Tuned: Jay Clark's 2021 Yamaha YZ250 Rebuild

2021 Yamaha YZ250 Rebuild

Story by Trevor Hunter, Photos by Trevor Hunter, Jerbal Shots

Jay Clark is no mystery man in the motorcycle industry – he builds more bikes than anyone and is a helping hand to all of the motorcycle media. As he does every so often, he called asking about a bike build and the moment he said YZ250, there was already a resounding yes coming from our end. Jay’s bikes are solid – they’re built well using quality parts that aren’t out of the ordinary and almost always work, and they typically look as good as they perform.

Here is where a ‘21 Yamaha YZ250 two-stroke enters the chat. Jay’s friend had bought this YZ new just before the redesigned 2022 YZ dropped in 2021. With it in his hands, he had planned to make it a big bore YZ and spent years chasing a better performing YZ than stock. Alas, he finally settled on putting it back to stock. With every part imaginable at his fingertips, he enlisted Jay to help him restore the YZ to its original glory and get it running right. There truly isn’t a lot done to this bike to increase performance. Most of it is put back to stock spec using Jay’s vendors like Wiseco, Cometic, and Pro X, but there are still a fair share of mods coming from Rekluse, Moto Tassinari, FMF, and more. We spent some time riding the Yamaha at Glen Helen getting a feel for the classic smoker and with all of the time we’ve been spending on two-strokes in the last year, it was good for some comparison.

The YZ engine is realistically 20+ years old in design, but it still performs on the motocross track. It’s responsive, has good hit, and puts out power across the board. With the FMF Factory Fatty/Powercore 2 combo and V-Force Reed Cage, the initial hit is tamed down from the stock ‘21 and older spec, and carries further into the top end where the bike revs out more like a carb Austrian two-stroke from just a few years ago.

The powerband is easier and more friendly to ride with this spec, and feels more similar to how the ‘22+ YZ’s run with the redesigned airbox altering the power delivery (we feel in a good way). I typically run a shorter silencer for a harder hit and more bottom end, but the Powercore 2 was a nice touch in making the YZ engine easier to ride. Sticking to the 14/50 Pro X gearing is adequate on the MX track and we felt the shift points were spot on and smooth with the Rekluse Torq Drive clutch plates.

Yamaha has had the suspension game dialed for years with KYB’s SSS spring components for years on all of the bLU cRU models and it’s tough to not nail a good setting early on with the tried-and-true system. JBI rebuilt and set up the KYB bump sticks and despite not being set up for us, they handled quite well. We set the sag at 105mm and hit the track with no changes needed throughout the day. We felt a little harshness out of the fork when we were meandering around the track, but once the intensity increased slightly and we got up to speed, the suspension had good hold up and felt very balanced and comfortable. We had good edge grip most of the time (more on this later) and didn’t suffer from an unsettled bike at any time.

Like the rest of the bike, the YZ250 chassis is proven and we like it. It’s stable, predictable, and handles well nearly anywhere we may take it. There really aren’t any chassis mods to speak of on this bike, but we don’t feel it needs any as it already handles so well in stock trim. The Works Connection Clutch Perch offers a smooth and easy pull at the lever with a nicely shaped lever – one of our favorite mods to any bike with a cable clutch. The Moto Seat Seat Cover with ribs was welcomed with the added traction and grip that the ribs provide while still maintaining a good level of comfort with no chaffing. The ODI bar bend was very neutral, but one “gripe” I have is I don’t particularly enjoy lock-on grips for the harder feel and slightly more vibration through them. So many of our testers love the ODI and Emig V2.0 lock-on grips, but I still prefer an old-school rubber grip just like I prefer a cable clutch over a hydraulic option.

Another small change I would’ve liked to make would be to run a different front tire. The MX34F front tire is a little unpredictable at times for me, and the AT82F front tire is my favorite tire that Dunlop makes and is one of my favorites on the market of any brand. It’s predictable and has good performance across a variety of conditions.

Having spent a fair amount of time on Beta, KTM, and GasGas two-strokes over the past year, it was refreshing to jump back on this YZ to feel how it stacks up to bikes that have undergone change in recent years. The YZ engine is the most lively and exciting of the bunch. That’s not to say it’s better or worse, just different. It makes good power across the rev range, has a crisp throttle response, and is more playful than any of the other engines that we’ve been riding. However, it isn’t as forgiving if you miss a shift or are in too high of a gear when cornering. It doesn’t quite have the torque to build RPMs quickly when a mistake is made. Likewise, the lack of a counter balancer equals more vibration than the newer Austrian models, but similar to a Beta in terms of how much you feel through the bars and pegs.

The lack of an electric start system and battery leads to a lighter scale weight and that’s felt when riding, but it is nice to have those features on the other bikes. In terms of this, you have to weigh simplicity and lightweight vs function and technology and what is more important to you.

Jay’s rebuilt YZ250 project bike didn’t disappoint and we had a blast ripping it around Glen Helen for a day. After riding this, the cockpit feels more dated with a dip in the seat versus the newer model with a flatter and modern seat profile, but it was still fun nonetheless. There are more shiny parts than performance oriented parts on this build, but that’s due to the solid base platform that Yamaha has in the tried-and-true YZ250.