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Offline 2005yz250

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Is this too lean?
« on: April 02, 2012, 10:27:16 PM »
Hello once again I have to tune my bike to get better and better response ( go figure).  Right now i run a 178 main with a 50 pilot, air screw 1 turn out with a stock pipe and pro circuit long silencer.  My elevation is 550 ft and the average humidity is 80%.  My question is, would going to a 175 main and a 48 pilot be too lean?  I put them in and can definitely feel the difference in throttle response around the yard, but im afraid when I am out pinning it on the track the bike will be too lean? Is this true or am I just being too cautious? I just want some more response without burning up the bike.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline SachsGS

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Is this too lean?
« Reply #1 on: April 03, 2012, 12:50:16 AM »
Post pictures of your sparkplug with the various jetting specs.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline 2005yz250

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Is this too lean?
« Reply #2 on: April 03, 2012, 01:02:31 AM »
Will do when I get the chance.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline eprovenzano

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Is this too lean?
« Reply #3 on: April 03, 2012, 01:01:43 PM »
what's the reason for the change?  Does your bike bog, or is unresponsive somewhere in the RPM range?  Is the plug black, tan or white.  These are the things to consider when making jetting changes.  Post a pic of the plug as that will help us answer the question.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
Eric Provenzano
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Offline metal_miracle

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Is this too lean?
« Reply #4 on: April 03, 2012, 05:46:59 PM »
often you can feel the bike dies on wide open throttle

if its to lean on the main jet
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline 2005yz250

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Is this too lean?
« Reply #5 on: April 03, 2012, 11:54:19 PM »
I find it to be just a little too sloppy from like 1/8 to 1/4 throttle.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline metal_miracle

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Is this too lean?
« Reply #6 on: April 04, 2012, 12:04:26 AM »
think i would have hold throttle

just above idle and adjust the air screw out until it raises in rpm  then back just a bit

sine you air screw seem far in
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline LukeDuke25

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Is this too lean?
« Reply #7 on: April 10, 2012, 01:37:15 PM »
Do a plug chop test, that is the true measure of your jetting.  If you ride it around the yard for a bit, and it stutters on top then clears out, your main is too rich.  If you feel poor response down low or at  1/8 to 1/4 throttle - your pilot circuit is rich.  Your plug should have a nice coco/tan color on it after the chop test.

« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline MyckMcClung

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Is this too lean?
« Reply #8 on: April 10, 2012, 04:25:38 PM »
post pics
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
If a pair of 2" brass balls isn't working, I doubt that the 3" model will make much difference.

Offline arnego2

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Is this too lean?
« Reply #9 on: May 16, 2012, 02:26:53 PM »
Change one thing at the time, start with float height and go from pilot > needle > to main.

I run 45 pilot with a JD needle, on stock I'd run 48 height and average humidity comes close to mine too.
Stock needle 3 rd position, JD needle (red) 4rth position.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »