2009 kx250f dropped a valve?

kawimoto_615
Profile picture for user kawimoto_615
Posts
60
Joined
10/18/2011
Location
Roseville, CA, USA
kawimoto_615
Edited Date/Time 9/15/2012 10:59pm
So I was out riding yesterday on my 250f that has literally less than 5 hours and everything has been great till yesterday. So I was coming into a corner and the bike just stalls and has no compression afterwards. No bangs no weird noises. I just rebuilt everything in the top end. Literally every part... So I took it home and tore it down and it dropped the left side exhaust valve?!? I don't even know how cause I'm not a super fast rider so I don't float them. It barely nicked the piston so I should be fine there. I just installed a Tokyo mods cam chain tensioner the other day but it ran fine with that in there on Saturday.
|
kawimoto_615
Profile picture for user kawimoto_615
Posts
60
Joined
10/18/2011
Location
Roseville, CA, USA
kawimoto_615 9/4/2012 11:06am
9/4/2012 11:06am
Of course I'm gonna need a new valve, but do I need to get the seat cut again? All the others are good (checked them) what else should I replace. Oh and the keepers were still sitting inside the retainer it's just like they failed and the valve fell out.
DTHA70
Profile picture for user DTHA70
Posts
336
Joined
9/25/2008
Location
Surprise, AZ, USA
DTHA70 9/10/2012 10:50pm
9/10/2012 10:50pm
new valve, cut seat, new locks to match to new valve and might want to do a top spring retainer.
privateerconnection 9/11/2012 6:21am
9/11/2012 6:21am
and I would put a crank in it. all that energy was transferred down the connecting rod and into the lower rod bearing so its just a matter of time before the crank goes out or even worse breaks and wipes out your cases. A complete rebuild is in order bottom to top. Just my suggestion.
RACESTHILAIRE 9/11/2012 6:33am
9/11/2012 6:33am
Make sure you or someone familiar with inspecting valve guides and seats closely checks over your head. Sounds like you made an error while assembling your head or setting your cam chain tensioner. Cutting that one valve seat again could have an affect on performance and depending on how much was taken before, you might not have the ability to adjust valve clearance if cut again because shim size will be too small.

Be very cautious, mistakes can mean more than just $$$ they can also lead to injury depending on when the engine fails again.

The Shop

See All »
kawimoto_615
Profile picture for user kawimoto_615
Posts
60
Joined
10/18/2011
Location
Roseville, CA, USA
kawimoto_615 9/15/2012 10:59pm
9/15/2012 10:59pm
RACESTHILAIRE wrote:
Make sure you or someone familiar with inspecting valve guides and seats closely checks over your head. Sounds like you made an error while assembling your...
Make sure you or someone familiar with inspecting valve guides and seats closely checks over your head. Sounds like you made an error while assembling your head or setting your cam chain tensioner. Cutting that one valve seat again could have an affect on performance and depending on how much was taken before, you might not have the ability to adjust valve clearance if cut again because shim size will be too small.

Be very cautious, mistakes can mean more than just $$$ they can also lead to injury depending on when the engine fails again.
why would i need to replace the crank if the bike has barely over 60 hours on it? and ive been good at changing my oil and keeping the whole bike maintained. the valve literally barely touched the piston, i didnt even hear it thats how little they hit....

i though i could have installed it wrong too but its ran fine before and i would think that if i installed it wrong it wouldve dropped in the first place. the seats were shaved for more performance so its prolly out of reach for them to be cut again im guessing but then again like i said i only have like 4 hours total on the new top end. and only like 2 hours of real riding... (the first two i took it pretty easy)

now onto the cam chain tensioner, it didnt skip time. i know that becasue everything was were its supposed to be when i pulled the valve cover. the chain was still tight too. i called pro circuit just so i could talk to someone who knows what they are doing and they said that it really just sounds like i was unlucky and my keepers failed on one, it does have the tokyo mods tensioner in there so its not like the automatic one failed like ive heard of in the past....

Post a reply to: 2009 kx250f dropped a valve?