how the Pro Circuit system cut just over 1.2 pounds off the green machine so we were starting off well. The next thing that made me happy was that the PC muffler goes on easy and literally took me 7 minutes to change out! Boom! So far so good! After installation I recruited my son to help me evaluate the system as he now has a new found love for the KX250 that didn’t exist last year. I made him write his notes down and I told him we would compare both of ours after we have tested this muffler at three different tracks. We tested the Ti-6 at Glen Helen, Perris and State Fair MX just so we knew exactly what we were getting out of the PC system. 

When you purchase your Ti-6 muffler it will come with a spark arrester screen already installed inside the muffler. DO NOT REMOVE THIS! This helps with back pressure and gives the KX250 the RPM response and bottom end that Aden (my son) and I both like. When we took it out the PC system lost some excitement down low and lost a little bottom end. You can however punch a small hole through the back of the screen and then reinstall it. Doing this actually helps give the PC system a little more bottom end and RPM response while still retaining that back pressure that is important for rear wheel connection. 

Ok so now that we got the “tricks” out of the way, how does this PC system compare to stock?. Normally I DO NOT get more bottom end with a PC system (versus stock) on any brand of bike, but I was surprised that I got a little extra bottom end pulling power out of the PC system. RPM response is a little softer than the stock system, but when opening up the throttle out of corners the KX250 with the PC system pulls harder than the stocker. Mid range is where you will feel the meat of this power. When accelerating out of the corner and shifting to third, the KX250 doesn't have that “empty” feeling that the stock muffler has at times when the track is tilled deep. The PC system keeps pulling once the KX250 is shifted into third gear and continues to pull harder into the top end of the machine. Over-rev is as good as stock and I didn’t notice any loss of over-rev when swapping the two mufflers back and forth. 

The only real negative I have found from the PC system is I wish it would have a little more low end RPM response. Like I mentioned that stock muffler has a great initial touch of throttle which can make the bike feel a little lighter when hopping over bumps or popping out of blown out berms. The PC system pulls better out of corners, but is just a smoother initial touch (AKA, low end RPM response). If you want more low end RPM response and could stand to lose some pulling power then take the screen out of the Ti-6. Doing this will give you more low end RPM response, but will hurt some mid range.

Overall Aden and I are pleased with the PC system for the 2021 KX250 and I guess we shouldn’t be surprised as they do have that Kawasaki race team and all. My son surprisingly felt most of the pulling power, but didn’t feel much increase anywhere else, so not bad for a 14 year old squirrel. Hey, Mitch! If you’re reading this, good job! Chanceability that he reads this? ZERO. POINT. ZERO! 

Extra Credit: If you want more pulling power as well as more top end install the “Chavez Map” with your Pro Circuit Ti-6 muffler and thank me later. See below for map..