Won't kick over, when jumped it starts but rev's out of control

Weber · 02-07-2008, 01:29 PM

I'm needing some advice, I own a 99 CR125R and it has been sitting for about 4 months. I flushed the gas and put a fresh mix in, changed the spark plug (I am getting a good spark) and had the carb cleaned. It still won't start, it appears to be soaking my plug when i kick it over. I've also jump started it, one time i thought i got lucky cause it started but then all of a sudden it started revving out of control and the kill switch wouldn't even kill it so i ended pulling the lead wire off. I've checked my throttle cable and there appears to be nothing wrong with its position. I'm baffled...

tigmaster · 02-07-2008, 01:49 PM

Excessive revving usually means a super lean mixture, or in most cases a limited fuel supply. If you have ever ran a 2 stroke bike out of fuel, it revs super high in its final moments. You say you changed the plug but have you actually checked the spark? I will get to that in a sec. However, how hard is it to kick over? Can you turn it over by hand? If so, then its time for a new top end. As far as checking the spark, it is fairly simple. Just remove the spark plug but the reattach it to the plug wire and hold it against a bare piece of metal while you kick the bike over and look for a spark between the electrode.

gscx · 02-07-2008, 01:50 PM

maybe your throttle slide is stuck a little open, or you have a vaccum leak, this happened to me one time, check your air box and boot for any holes, and then check the boot between the carb and the reed valves

tigmaster · 02-07-2008, 02:50 PM

Hopefully his filter is not that restrictive though. If his bike is jetted to run that different between a filter on and off he should buy a new filter. I was using the filter to explain the vacuum leak thing. Remember, no MAF sensor on bikes, the more air the get, the leaner they get so in theory you would be right. However air filters are so high flowing that a vacuum leak should not cause your bike to rev excessively. However, you said it happened to you. Can you explain what happened and what your bike did? The throttle slide definitely is something that needs to be looked into as well if he hasn't already.

gscx · 02-07-2008, 07:20 PM

well it really only affects you if the leak is on the boot that is closest to the engine because the air and fuel is already mixed and then its getting a shitload more air, and the hard starting is a sign because the engine wont be able to create enough suction to draw the mixture in because of the rip, or hole, so that is why he had to pull start it because the piston moves faster for longer and this will give you enough suction to start the cycle. but it will idle like you are giving it throttle but you are giving it none, and it acts like it runs super lean

gscx · 02-07-2008, 07:22 PM

and plus it has been sitting for awhile so it probly dry rotted

wr250f95 · 02-07-2008, 08:43 PM

perhaps an airleak?

tigmaster · 02-07-2008, 10:23 PM

Well, gscx's description would make me question an air leak too.

02-07-2008, 01:29 PM	#1 (permalink)
Weber C Rider Join Date: Feb 2008 Posts: 1 iTrader: (0)	Won't kick over, when jumped it starts but rev's out of control I'm needing some advice, I own a 99 CR125R and it has been sitting for about 4 months. I flushed the gas and put a fresh mix in, changed the spark plug (I am getting a good spark) and had the carb cleaned. It still won't start, it appears to be soaking my plug when i kick it over. I've also jump started it, one time i thought i got lucky cause it started but then all of a sudden it started revving out of control and the kill switch wouldn't even kill it so i ended pulling the lead wire off. I've checked my throttle cable and there appears to be nothing wrong with its position. I'm baffled...

02-07-2008, 01:49 PM	#2 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,526 iTrader: (1)	Excessive revving usually means a super lean mixture, or in most cases a limited fuel supply. If you have ever ran a 2 stroke bike out of fuel, it revs super high in its final moments. You say you changed the plug but have you actually checked the spark? I will get to that in a sec. However, how hard is it to kick over? Can you turn it over by hand? If so, then its time for a new top end. As far as checking the spark, it is fairly simple. Just remove the spark plug but the reattach it to the plug wire and hold it against a bare piece of metal while you kick the bike over and look for a spark between the electrode. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

02-07-2008, 01:50 PM	#3 (permalink)
gscx Pro Mototips Member Join Date: Aug 2007 Location: bridgeville DE Posts: 2,233 iTrader: (0)	maybe your throttle slide is stuck a little open, or you have a vaccum leak, this happened to me one time, check your air box and boot for any holes, and then check the boot between the carb and the reed valves __________________ Sold

02-07-2008, 02:50 PM	#4 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,526 iTrader: (1)	Hopefully his filter is not that restrictive though. If his bike is jetted to run that different between a filter on and off he should buy a new filter. I was using the filter to explain the vacuum leak thing. Remember, no MAF sensor on bikes, the more air the get, the leaner they get so in theory you would be right. However air filters are so high flowing that a vacuum leak should not cause your bike to rev excessively. However, you said it happened to you. Can you explain what happened and what your bike did? The throttle slide definitely is something that needs to be looked into as well if he hasn't already. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

02-07-2008, 07:20 PM	#5 (permalink)
gscx Pro Mototips Member Join Date: Aug 2007 Location: bridgeville DE Posts: 2,233 iTrader: (0)	well it really only affects you if the leak is on the boot that is closest to the engine because the air and fuel is already mixed and then its getting a shitload more air, and the hard starting is a sign because the engine wont be able to create enough suction to draw the mixture in because of the rip, or hole, so that is why he had to pull start it because the piston moves faster for longer and this will give you enough suction to start the cycle. but it will idle like you are giving it throttle but you are giving it none, and it acts like it runs super lean __________________ Sold

02-07-2008, 07:22 PM	#6 (permalink)
gscx Pro Mototips Member Join Date: Aug 2007 Location: bridgeville DE Posts: 2,233 iTrader: (0)	and plus it has been sitting for awhile so it probly dry rotted __________________ Sold

02-07-2008, 08:43 PM	#7 (permalink)
wr250f95 Super Moderator Join Date: May 2007 Location: New Mexico Posts: 7,831 iTrader: (1)	perhaps an airleak? __________________ "LIFE'S JOURNEY IS NOT TO ARRIVE AT THE GRAVE SAFELY IN A WELL PRESERVED BODY, BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT, SHOUTING'...HOLY S**T... WHAT A RIDE!" this, is why I ride.

02-07-2008, 10:23 PM	#8 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,526 iTrader: (1)	Well, gscx's description would make me question an air leak too. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

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