HSR Kumamoto is host to the opening round of the All Japan National MX Championships this weekend.

The All Japan National MX Championships kick off this weekend in Kumamoto, Japan, and our man on the scene, Taku Nagami, got a sneak peek at a couple of the bikes as the teams set up their pit areas on Thursday. The factory Hondas of IA1 Champion Akira Narita and IA2 Champ Toshiki Tomita look production-based at first glance, but a keen eye can spot some differences and plenty of trick parts.

Masahiro Ito tunes Tomita’s works CRF250R. Masa should be familiar to many American race fans, as he worked for several years in the United States as Jason Lawrence’s mechanic and also as a suspension technician at enzo racing,

Tomita’s CRF250R boasts all the factory bike parts like the hand-made titanium fuel cell and works titanium mufflers, but the most interesting aspect of the bike are the works Kayaba PSF2 forks that grace the front of the bike. Is the ’15 CRF250R slated to come outfitted with KYB Pneumatic Spring Forks? We;d assume so. No word just yet on the differences in the PSF2 fork…stay tuned.

The works Honda CRF450R of eight-time All Japan MX Champion Akira Narita is a work of art. Narita is said to prefer a punchier powerband than stock, and that’s just what his factory engine delivers. Unlike the production CRF450R which routes the header pipe out the left side of the cylinder and around the front of the bike in order to gain extra header length, Narita’s machine has a fatter exhaust that exits the right side of the cylinder and routes rearward towards the dual mufflers. Factory Showa suspension graces both ends of the number-one machine. Narita prefers the feel of the traditional mechanical spring, and does not run air forks on his race bike.

The titanium mufflers on Narita’s bike feature carbon fiber end caps. Made in house by Honda/HRC, the cans closely resemble those sold by FMF. 

The factory titanium header pipe on Narita’s bike is a work of art. The waves in the design are both designed to add overall header length, as well as tune the exhaust pulses being routed out the twin mufflers.

This is Yu Hirata’s factory Yamaha YZ450F. Based on a production bike, the machine still has many factory parts, including a radical set of factory Kayaba suspension. Look closely at the rear of the bike and you’ll notice that the shock has a very different reservoir, which is positioned at a 10 and 4 angle, rather than straight up and down. Were digging to learn more about the suspension component, and what benefits it yields.

Sound restrictions in the MFJ are as stringent as ever, and the bikes raced in Japan are quite often as quiet – or even more so – than stock. Check out the beautiful titanium muffler on Hirata’s bike. Also, check t he previous photo of the factory Yamaha to see the varying pipe diameters of the exhaust header as it wraps around the cylinder.

Stay tuned for more from Kumamoto, as today (Friday in Japan), bikes go through tech inspection before the weekend’s activities, and Nagami will check in with even more spy photos!