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how long can a set of stock valves go??

I really dont want to have to put new vales in my bike:banghead:

is power lost when valves are worn or just reliability?

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stock is the best way to keep it reliable

i change mine about every 60hrs but it depends on how the bike was rode

ps dont buy the cheep ones like the faction mx .... lasted about 5 hrs

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Everybody has different times of changing valves. For me around 50-60

But when the bike gets hard to start, thats when you should check your valves. If the bike is losing power, you most likely need a new piston.

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My son had 130 hours of hard racing on his stock valves and they were still looking good. The seats looked great also.

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Check your clearances. If in spec, perform a leakdown test and if in spec, no need to replace. If you have shimmed your valves more than once, check the valve for stretch. If yout of spec, replace valve...

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ive never shimmed just been checked when i had the piston and clutch put in and they were good then

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My son's kx250f valves never went out of spec the first 130 hours he ran it. I overhauled the top end and he has about 30 hours on it since and still in spec. Kawasaki's just don't go out of spec very often. I can honestly say I don't know a single person that has had an 06-08 go out. I'm sure there have been but I don't know anybody personally. Now the 04-05, that's another story.

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when you overhauled the topend you put valves in too?

I put in a new piston and rings, valves, springs and collets. Had the valve seats reground.

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It's good to hear the life that the KXF's are getting.:lol:

How long do valves last? Hmmm? Thats a tough question.Guess it could depend on the size of your wallet or your conscious and how long you want to push things.Valves are good until they close up once.Piston life can determine when you change your valves too since your all ready in there.

How long does a piston last? Well they lose power shortly after their run, 5-10 hrs.Enough to notice? Not for me.50 - 60 hrs for most guy's who race is about right.100 hrs I start to wonder about cracking but hell if it ain't burning oil why fix it.This is where your conscious comes in to play and you start thinking about catastrophic failure.If you last 100+ hrs and go in for a piston you should do the valves and cam chain for insurance.

So we don't race but run the snot out of our bikes in the desert and sand dunes.Not a easy life and a dusty one.I redid the entire top end on the 250 last year(April 08) at 116 hrs With no valve movement or blow by.My conscious got to me.When the bike came apart it still had plenty of life left in them parts. At 191 hrs today, 75 hrs later it's running like a top.How long do we run this time? 130-140-150hrs ? Till something gives Or a valve moves? I start feeling uneasy at 100+. 54hrs on the KXF 450 since April 08.Man time flies when your having fun.That's 4 solid weeks in the desert this year and some day trips.:worthy:

http://www.thumpertalk.com/forum/showthread.php?t=623036&highlight=116+hours

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Great thread, Ive been wondering the same thing. I too have had that un-easy feeling since 100hrs...at 110 now...no valve movement yet....we'll see...

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stock is the best way to keep it reliable

i change mine about every 60hrs but it depends on how the bike was rode

ps dont buy the cheep ones like the faction mx .... lasted about 5 hrs

i put faction stainless steel valves and springs in my old crf, they lasted forever never had 2 shim them. i rate them highly

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I just did top end then on my 09 at 45hrs, all new valves, piston, rings and seats re-cut. All comes down to how you ride the thing i guess. .

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when i bought my bike the mechanic was friends with the previous owner and said he did a valve job and everything was in spec. supposedly stock are the best valves im just worried because i really dont know how to check them and idk if i wanna tear the engine apart but on the other hand i dont want anyhing bad to happen. My dad and myself plan on doing a complete top end next year with a hi comp piston and possibly valves.

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we just did a 09 250F 36hrs valves ect and replace the ring aswell piston still good.

customers words valves need doing getting hard to start.

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we just did a 09 250F 36hrs valves ect and replace the ring aswell piston still good.

customers words valves need doing getting hard to start.

He probably meant valves need shimming.

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