xr500 runnin rough

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Feb 2, 2007
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#1
g'day all,I'm havin a few little problems with my xr500.I can't seem to get my bike to idle properly i have changed the o'rings in the inlet manifold which seem to make it run a little smoother.I have also changed the valve clearances checked the cam timing which looks spot on and cleaned the carbs out a few times.When i give it a good rev it crackles and pops on the down stroke then it stalls and spits back out the carby and when i turned it off today it backfired out the exhuast.Besides this it runs and rides fine but won't idle properly or for more than a minute at the most.
 
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#3
Drew.

When you cleaned the carbs, did you remove the pilot jet and make sure you can see through the center of it? If not, you may want to do it again. Also, check the intake manifold for cracks. Over time, these harden and crack or seperate from the aluminum flange. The cracks are hard to see but, will make the bike hard to start.

Another little tip. Unscrew the sparkplug cap from the coil wire and take a screwdriver and unscrew the slotted brass insert where the spark plug goes. Under there you wil find a little spring and a resistor. Take the resistor and throw it as far as you can and replace it with a piece of copper rod the same length and diameter as the resistor. Those resistors go bad after time and will cause the bike to be very hard to start.

If after all of that the bike still pops back, you may need a valve job.

Good luck. :cool:
 
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#4
cheers i'll give it a go,the motor had a full rebuild 6 months before i bought it but it sat for a few months before i got it.
 
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#5
Drew.

You may want to recheck the valve clearances. Many times after a rebuild, the valves will seat in very quickly and lose their clearance. Spitting back through the carb is an indication of that.
 
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#6
Cleaned the carb again and there was realy fine dirt in the bowl,redone the valve clearances and put some gasket goo in between the inlet and motor.Runnon really good idles good but when i turn it off it backfires out the exhuast a couple of seconds after it stops runnin.
 
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#7
drew0790 said:
Runnon really good idles good but when i turn it off it backfires out the exhuast a couple of seconds after it stops runnin.
Drew.

Well, we're gaining on it. :cool:

That could be rich jetting or an air leak in the exhaust system. Cold air, introduced to a hot, fuel mixture laden pipe will cause a backfire. Check your head pipe copper o-rings and the seal between the head pipes and silencer for proper sealing.