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Yz 250 jetting chart


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Hi guys, i found a jetting chart a while ago here. I lost the file when i got a new computer. I searched for it but could not find it anymore. The chart was listing main/pilot/clip at different temperature and elevation.

Does anyone still have that?

thanks

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how come that chart says the main jet STOCK is 178....my manual from 1999 says the main jet stock is 172.

i have a 172 & my bike is fouling on cold accelerations....i wonder if that could be the issue.

I have an 02 and my stock jet is 178. 👍

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How accurate is this chart? I have been working on my jetting on my 05 250 to eliminate my pipe from spooging. I ride in Oregon about 1000-2000ft elevation in temps from about 45 degrees on up in the spring & summer. Right now I have a 48p, 178m, N3EW-2nd and ride all over the throttle, some luggin and some WFO! I was gonna throw in a 45P to see if that would help eliminate the spooge, but this charts says a 45 is way off. everything else looks pretty acurate though.

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How accurate is this chart? I have been working on my jetting on my 05 250 to eliminate my pipe from spooging. I ride in Oregon about 1000-2000ft elevation in temps from about 45 degrees on up in the spring & summer. Right now I have a 48p, 178m, N3EW-2nd and ride all over the throttle, some luggin and some WFO! I was gonna throw in a 45P to see if that would help eliminate the spooge, but this charts says a 45 is way off. everything else looks pretty acurate though.

Yes, 45 is way off during the winter or anything below 60* IMO. I use a 50. Try a N3CJ needle in #2 or #3 position. I use a 172 MJ in the winter for trail work. Try a leaner slide. 8 or 9 even. RB design works grinds slides for cheap or you can buy different ones from JD for cheap too. Also, I bought some low flash point oil - Maxima SuperM injector oil or Amsoil Interceptor. Didn't try them though. They're just sitting on the shelf. 👍

If you can sneak a non spark arrestor silencer during the winter then your spooge problem will be gone too.

Don't lean the MJ or slide if you race MX.

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