Well, we finally got our hands on a new 2022 yz125 for some initial baseline dyno runs. The owner of the bike also has a previous generation yz134 we built for him which has become his favorite bike in the stable of 250f's, 350f, and 450f. The owner is in his 60's and loves to ride with his sons - and has found the little bore 125 based machines to be the most fun and safest to keep riding year around.
His comments on the 2022 yz were that it could use a little more bottom and pulling power out of corners, but he felt the top end and over rev was fantastic. He also stated both he and his sons felt the changed ergonomics made the bike handle much better than the previous year bike - I'd bet the stiffer suspension settings for 2022 helped in that role a bit (as the older model is quite soft by modern standards)
Lets get to the video - if you haven't seen it, it's attached below.
His comments on the 2022 yz were that it could use a little more bottom and pulling power out of corners, but he felt the top end and over rev was fantastic. He also stated both he and his sons felt the changed ergonomics made the bike handle much better than the previous year bike - I'd bet the stiffer suspension settings for 2022 helped in that role a bit (as the older model is quite soft by modern standards)
Lets get to the video - if you haven't seen it, it's attached below.
Now, Let's move on to some dyno charts. We did a huge amount of testing - most of which isn't shown in the video. But we found the bike is jetted a little rich most specifically on the pilot and needle. The main jet is actually close for pump gas - but has room to go leaner for more power with race fuels.
The stock jetting we had on our USA spec bike was
75 pilot
160 main
2nd clip on stock needle NYDF
While I think there is more time we will spend on the jetting - we tested from 65-75 and found that it developed a lean bog around the 68 needle unless we had the air screw at 1/2 turn from all the way in.
I've seen reports online of people going to more "normal pwk" settings with a 50-55 pilot and 175 ish main. But we repeatable lost power going richer on the main - and found the low end running quality deteriorated dramatically below a 65 pilot. Jets add to each other, meaning if you went to a 50 pilot and a 175 main - it wouldn't be as rich as a 75 and 175 - the pilot wont contribute as much fuel at a 50. Something to keep in mind is the is a powerjet carb - which adds fuel to the main jet circuit. If the powerjet were plugged, the main would need to go to around a 185-190 to run right. I highly suggest you keep the powerjet system - it improves midrange power without hurting over rev.
The stock jetting we had on our USA spec bike was
75 pilot
160 main
2nd clip on stock needle NYDF
While I think there is more time we will spend on the jetting - we tested from 65-75 and found that it developed a lean bog around the 68 needle unless we had the air screw at 1/2 turn from all the way in.
I've seen reports online of people going to more "normal pwk" settings with a 50-55 pilot and 175 ish main. But we repeatable lost power going richer on the main - and found the low end running quality deteriorated dramatically below a 65 pilot. Jets add to each other, meaning if you went to a 50 pilot and a 175 main - it wouldn't be as rich as a 75 and 175 - the pilot wont contribute as much fuel at a 50. Something to keep in mind is the is a powerjet carb - which adds fuel to the main jet circuit. If the powerjet were plugged, the main would need to go to around a 185-190 to run right. I highly suggest you keep the powerjet system - it improves midrange power without hurting over rev.
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