gpx250 sparkplug problems
Fri Jan 12, 2007 1:26 pm
Hi,
I have a second hand 99 model gpx250. Riding down the freeway one night loud pop, loss of power. Upon closer inspection one of the spark plugs had popped right out and now is unable to screw back in so I am thinking it has been crossthreaded. Can I fix this or do I need a new head?
Many thanks for your help
I have a second hand 99 model gpx250. Riding down the freeway one night loud pop, loss of power. Upon closer inspection one of the spark plugs had popped right out and now is unable to screw back in so I am thinking it has been crossthreaded. Can I fix this or do I need a new head?
Many thanks for your help
Fri Jan 12, 2007 5:58 pm
Look at the thread on your sparkplug, is it all torn up? any visible damage?
do the same with the internal thread on the head, if its damaged, filings and chewed threads may have fallen into the barrel. So your gonna have to take the head off anyway and inspect the cylinder for damage, scratch that, PRAY there is no damage. If you were lucky and the sparkplug was just real loose and worked its way out, the threads all seem undamaged, it may just be a case of crud in the threads where the sparkplug was working its way up and some of the thread (the deepest parts) would have been exposed to the combustion gases etc. This would have coated them in crud, which will need to be cleaned out (recommend taking the head off and doing it properly). I'd be buying a new plug regardless, and make sure u dont overtighten it when u get it back in, hand tight, then a quarter of a turn using a spanner/socket is a general rule which i follow, although if you have an accurate torque wrench, use that.
A point to note that if the plug was working its way out, the end threads may be damaged whilst the majority of the deeper thread is fine, the threads might have sheared at the top only, when there wasnt enough metal to contain the pressure in the cylinder. I hope thats clear, in any case, determine for sure if there is damage to the threads, if your unsure, take a pic and post it here.
Best of luck.
do the same with the internal thread on the head, if its damaged, filings and chewed threads may have fallen into the barrel. So your gonna have to take the head off anyway and inspect the cylinder for damage, scratch that, PRAY there is no damage. If you were lucky and the sparkplug was just real loose and worked its way out, the threads all seem undamaged, it may just be a case of crud in the threads where the sparkplug was working its way up and some of the thread (the deepest parts) would have been exposed to the combustion gases etc. This would have coated them in crud, which will need to be cleaned out (recommend taking the head off and doing it properly). I'd be buying a new plug regardless, and make sure u dont overtighten it when u get it back in, hand tight, then a quarter of a turn using a spanner/socket is a general rule which i follow, although if you have an accurate torque wrench, use that.
A point to note that if the plug was working its way out, the end threads may be damaged whilst the majority of the deeper thread is fine, the threads might have sheared at the top only, when there wasnt enough metal to contain the pressure in the cylinder. I hope thats clear, in any case, determine for sure if there is damage to the threads, if your unsure, take a pic and post it here.
Best of luck.
Re: gpx250 sparkplug problems
Fri Jan 12, 2007 6:21 pm
deadpool wrote:.... Can I fix this or do I need a new head?....
This is easy to fix. You can use a Helicoil insert, (or the Pommie equivalent, I think its called a Timesert or something ? )
It will replace the thread that has stripped out in your head, and then you can screw in a new plug and be on your way. You should take the head off to do this, as you need to drill out the old plug-hole to clean up the old thread for the Heli-coil to be inserted properly. Its a minor pain in the arse, but its really only a couple of gaskets and a couple of hours............
Knock yourself out mate !!
Fri Jan 12, 2007 6:30 pm
Awesome,
thanks for the input guys. wont get a chance to work on it til tuesday but I will let you know how I go.
thanks for the input guys. wont get a chance to work on it til tuesday but I will let you know how I go.