Intake valves? Need diagnosis - video/audio provided

[hotshot38]

...in more ways than one.



http://www.gz250bike.com/forum/pictu...&pictureid=278

I don't think this intake valve spring is supposed to be hitting this cover



http://www.gz250bike.com/forum/pictu...&pictureid=279

[spldart]

Doh!!!

The more I look at this the more I wonder how the spring retaining hardware struck the top of the head like
that.
Did the valve shaft break?
Spring retainer fail? Keepers fail?

Were you turning insane rpm? This looks like a valve float kinda failure...

Oh... And you may not be to hosed.
Remove your engine head.
Examine piston top. Don't remove cylinder.
Is piston damaged around where that valve was position?
Not just a spot where the carbon got knocked off but is it cracked or chipped or broken.
If yes then maybe motor is impractical repair.
If no then.
Get donor engine head. Steal a valve, spring and retaining hardware. Slip the donor valve in old head and
using lapping tool and some compound for a bit.... Assuming the valve fits in guide properly. Lap the crap
out of it.... Look up this on youtube... Then install donor hardware and remount head as per service manual
with new gasket...

Possible joy for cheap.
I've done it. Cracked valved on old motor. Fixed for about 50 bux and it ran a good while.

[hotshot38]

Yeah...the spring is definitely out of place. I can compress it slightly with my finger. AND, the clicking sound does not correspond with the spring/retainer hitting the wall.

Now, as for the cause of all this....that is going to be for a day when I have more energy. Gonna consult with some local motorcycle buddies and maybe they'll volunteer to fix it. *fingers crossed*

[spldart]

Originally Posted by hotshot38

AND, the clicking sound does not correspond with the spring/retainer hitting the wall.

Ok... That definitely sounds like piston head and valve are smacking around a bit.

[WJTED1]

I thought I lost my video of the breakdown but I have it. Do I have to post through YouTube?

[hotshot38]

I posted to youtube and just posted the link here. Not sure if you can post/upload videos to this old vB forums

[hotshot38]

This thread may give more insight
Dropping Valves
http://www.gz250bike.com/forum/showthread.php?t=6215

I'm going to try to get the head off tonight

[hotshot38]

When I took the cover off the spring basically could be pulled off by hand. The 'keepers' looked damaged...at least one half moon did. Sorry, no picture.
The valve itself is definitely lower than the other valves and will not budge using hand pressure.
Clicking noise is still there when I turn it over so I suspect it is kissing the piston.

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6. Exhaust valves

[spldart]

:sad face:
It looks like the stem of the valve is intact and your keepers got out due to valve float from
over revving.
Considering how low that 'stem' is in the photo there is no doubt the valve has contacted
the piston.
I'm anxious to see what the piston and the rest of that valve look like.
Thanks for the pictures.

[hotshot38]

Here is the piston:



And here is the valves



And here is the extracted valve which I bent with my mind, Kreskin style



I think I am thru with GZ250's. This will soon be on Craigslist as a basketcase.