Testing Grounds- 2020 YZ85 Bike Build


I don’t know about you, but I love the process of little by little modifying a dirt bike to not only make it better but also to cater it to a certain type of rider. At the end of the 2018 season, my son was ready to make the jump from a 65cc machine to a bigger and more powerful 85cc machine. For those parents out there who have either been in the same situation or are preparing to go through it, this can be a challenging transition. In most cases, when a young rider is ready to go from a 65cc to an 85cc bike, they might be age-appropriate, but not quite tall enough. How many times at the track have we witnessed kids out there riding an 85cc for the first time? And while those young riders have no issue with the clutch, gears, or added horsepower, the bike appears to be big for them. As I mentioned, we were in this situation as when my son was ready to move up to an 85cc he was 11 years old and still fairly small.

For this reason, we began looking at the Yamaha YZ85 as a possible bike for him. As far as 85cc bikes go it’s a tad smaller than say a KTM or Kawasaki, so when he sat on it the YZ just seemed to fit him better. Not only could my son touch the ground (on his tippy-toes), but the distance from the footpegs to the top of the seat was shorter, this gave him better leverage to maneuver the bike around when standing up. I also spoke to a few people who had owned a YZ85 previously and they had nothing but good things to say about both the reliability, as well as the bike’s overall performance. With Yamaha introducing their Power Valve technology to this model for 2019, it would bring the horsepower output up to the level of its competitors. So we decided on the YZ85 for the 2019 race season and it ended up being the perfect bike for my son’s first year in the 85cc class. In fact, we were so happy with it that we bought another one for the 2020 season. But with my son being a little, heavier, and more experienced, we knew we needed a few upgrades.

The first item we addressed was in the suspension department and thanks to MP1 Suspension and Krooztune Suspension products from Australia, they took care of that. To add a little more horsepower to the already potent engine, I went to see my old trusted friend Chris Bondi at Bondi Engines for some cylinder porting. We also added an FMF pipe and silencer which worked in unison with the Bondi Engine ported cylinder to increase and broaden the powerband. After that, we finished our YZ85 off with a taller Guts Seat, a few GYTR odds and ends, and a personally designed Decal MX graphic package. During the season we kept up a strict maintenance schedule with oil changes every week, constant greasing of bearings and moving parts, and of course fresh top ends every couple of months. We also had some help along the way from St. Onge Recreation, Pirelli Tires, as well as Steve Simms. The two years my son spent on the YZ85 were excellent and the bike served its purpose as a great introductory bike to the 85cc class. Now we’re onto the Supermini class and a different brand, but before the snow flies and the ground freezes, here is how we built a competitive and fun to ride Yamaha YZ85.

To improve the suspension package on the YZ85, we contacted Mike Parliament at MP1 Suspension and the folks at Krooztune Suspension down under in Australia. For the past few years, Krooztune has been manufacturing key suspension components for bikes like the KTM 50/65, as well as the YZ65/85. For this project, Krooztune sent us their full suspension upgrade kit which included, a bottoming system for the front forks, a new compression piston for the forks, a high-speed compression adjuster for the rear shock, as well as an alloy lock ring for the rear shock. Krooztune has some great products, and between them and MP1 Suspension Services in Ontario, we were able to get our YZ85 set-up perfectly. These modifications not only stiffened up both the forks and the shock but also improved the rebound damping and the overall balance of the bike. Whether you want to use these products from Krooztune or just have your suspension re-valved by Mike at MP1, you won’t be disappointed. Here is how you can contact both companies. (www.mp1suspension.com and www.krooztune.com)

For years, Bondi Engines have been doing engine modifications for everything from dirt bikes to snowmobiles, to go-karts. Chris Bondi knows his stuff and for the YZ85 we had a few options to modify the engine. What we decided on was just some simple porting to clean up the flow of fuel in and out of the cylinder. This gave the engine some added horsepower without us having to run expensive race gas every time we started the bike up. As I said, Bondi could’ve done more to the cylinder and head, but we wanted to keep it simple for this bike. We also added an FMF pipe and FMF silencer to increase and smoothen out the powerband. Both of these modifications worked amazing and improved the performance of the YZ85. You can reach Bondi Engines at www.bondiengines.com and FMF Racing at www.fmfracing.com.

With my son getting taller by day this year, we searched around and found that Guts Racing made a taller seat for all of the 85’s. This ended being the perfect solution to compensate for my son’s growth spurt this past summer. Guts Racing has seat foam and seat covers to fit any rider’s needs and wants. Please visit their website at www.gutsracing.com.

Finally, we purchase a few very cool looking GYTR Products from Yamaha Motor Canada, including a clutch perch assembly and a clutch basket cover. Both products not only looked better than the stock ones, but they also improved the performance and overall reliability of our YZ85. As icing on the cake, we contacted Decal Works (www.decalmx.com) for some customized graphics and number backgrounds. This was a fun project and it not only made our bike work better on the track, but it also made the moto-dad in me feel more reassured that my son was riding a reliable bike. The companies I mentioned in this story have products for all brands and all sizes of bikes, so there’s something for everyone. Whether you’re a young rider or a vet rider, all of you can benefit from making a few key modifications to your bikes. For any questions please reach out to me at chris@mxpmag.com.