Traildale1

Member
Apr 22, 2000
34
0
My 250F has just developed a severe idle speed problem. It will go from a normal idle speed to a 3000 to 3500 rpm (my guess) idle all by itself. If I drag the clutch and then pull it in again, it will drop back to a normal idle speed for a 4 or 5 seconds, and then pick up a few thousand rpm over the next couple seconds, like its got a mind of its own. Turning the idle speed down just makes the "normal" idle speed slower, or makes the engine stall very easily.
I just got the bike a month ago - used, but it was in storage since new and had zero hours on it. After the break-in period, it started and ran great and its got about 6 hours on it now. It's run great - no problems until now. Two rides ago, it developed an idling problem that has me baffled. It became hard to start and won't tolerate ANY choke until I get it running without choking it (get it turning over - barely - and then quickly reach down and blip the choke repeatedly to keep it running till its warm. Then the idle is either VERY slow and it stalls out, or VERY fast - don't know why.
Maybe an air leak has developed, causing the erratic idle? Where should I check? Any of you had this happen, and know what the real problem might be?:(
Thanks
 

DC3PIC

Member
Jul 4, 2001
31
0
How does it idle cold with the choke off? Have you checked the idle mixture? Sounds like it may be running rich. Just a guess.
 

yz250-effer

Member
Nov 4, 2000
305
0
Just a couple of maybe's ?

Make sure and check the intake rubber manifold boot for proper fit and that the clamp is tight. My clamp was not even on correctly when I inspected mine from the dealer. Also, make sure the air screw is set at stock ( 1 3/4 turns out ). If it is way off , it resembles an air leak.

That is all I can think of. Good luck in finding the problem.;)
 
B

biglou

As mentioned in the post above, keep an eye on the pilot screw. Okie had his work its way completely out (vibration?). I've read of a couple others that had the same thing happen to them as well.
 

yota

Member
Oct 9, 2001
293
0
Have you had the slide out of the carb? A lot of guys put the plate back on the slide upside down and this causes the same thing to happen but the bike will still run. The "pointed" end of the plate goes the opposite way from the "pointed" end of the slide.
 

Traildale1

Member
Apr 22, 2000
34
0
Found the problem! Woo Hoo! Back in business.
It was a partially plugged pilot jet/circuit. One of the local dealers told me that this was the first place to look if I'd let the bike sit more than a week between rides. Pulled the carb - carb cleaner - back together - runs great.

The dealer said that they've had a record number of plugged up carbs this summer and is blaming it on changes in the gas formulation locally (Minneapolis, MN). No evidence other than his guess at cause and effect. He advised completely draining the carb and tank if the bike is expected to sit more than a week if the bike has a plastic tank.

Guess I'll be more careful from now on.
Dale :cool:
 

Boozer

Member
Oct 5, 2001
351
0
the problem you had is know as 'hanging up'. This condition is caused by a lean pilot circiut, either by a lean pilot jet, or the circuit is partially obstructed, as you know.
 
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