Quiz of the day - guess a part...

jonarmstrong wrote: Valve seals??

Well, I guess that's about as close as you can get without actually guessing it, so I'll spill it.

I found the crumbs in the pics above rattling around when reinstalling my exhaust today, they're the sad remains of my #3 exhaust valve guide that went missing a year and a half ago.

It all started out with cylinder 3 intermittently cutting out. I mistakenly took it for a carb problem and went through the carbs three or four times, obviously test riding the bike after each attempt like an idiot, only to see the problem get worse.

When it finally dawned on me to buy a gauge and do a compression test I had no compression at all on cylinder 3, time to pull the head. Found #3 exhaust valve bent and dangling with about 1/4" of valve guide and the guide seal still on the valve, the rest of the guide had just vanished until this morning. Luckily the valve didn't break, but it must have slapped around pretty good, the hole where the guide should be was big enough to stick my pinky through.



By some sort of miracle there was no damage whatsoever to combustion chamber, piston or cylinder wall and no debris left in there, it all went straight out - still cost me close to 350 bucks to have a very competent machine shop in the next town weld a bushing in the head, install a new guide, recut the seat and touch up the others. Oh well, could have gone a lot worse I guess, at least it was mildly amusing to finally find the remains...

That is really strange. Glad the damage wasn't too bad.

On the 550's, it's common for a metal choke flap to somehow miraculously make it through the entire combustion chamber, never to be sen again. Occasionally, though, one will get caught in a valve. :pinch:

Wow Bo, glad more serious damage did not occur.

I'm not surprised that none of the pieces got into the chamber. When the exhaust valve is open there's a good bit of pressure heading outward.

Wasn't the bike smoking a good bit?

It's not uncommon to have exhaust guides sink in J heads. Your's was pretty extreme :lol:

I have one on the way to repair for the same problem but not as bad as yours. It should be fixable with the +.027 APE guides 99101-25.


I have seen stock J guides so loose they were actually moving up and down in their bores when the valve moved.

BTW, your spark plug needs to be turned 180 degrees. Get some indexing washers and fix all 4 while your at it.

You might be fine but if you are running cams over 420 lift with stock guides, it's advisable to check your clearance distance between the valve seals and the keepers and/or retainers.

I thought you had a ported head on that bike The valve seat region looks pretty stock to me...

LarryC wrote: I'm not surprised that none of the pieces got into the chamber. When the exhaust valve is open there's a good bit of pressure heading outward.

Wasn't the bike smoking a good bit?

It's not uncommon to have exhaust guides sink in J heads. Your's was pretty extreme :lol:

I have one on the way to repair for the same problem but not as bad as yours. It should be fixable with the +.027 APE guides 99101-25.


I have seen stock J guides so loose they were actually moving up and down in their bores when the valve moved.

BTW, your spark plug needs to be turned 180 degrees. Get some indexing washers and fix all 4 while your at it.

You might be fine but if you are running cams over 420 lift with stock guides, it's advisable to check your clearance distance between the valve seals and the keepers and/or retainers.

I thought you had a ported head on that bike The valve seat region looks pretty stock to me...

Intake port looks ported too me...but yes the seat areas would benefit from blending.

loudhvx wrote: ...On the 550's, it's common for a metal choke flap to somehow miraculously make it through the entire combustion chamber, never to be sen again. Occasionally, though, one will get caught in a valve. :pinch:

Ouch.. :blink: Yeah, like I said, could have been a lot worse especially if the valve had broken - I have a 650 topend lying around where that happened (not to me, got it with a stash of parts in a trade), combustion chamber is busted beyond repair, piston is just a piece of scrap alu, cylinder wall is torn apart and the piston rod is damaged.

LarryC wrote: I'm not surprised that none of the pieces got into the chamber. When the exhaust valve is open there's a good bit of pressure heading outward.

Wasn't the bike smoking a good bit?

That makes sense now that I think about it - and no, it didn't really smoke, not that I noticed anyway.

BTW, your spark plug needs to be turned 180 degrees. Get some indexing washers and fix all 4 while your at it.

Already done, the ones in the pic are just random old plugs I stuck in when I sodablasted the combustion chambers.

I thought you had a ported head on that bike The valve seat region looks pretty stock to me...

As far as I know the engine is bone stock GPz 1100 B2, at least I haven't done anything to it.

Good to see you around again btw.

OnkelB wrote:

LarryC wrote: I'm not surprised that none of the pieces got into the chamber. When the exhaust valve is open there's a good bit of pressure heading outward.

Wasn't the bike smoking a good bit?

That makes sense now that I think about it - and no, it didn't really smoke, not that I noticed anyway.

BTW, your spark plug needs to be turned 180 degrees. Get some indexing washers and fix all 4 while your at it.

Already done, the ones in the pic are just random old plugs I stuck in when I sodablasted the combustion chambers.

I thought you had a ported head on that bike The valve seat region looks pretty stock to me...

As far as I know the engine is bone stock GPz 1100 B2, at least I haven't done anything to it.

Good to see you around again btw.

NIce to see you as well That's amazing it didn't smoke.

This is what's headed my way to sort out

loudhvx wrote: That is really strange. Glad the damage wasn't too bad.

On the 550's, it's common for a metal choke flap to somehow miraculously make it through the entire combustion chamber, never to be sen again. Occasionally, though, one will get caught in a valve. :pinch:

Yep... I've seen that too. Amazing how that can happen. That was a pretty hokey setup on those TK carburetors to begin with.