Posts
6
Joined
1/23/2025
Location
Yelm, WA
US
I bought my son a new YZ65. It runs great, starts first kick but if you open the throttle too quickly it bogs. It is worse when cold and improves with the choke on. I have tried moving the needle clip down and I have gone up and down on the pilot and main jets an nothing seems to help. Anyone have experience with these? Here is a clip of the issue.
https://youtube.com/shorts/ccQc0ao_rK8?si=2nzy15tbS0m8O0lP
Its a known fact that a bone stock yz65 needs a 50 pilot. Sounds like you may even need to go to a 52? Especially if the choke improves it.
My notes from my grandsons YZ65 days were a 135 main jet, 50 pilot jet and two turns on the airscrew. Didn't make any changes to the needle. That was on a 21 YZ65, not that they've changed.
Try the richer pilot jet. Are the temperatures cold now? If so you probably want to go one richer on the needle clip as well.
I'm surprised your 25 is lean. Our 24 YZ65 and other new KTMs (50, 65) in the past were ungodly rich.
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The pilot jets specifically? Like I mentioned, yz65s pretty much all need a richer pilot to fix a lean bog issue
I don't think I changed the pilot. I know I dropped the needle to 1st clip and downsized the main 2 steps. Running 91 nonoxy pump gas, motorex 2t 50:1.
50 pilot, 135 main, needle clip 2, 93 octane and 50:1 dominator. Itll be a new bike. The air screw is VERY important on this bike, tuning it correctly will yield massive gains, the carb is a bit large for the engine but it works well when tuned correctly. Set your carb up this way and youll never have an issue. This is for sea level altitude and pump gas.
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