how do you bend 4 inlet & 2 exhaust valves gs550?

[completecaferacer]

just bought a non running gs550 for spares , no compression at all.

can see daylight through all inlet valves. when head removed and shining a light over valve. when taking all valves out we found 4 inlet bent and  2 exhaust bent.

valve timing was correct

cam chain tension was good

how has this happened? i dont have a clue - its only going to be used for a spares bike  i would like a postmortum

[Captain Chaos]

any marks on the pistons?

My guess is over-revving after a furious down-shift

[completecaferacer]

no marks on pistons the tops were quite clean - i thought a missed gear at high revs but why that combination? im confused!!

[markfoggy]

Head swap and a sell on.

[completecaferacer]

8 hours ago, markfoggy said:

Head swap and a sell on.

Nope. I need it for spares for my other gs550s. Just trying to work out why this has happened

[Joebloggs]

Just clutching at straws but could hydraulic lock bend the valves without them touching anything or the cam shaft timed so both in and ex valves open simultaneously and they met in the middle (very optimistic guess lol)

[completecaferacer]

56 minutes ago, Joebloggs said:

Just clutching at straws but could hydraulic lock bend the valves without them touching anything or the cam shaft timed so both in and ex valves open simultaneously and they met in the middle (very optimistic guess lol)

cam timing was spot on - my first thought, it did smell of old fuel in the bores maybe it did hydraulic lock - dont know if that would bend valves but ive seen bent rods from it

[Gixer1460]

Seriously? You can't hydraulic a cylinder if the valves are open and you'll only bend them if they are! Over-revving doesn't need piston contact to occur (although it usually does) any valve float could catch one with the other or they've got overheated - ign timing wrong or lean mix?

[markfoggy]

Sorry, I meant could the bike that you've bought have been used as a donor for a head in a previous life and a shot away head been fitted to make it appear complete.

[completecaferacer]

4 minutes ago, markfoggy said:

Sorry, I meant could the bike that you've bought have been used as a donor for a head in a previous life and a shot away head been fitted to make it appear complete.

You could be right there.i never thought of that 

[Reinhoud]

If it hydraulic locked the conrods would have been bent.

[completecaferacer]

I thought that. If the valves open it cant hydraulic lock as the fuel will not be contained

[completecaferacer]

On 01/09/2016 at 1:46 PM, Gixer1460 said:

Seriously? You can't hydraulic a cylinder if the valves are open and you'll only bend them if they are! Over-revving doesn't need piston contact to occur (although it usually does) any valve float could catch one with the other or they've got overheated - ign timing wrong or lean mix?

Never thought of valves touching each other when over reved. Cheers you might have solved my mystery

[johnr]

perhaps some ham fisted monkey was trying to set the motor up and didnt have the valve timing right when they turned the motor over either by hand or on the starter.