yz250f dilemma- what could it be?

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schmanman

Mi. Trail Riders

Member

Jan 9, 2007

437

0

• Mar 20, 2010

• #1

I'm asking this question for a buddy of mine-

he took off the head, and adjusted the valves, and put everything back together. it runs like a champ, with the choke on, but when you turn the choke off it pops, misses, and backfires. It also doesn't idle, even with the choke on. you have to give it gas to stay running at low rpms.

he has cleaned the carb two or three times, and blown out all the jets. could the pilot circuit be clogged? how would you go about cleaning that?

thanks for all the help guys!

-Alex

 

robwbright

Member

Apr 8, 2005

2,283

0

• Mar 20, 2010

• #2

http://www.thumperfaq.com/jetting.htm

The pilot will cause EXACTLY what you are describing. I had the same problem last fall. There was a tiny piece of dirt I had missed.

 

J

_JOE_

~SPONSOR~

May 10, 2007

4,697

3

• Mar 21, 2010

• #3

Also double check the cam timing an valve clearance.

 

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schmanman

Mi. Trail Riders

Member

Jan 9, 2007

437

0

• Mar 21, 2010

• Thread starter
• #4

alright thanks, I'll let him know. :cool:
I told him to go clean out the pilot jet with a piece of wire or just to go buy a new jet.

 

IndyMX

Crash Test Dummy

~SPONSOR~

Jul 18, 2006

5,548

2

Amo, IN

• Mar 21, 2010

• #5

Don't clean jets with wire.. Use compressed air.

 

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sharky243

Member

Dec 14, 2008

246

0

• Mar 21, 2010

• #6

There is a removable plate on the carb slide, make sure it is not upside down. I made that same mistake and the bike did exactly what you are discribeing. After I put the plate back on properly, the bike ran perfect.

 

T

Tdoorn199

Mi. Trail Riders

Member

Jan 7, 2010

55

0

• Mar 21, 2010

• #7

yah definitaly dont use a peice of wire that could scar the jet