Both INTAKE valves are stuck opened

[paan009]

Both IN. valves are stuck opened in the #2 cylinder.
No contact with the piston, but this definitely explains
why I couldn't get the motor to fire this past summer.
Any ideas and/or suggestions? Since I'm parting the motor,
I just want to know how I can sell the head in this condition.
Is it junk or just a valve keeper gone bad?

[Matchlessmingler]

My 2 cents but if the valves are stuck in open position it most probably is bent. They look tweaked at the valve head. This is likely to be a result of piston contact or perhaps dropped valves. Either way, it would require replacing the valves and valve guides. Hopefully someone with more experience will chime in and give you some options.

[paan009]

Thanks for the reply: I carefully inspected the #2 piston and didn't see
any marks on it. Never had both valve do this, but I did float 1 valve and it
took out the piston and valve head on an over-rev when I missed a shift!

[shnormo]

Valves are most likely bent. only way to really check is to pull the valve keepers out

[LiveFastDieLast]

As said above you will need to remove the vales for inspection.
If they are not visibly bent by eye or with a machinist square you will need some tools like this.

A indexing collet punch grinder


and a Height Guage with Dial Indicator attachment


A extremely flat surface will also be needed, A granite inspection table is the best but something level and flat should work.

The Valve will go in the Indexing Holder. Set the height gauge on the valve. and rotate the holder. This will give you a read out on the indicator and you can see if the valve is bent. You will see the dial indicator read from a positive to a negative number back and so on.
Or you will see very little movement on the gauge.
I have no idea what type of tolerance Yamaha has on the Valves but almost all dial indicators read out to .ooo1 of an inch

If you have any Tool and Die or machinist friends that will be the quickest way to get access to those tools.

Hope this help.

[ChiefSmokeDawg]

Originally Posted by LiveFastDieLast

As said above you will need to remove the vales for inspection.
If they are not visibly bent by eye or with a machinist square you will need some tools like this.

A indexing collet punch grinder


and a Height Guage with Dial Indicator attachment


A extremely flat surface will also be needed, A granite inspection table is the best but something level and flat should work.

The Valve will go in the Indexing Holder. Set the height gauge on the valve. and rotate the holder. This will give you a read out on the indicator and you can see if the valve is bent. You will see the dial indicator read from a positive to a negative number back and so on.
Or you will see very little movement on the gauge.
I have no idea what type of tolerance Yamaha has on the Valves but almost all dial indicators read out to .ooo1 of an inch

If you have any Tool and Die or machinist friends that will be the quickest way to get access to those tools.

Hope this help.

I don't think I'd buy ANY precise measuring tool off alibaba...

[LiveFastDieLast]

Originally Posted by ChiefSmokeDawg

I don't think I'd buy ANY precise measuring tool off alibaba...

Just a photo for example. but I agree. I didn't even notice the name.. hahha

[paan009]

I have an auto race shop available to me.
Just these bike parts are so small compared
to the V8's they build!

[MELK-MAN]

what about the valve buckets for those 2 valves? Are they cracked? (the things the camshaft lobes hit to push the valve spring/valve downward). IF so, the head is JUNK.
If the valve is just bent, and the bucket easily comes out from on top of the spring, i suspect you can use a spring tool to remove the retainer/keepers, take the spring out, then beat the valve out. From there just replace the valve guide and valve..

[paan009]

Buckets looked good, but I'll pull valves out and check