yz250f 2007 valve problems.

M

maticvidmar

Hello and thanks for help advance.
I bought a used yz250f 2007 and it was hard to start. So I check a valve clearance and they were way to small. Even the marks on camshaft wasn't right. So I buy new timing chain and the marks is now OK. But valves still have no place and they're open all time so bike have no compression. I'll adjust the valves but I hear that's dangerous because valves on this models are getting bigger and they can bi adjust 1-2 times but then they can break.
I read a couple formus about valves on 2007 and I'll be very grateful if somebody have any experience what happen after setting valves or has anyone got problems with broken valve after that.

Thanks for all the answers
 
O

ossagp

You can reshim them several times from what I have seen. Is it all if the valves or are the intakes worse than the exhaust valves?
 
P

PawPaw

You can get away with doing a reshim on the valves a time or two, but the valves are getting longer and or the valve seats are being beat down and thus changing the valve clearances. You don't want to let one of the valves break as that is major engine failure and can create a complete engine replacement need.
You may want to think about having the head serviced and new valves , springs, guides, retainers and keepers installed. That way you will know it's condition.
Now also keep in mind that if the maintenance was neglected on the valves, most likely more involved maintenance issues like the crank were also neglected.
I know you just want to ride, but it's winter and the time is right for a complete tear down and rebuild so you can have a good ride in the spring and summer.

Paw Paw
 
O

ossagp

maticvidmar:
yes, the intakes are worse
Click to expand...

Bears out what Paw says, in my experience. Anymore I think I would rather see an engine that has the exhaust valves going out sooner than the intakes. That usually indicates that it was run too lean. Paw is likely dead on about the maintenance as a whole. Sounds line a great place to start a "build".
 
O

ossagp

I have the hardest time putting a head back together without putting new valves and guides in and having the seats redone. If the budget won't stand for the seats and guides, I guess I would just do the intakes.
 
P

PawPaw

Face it, the bike is 7-8 years old and shows signs of neglect. Thus it is time for a tear down, inspect and fix before it self destructs and cost more to fix the the bike would be worth. I know it's hard to see that when all that is desired is to ride, but this is the truth and needs to be done correctly or find another bike to put the money in to.
I suggest you will find more that just the intake valves are in need of attention. It most likely will need new valve guides, seals, retainers , keepers, seats cut or replaced and this is just the head. Now with the age of the bike I would further suggest it will need a crank, gaskets and seals for the balance of the engine.
I am not down on you or your bike, but a neglected bike will need a lot of tlc or you will spend most of your time broke down and will spend much more money due to constant failures if not addressed now.

Paw Paw
 
SRAD97750

SRAD97750

Moderator
Staff member
Lets not get too crazy.
I would at minimum tear the head off and check it out.
Inspect some things per the service manual and go from there.

No need to bid worst case scenario.
Set the valves and make sure they pass the water test. -BIG DAN:thumb:
 
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