The riding season is approching and I want to dial in my 22 YZ125 once and for all. So first the bike is hard to start so I need to use choke and really warm it up before the throttle is rideable. Now when ever I rev the throttle fast for the first maybe 1/8ish if not more throttle postition it bogs down and I have to clutch it to rev it up again in order to get it up to rpms. The higher throttle ranges feel fine meaning I can rev it up fast and it feels good. The only issue is the low throttle postion bogging. Anyone have ideas how to fix it once and for all so i have a crispy throttle? Only reason I opened a new thread for this is because now there 2 newer models of the bike with the new carb which people have experiance tuning vs the first few months of the new 2022 redesign. If anyone has any sugestions, lmk. Thanks.
specs
Bike yz125 2022
Around 27 hours on it
Jets:
Pilot - 50
Needle - 3th clip on red needle
Main - 170
Yamalube 2r mixed 32:1 with 91 octane gas
Clean and stock air filter
No exhaust work
br8 spark plugs
Trail riding but go fast (4-5th gear pinned) on the roads for a little to get to the trails)
The best solution for this bike, at least with the stock #7 slide, is to buy the GYTR jetting kit with the Y4 needle and use Pro Circuit's new spec.
62 pilot
165 main
Y4 needle in the 2nd clip pos.
70 power jet
The GYTR kit comes with the 70 power jet. You have to get a 62 pilot separately.
Bro so basically we r out 100 bucks usd plus shipping to Canada cause JD did not have good settings. I’m confused because dirtbiketv recommended them from the start and said it changed it to a different machine and that’s the reason I bought it (early 22 yz not much information bout the bike yet) but from what I’m reading everyone is having similar problems with the jd kit. Is it recommended to change the power jet?
also is the pro circuit jetting recommended for trail use too? Also do u have the P/N for the Y4 or Y3 needle. I have the numbers for the 70 power jet and the 62 Pilot. It just dosnt make sence spending 100 dollars usd on 2 jets
No one but you can fix this issue, your bike is struggling with how YOU ride it, it’s a MXER and jetted to be held WIDE for 10-30 minutes straight for a moto, after that not much, for jetting on trails You go leaner on the pilot for low end, and the main can remain rich if you need to open it up, however this can cause a bog in its own right, learn how to jet, buy a kit, and run the bike for hours on end, bring jets to the trails with you, if you rich foul a plug? Lean thw pilot, lean foul? Go up a size, and the br8? Is that an es? Or did you get an iridium plug?
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The only way to get the Y4 needle is to buy the Yamaha kit (which also includes the 70 power jet) B4X-CARBS-KT-10. Partzilla has it for about $40.
I bought the JD kit first as well and was not happy with it. Then I bought the Y3 needle kit last year and it's good but not 100% perfect. So I can understand spending more than you'd like to get the jetting right on these bikes.
Try moving the clip down to the 4th position on the red needle (richer). Also, try fine tuning your air screw for better off-idle response. How many turns out are you currently set at?
I assume your kit has a BLUE needle, so try it in the 4th clip. What is your air screw setting?
If you're doing 5th gear pinned on roads for extended periods with the BR8 and it hasn't seized, then your main jet must be pretty good.
Es
Wdym not seized. The bike runs mint only thing is the bog
I originally moved it leaner to deal the with plugs fouling
So my bike runs mint besides the bog and to fix that I’ll try adjusting the needle clip and air screw. Do my other jets seem good ? From what I can tell they r.
JD Jetting recommends a 45 pilot...
I don't think this is for a powerjet carb. The 22' yz125 has a different table with the 50 pilot and 170ish main at sea level
Good point, 50 still seems rich.
I've jetted a few of these newer YZ125's using the JD kit. I ended up on Red-4 and 50/172 and they all ripped with no bog. I was using 40:1 with Motul 800 and pump gas.
What alt and temp?
sea level to 1,000 ft, 60-85 degrees.
Pit Row
I’ll try that, I use Yamalube 2R and mix with 32:1. I don’t know why but I’m scared to mix 40:1. Is yamalube generally similar specs as motul800 in terms of flash point. I’m kind of new to this and just need some re assurance that 40:1 is safe and won’t blow my bike up. I mainly trail ride but need to go fast on the roads for 10-15 mins to get to trails
Motul 800 is a much higher flash point than Yamalube, yet it burns very clean. It is an excellent oil. I am not a big fan of Yamalube. For trail riding, you can even use Motul 710. It is also an excellent oil but more suited to trail riding than 800.
40:1 is plenty of oil (if using a high end synthetic), especially for trail riding. As another benefit, I think you are slightly lean on your settings (hence the bog) and going to 40:1 has the side effect of also slightly richening the jetting (more gas, less oil).
If you are riding long stretches of road, you cannot simply hold the throttle open on a 125. MX bikes are not intended for this type of riding, especially small bore 2-strokes. You need to cruise easily below the powerband and alternate on/off throttle regularly.
Ok I’ll try this, what made u use the settings u suggested? Did u experience a similar thing as me? And u think ur settings r good for trails too? I assume u ride mx
JD recommend
50 P
Red 4
main 170
The settings I used worked excellent for MX. Bikes were very crisp so would have been fine for trail also. Jetting over the internet is hard, so you are going to have to dial in for your specific conditions based on trial and error.
Thanks for ur help, but one more thing, why did u choose to do 172 instead of the recommended 170 at 0-1000ft alt?
Oh lol I missed that. So I guess my solution is to switch to 40:1
does anybody have a part number for the 70 power jet or a link to buy it online?
Yamaha 4JT-1494F-15-00
Or see all sizes here. https://www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_N424-52_l…
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