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What float height are you 250 guys using?

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Trying to determine some jetting changes possible vacuum leak, lean surge, hanging idle, horrible fuel mileage on my 2008 yz 250. I checked float height it was 4.15mm. I set it to about 6.9mm ...manual calls for 5.5-7.5mm.

I fired the bike up this AM and it was idling better more steady but if i went to tip the bike slightly the bike would begin to stall???? This makes me think my fuel level in the bowl is too low now.

For those of you that have set and reset your float level what # did you finally decide on? hoping to only need to pull carb completely one more time and get it straight this time around.

Thanks

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Remember when you're measuring the float you need to tip the carb at a 45 degree angle or you will get inaccurate/differing results as the float may actually be pushing down on the plunger instead of resting on it.

I think I settled around 6.5. I think it took me 3 or 4 tries to get it right.

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Right I understand the principle of setting float height just looking for some real world feedback from those guys who have done the trial and error to find what the sweet spot is much like I am beginning to do.

Killaz thanks. I was actually thinking of setting around there this time around.

thanks

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This is the way i set my float height. There should be a line on the float that you have to get parallel to the carb body. Just make sure that you keep the needle valve seated while doing this otherwise things will go out of wack.

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Remember when you're measuring the float you need to tip the carb at a 45 degree angle or you will get inaccurate/differing results as the float may actually be pushing down on the plunger instead of resting on it.

I think I settled around 6.5. I think it took me 3 or 4 tries to get it right.

killaz is correct, watch that plunger or you'll f with it all day:banghead:

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Well I set it around 6.5mm the bike seems to run fine but still smokey. I am racing the thing on Sunday and it should work fine. I tore the carb apart and cleaned everything. Jd jetting yamalube 32:1 needle 2nd clip from top. Bike runs well lean surges sporadically in the past, haven't ridden it since float adjust though. It seems like a vacuum leak at times. Oh well I will replace left and right crank seals next. Trying to adjust the float tang in a .5 mm increment was silly.👍

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i just rebuilt my 05. when i was going threw the carb i got my book out and set the float as to what the book said. well didn't work. went to jump a double and the bike quit right on the face. didnt crash. so i pushed the bike back to the truck and tore the carb apart. when i poped the bowl off it was empty. i set the float so it was pointing down a little bit. not even with the bowl surface. ( carb upside down ). put it back on turned the fuel on and no leaks. layed the bike over and fuel did not come out until the handle bar was almost on the ground. now it starts and idles the way it should. oh yeah cleared the double this time. all the parts were new. hope this helps.

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Remember when you're measuring the float you need to tip the carb at a 45 degree angle or you will get inaccurate/differing results as the float may actually be pushing down on the plunger instead of resting on it.

I think I settled around 6.5. I think it took me 3 or 4 tries to get it right.

Even with the carb at a 45 degree angle the little plunger still compresses. I have to keep it almost vertical to keep the weight of the floats from compressing the plunger.

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i had your same problem. lean surge on idle, but i was fouling plugs down low on cold accelerations.

top end it always screamed like a champ.

i replaced both crank seals, set float height to perfectly parallel to the line, tried diff pilot jet sizes, screwed with air/fel screw til i was blue in the face, checked reeds, checked for vacuum leak....nothin.

at the end of the day, i switched to a *hotter* plug (BR8es-stock), went to *stock* jetting (50/178), and she runs like a champ now

plug is a little white, but dry as anything...and the bike is staying nice & cool.

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i had your same problem. lean surge on idle, but i was fouling plugs down low on cold accelerations.

top end it always screamed like a champ.

i replaced both crank seals, set float height to perfectly parallel to the line, tried diff pilot jet sizes, screwed with air/fel screw til i was blue in the face, checked reeds, checked for vacuum leak....nothin.

at the end of the day, i switched to a *hotter* plug (BR8es-stock), went to *stock* jetting (50/178), and she runs like a champ now

plug is a little white, but dry as anything...and the bike is staying nice & cool.

So you installed a BR8ES or something hotter like a 9 series?

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i had your same problem. lean surge on idle, but i was fouling plugs down low on cold accelerations.

top end it always screamed like a champ.

i replaced both crank seals, set float height to perfectly parallel to the line, tried diff pilot jet sizes, screwed with air/fel screw til i was blue in the face, checked reeds, checked for vacuum leak....nothin.

at the end of the day, i switched to a *hotter* plug (BR8es-stock), went to *stock* jetting (50/178), and she runs like a champ now

plug is a little white, but dry as anything...and the bike is staying nice & cool.

What jetting were you running before?

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