minorgod
Member
- Oct 11, 2009
- 4
- 0
Greetings,
I'm new to motorcycle maintenance and recently bought a used YZ125. It runs pretty well with a new spark plug, but is constantly fouling the plugs and it doesn't like to idle for very long without stalling. Also, it was very sputtery in the middle of the power band particularly in 2nd and 3rd gears. The bike will keep starting fine once it's warmed up, but if it sits overnight it won't start again without a fresh plug or a LOT of effort. After reading the maintenance manual, I adjusted my pilot air screw to about 3 turns out and that seemed to smooth out the sputtering problem, the idling problem, and it seems to have helped the plug fouling a tiny bit, but I'm still fouling them after only 30 minutes of riding. I do seem to get more power from my engine after adjusting that pilot air screw, and the bike really seems to run great now other than the plugs fouling every time I ride. So last night I lowered my main jet needle by 1 notch and I'm going to take it for a test this afternoon and see if that helped. I'm also thinking that I might need to go to a hotter spark plug or maybe change the main jet needle to something slightly larger? I called the dealer to see if he could identify my current jet needle by the numbers (6CHY53-75) and he said it sounds like an aftermarket jet needle. Those numbers don't correspond to any of the standard sizes I've seen in the manuals, but it seems like the numbers on the needle suggest that this needle will give me a very rich mix and if changing my current needle position doesn't do the trick then maybe I should step up a size or two? Any suggestions? Anyone know where my current 6CHY53-75 needle might have come from?
I'm new to motorcycle maintenance and recently bought a used YZ125. It runs pretty well with a new spark plug, but is constantly fouling the plugs and it doesn't like to idle for very long without stalling. Also, it was very sputtery in the middle of the power band particularly in 2nd and 3rd gears. The bike will keep starting fine once it's warmed up, but if it sits overnight it won't start again without a fresh plug or a LOT of effort. After reading the maintenance manual, I adjusted my pilot air screw to about 3 turns out and that seemed to smooth out the sputtering problem, the idling problem, and it seems to have helped the plug fouling a tiny bit, but I'm still fouling them after only 30 minutes of riding. I do seem to get more power from my engine after adjusting that pilot air screw, and the bike really seems to run great now other than the plugs fouling every time I ride. So last night I lowered my main jet needle by 1 notch and I'm going to take it for a test this afternoon and see if that helped. I'm also thinking that I might need to go to a hotter spark plug or maybe change the main jet needle to something slightly larger? I called the dealer to see if he could identify my current jet needle by the numbers (6CHY53-75) and he said it sounds like an aftermarket jet needle. Those numbers don't correspond to any of the standard sizes I've seen in the manuals, but it seems like the numbers on the needle suggest that this needle will give me a very rich mix and if changing my current needle position doesn't do the trick then maybe I should step up a size or two? Any suggestions? Anyone know where my current 6CHY53-75 needle might have come from?