Turned fuel off while idling - revs wide open?

threefiddyone
Profile picture for user threefiddyone
Posts
74
Joined
12/16/2014
Location
Baton Rouge, LA US
threefiddyone
2004 CR250.  The bikes been sitting for about 9 months with the same gas in it.  I cranked it today and it ran fine.  I wanted to get all the old gas out of it so I turned the fuel off at the petcock while it was idling to try and empty the carb.  As expected, it started to idle up as I assumed it was running out of gas, then it went wide open for about 15 seconds.  I tried to use the kill switch to kill it but for some reason that didnt work (thats a whole different problem).  So I turned the fuel back on at the petcock and that got it to stop and come back down to a normal idle.  It was then that the kill switch worked to kill it.  I am so confused.  Thats not normal right?  I repeated the process again and the same thing happened.

1.  Do you think that something with the old gas could have gummed something up in the carburetor causing it to rev wide open when I turned the fuel off?  It makes no sense to me.  It ran fine when I rode it and only did the wide open thing when I turned the fuel off.  Do you think I should tear down the carb and clean it?

2.  Why do you think my kill switch wouldnt work when it was wide open, but worked whenever it came back down to an idle?



Thanks in advance.  
|
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3639
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 8/14/2019 7:08am
8/14/2019 7:08am
When the bike runs very lean ( like running out of fuel) it will rev to the moon and the kill switch will do nothing to stop it. This is also very hard on the topend of the engine and it also reduces the oil it needs to survive.
Just remove the fuel line to the carb and drain the tank.
And yes, old fuel will clog up the pilot jet very quickly. Remove it and clean or replace.

Paw Paw
4
threefiddyone
Profile picture for user threefiddyone
Posts
74
Joined
12/16/2014
Location
Baton Rouge, LA US
threefiddyone 8/14/2019 7:19am
8/14/2019 7:19am
Paw Paw 271 wrote:
When the bike runs very lean ( like running out of fuel) it will rev to the moon and the kill switch will do nothing to...
When the bike runs very lean ( like running out of fuel) it will rev to the moon and the kill switch will do nothing to stop it. This is also very hard on the topend of the engine and it also reduces the oil it needs to survive.
Just remove the fuel line to the carb and drain the tank.
And yes, old fuel will clog up the pilot jet very quickly. Remove it and clean or replace.

Paw Paw
Thanks man. Do you think it could have damaged the motor from running wide open 10-15 seconds like that? It only has like 20 hours on the top end so I really hope not.
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3639
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 8/14/2019 12:10pm
8/14/2019 12:10pm
Pull the exhaust pipe and look at the piston skirt through the exhaust port. If it is scratched up it will need attention.

Paw Paw
1
Bennett59
Profile picture for user Bennett59
Posts
865
Joined
9/3/2015
Location
Bakersfield, CA US
Bennett59 8/15/2019 7:22am
8/15/2019 7:22am
threefiddyone wrote:
2004 CR250.  The bikes been sitting for about 9 months with the same gas in it.  I cranked it today and it ran fine.  I wanted...
2004 CR250.  The bikes been sitting for about 9 months with the same gas in it.  I cranked it today and it ran fine.  I wanted to get all the old gas out of it so I turned the fuel off at the petcock while it was idling to try and empty the carb.  As expected, it started to idle up as I assumed it was running out of gas, then it went wide open for about 15 seconds.  I tried to use the kill switch to kill it but for some reason that didnt work (thats a whole different problem).  So I turned the fuel back on at the petcock and that got it to stop and come back down to a normal idle.  It was then that the kill switch worked to kill it.  I am so confused.  Thats not normal right?  I repeated the process again and the same thing happened.

1.  Do you think that something with the old gas could have gummed something up in the carburetor causing it to rev wide open when I turned the fuel off?  It makes no sense to me.  It ran fine when I rode it and only did the wide open thing when I turned the fuel off.  Do you think I should tear down the carb and clean it?

2.  Why do you think my kill switch wouldnt work when it was wide open, but worked whenever it came back down to an idle?



Thanks in advance.  
Yea they rev like crazy when fuels off or running out of fuel I found out the hard way. 125 ran out of fuel when I was younger and it took off like crazy and hit a jump and into the face of another job broke my wrist. Make sure connections on kill switch are good I had a 06 Honda and Kill switch always kept coming apart

Post a reply to: Turned fuel off while idling - revs wide open?