2003 WR250 F - eng. won't idle down and carb starts to overflow
When the bike really warms up running dirt roads, the engine starts to rev higher and won't idle down on its own - eventually, the carb starts to overflow. After shutting down for a while, the carb overflows when I just turn the petcock on. Carb's been cleaned, needle replaced, rubber diaphram (?) replaced, etc. Still a problem.
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Re: 2003 WR250 F - eng. won't idle down and carb starts...
Have you checked the float level in the float chamber?
I guess you may have to reset the float pin adjustment, its allowing more gas to pass through thn required and thus the overflow!
Not bad too, when you are working on the float assembly take the opportunity to blow out the fuel line from petcock to the carburator via the seat for the float pin,any foreign particals there would stop the float pin to seal up and thus overflow.
Fit in an inline fuel filter , this will help keep out the dirt or whatever.
Hope this helps.
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Urals need to be throughly warmed up before riding, old technology engine. As far as the revving, I'd Check for vacuum leaks at the
Carburator with some carb cleaner while idling, and if that's not it, I'd check the choke.
You have a vacuum leak on the intake.Start the engine and spray carb cleaner around all of the vacuum hoses and see where the engine REVS UP while you are spraying there... that is your leak area... correct it.
The two carbs are not balanced to each other. Balance as follows; Start the bike then increase the idle on the left carb to a high idle. Now unplug the right cylinder and the engine will slow down some. Now slowly turn the idle down on the left carb until the engine just dies. Hook up the right plug wire then do the same proceedure for the right carb. Now both carbs are balanced. Hook up the left wire and start the engine again. The bike will be running faster than you want so now adjust the idle screws on both carbs equally to get the desired idle speed. Please rate my answer. Thanks.
Sounds like the carbs were not properly cleaned or set up. Choke should cause the cold start rpms to be higher than what you are experiencing. Application of choke to a warmed up engine will usually cause the engine to stall.
2 things need to be done first start your bike get a can of wd40 after your bike is warm and running spray around the carb jointsall 4 of them if your engine changes rpms up or down you have a intake leak ether your carb joint gaskets or o-rings need replacing or your carb joints are old and need replacing. at this point wont hurt to have you carbs cleaned also
You need to fix the fueling first - without fuel it won't run!
Your other problem sounds like an air leak - either the manifold or the carb. Check by spraying WD-40 or CRC at the manifold and carb join while the bike is running - if the revs change (either up or down) you have a leak.
My 'wing won't run unless it has been warmed up some. I would suggest that you r&r your carbs to make sure the jets in the bottom are working correctly. They tend to get plugged up, especially after sitting & the aluminum flaking off inside... Rick
Running well at high revs would indicate that all the fuel and air it needs are getting to the engine and you also have a good spark. Probably no problem with air and fuel filter ( if fitted) or sparkplugs.
Running hot, and bad idling are signs of a lean air fuel mixture. The engine is probably not getting enough fuel at low revs.
This could be caused by an air leak between the carburettors and the engine. Check that the vacuum line to the fuel tap is properly secured at both ends. It is behind the fuel line at the tap.
Get a a short length of hollow plastic tube and use it like a stethascope - put one end to your ear and move the other end around your carburettor mounts with your engine revs as low as you can get, and listen for any sucking noises that would indicate a leak. Look for cracks in the rubber inlets.
The other possibility is that there is an internal blockage in the idling jets or idling fuel circuit. This is where dirt tends to lodge because the jet dimensions and passageways are very fine - The high speed jets are much bigger and dirt often just passes straight through.
Try a little bit of choke while the engine is warm to see if you get a stronger low speed response. If so that would point to an internal blockage.
You will open those things up, and they will probably look pretty clean, but the problem with your carbs is in the Idle circuit - too small for you to see into.
If you do a search of carb cleaning or related topics, you'll see that alot of folks with cab problems try to clean their carbs ... only to have to open them up again due to improper cleaning (They are difficult to clean properly, require alot of patience) So, I would suggest that you have them cleaned professionally, or at least buy good carb dip to get them really clean. Spray cans of carb cleaner are worthless. Might as well wash em with dish soap.