Smoky XS

[xs650man]

Didn't like the ratty 4 into 1 exhaust on my XS so made a 4 into2 system like the stock but without the cross over pipe. Once warmed up there was smoke coming from the left muffler, checked left two plugs and # 2 black as hell, rest fine. Cant say there was any noticeable smoke with the 4-1 as it would have been diluted, for a better word.
Decided to take the head off to see what's going on, bores all have the same amount of wear, no scores in # 2 like I was expecting and no damaged rings.
Removed the valves from the head and guess what ? Suspect # 2 has a damaged valve guide, the seat for the inner spring is totally smashed and the springs were actually jamed in there hole.
There is also damage to the guide on the other end as well, in the port.
Any ideas what might have caused this ?

[Gmac]

Has anyone

Pulled the valve cover off previously of had any head work done?
The only way I see a spring seat getting honked up is improper assembly.

[xs650man]

The only time Ive had the cam cover off was to paint it, P.O. was a bit of a cowboy tho...

[mack]

damage

can you post a picure of the damage? Check your valve guide seal in your #2 if the head is still off.

[xs650man]

can you post a picure of the damage? Check your valve guide seal in your #2 if the head is still off.

Ok, here is the damaged guide where the inner spring seats,http://i329.photobucket.com/albums/l...seat%20003.jpg. compared to a good guide,http://i329.photobucket.com/albums/l...seat%20004.jpg, here is the remains of the guide flange,http://i329.photobucket.com/albums/l...seat%20001.jpg, here is the damage guide viewed from the port,http://i329.photobucket.com/albums/l...seat%20005.jpg, here is the seal,http://i329.photobucket.com/albums/l...seat%20002.jpg

[mack]

head

I sure looks like the wrong shim size was in that cylinder allowing the base of the valve stem to come up and hammer the base of that guide to pieces. The valves themselves are of harder material. Also from the amount of build up in that port, it looks like the old oil seal failed a while ago. The guides can be replaced but is generally not an option because of the cost. It's cheaper to just get another used head. What did the valve stem show, any damage to that?

[3Phase]

A wag

Over-rev and valve float, '650man?

Even of it didn't bend or break the valve when it kissed the piston could crack the nose off the exhaust valve guide. The valve stem and guide would overheat without the missing valve guide tip and exhaust would flow up into the guide, causing the valve to seize/stick. That'd skew the valve clearance and cook off the valve stem oil seal and the cam would eventually pound the whole enchilada into submission.

.

[mack]

Rpm

Scott, hi man welcome back. If it was high RPM, why only one guide out of eight got toasted? Perhaps xs 650 needs to look at the rest.

[3Phase]

Scott, hi man welcome back. If it was high RPM, why only one guide out of eight got toasted? Perhaps xs 650 needs to look at the rest.

Thanks, Mack, good to see you're still out and about too.

I pictured one of those super-slo-mo shots of someone getting smacked and the ripples, "No-o-o-o-o-o-o-o-o-o!"

Yeah, it's just a WAG -- checking the rest of the valves'd be a good idea if you were going to try to keep and rebuild a trashed head; haven't seen the valve itself, the inside of the valve guide or the valve springs. Were the springs broken or just jammed? The valve seat contact pattern doesn't look too bad but the valve could be bent. What's the runout on the valve stem and the seat/face? I wouldn't use that head again myself, it'd just be something to work on while waiting for another cylinder head that's not FUBAR.

.

[xs650man]

Thanks for all the input guys. All the other guides look good but havnt checked for bent valves yet. Like mack said, if it was over revved why only one seat damaged ? These bikes arnt that common here in NewZealand so finding another head would be a mission. Ive seen a NOS exhaust guide on ebay for US$45, NZ $61 each !

[3Phase]

It's up to you!

How much time and money do you want to spend trying to fix a trashed head?

Sure, you can replace the springs (were they broken or just jammed?), valve, guide and seal but how are you going to fix the mangled valve spring pocket and seat in the head, just buff it out with some Brasso and stuff everything back in? Head gaskets ain't cheap either, how many times do you want to pull the head?

.

[xs650man]

How much time and money do you want to spend trying to fix a trashed head?

Sure, you can replace the springs (were they broken or just jammed?), valve, guide and seal but how are you going to fix the mangled valve spring pocket and seat in the head, just buff it out with some Brasso and stuff everything back in? Head gaskets ain't cheap either, how many times do you want to pull the head?

.

Yes I here what your saying re throwing money at a buggered head.Springs were jammed in there pocket by the trashed guide, not broken. If the motor has been screwed then probably not worth rebuilding. FJ 1100s are plentiful here and a transplant wouldn't be out of the question, was contemplating a chain drive conversion anyway.

[mack]

XS's

There are a bunch of XS'rs in Aussy land and a few where you are. Check out their forums before you give up on it. If you know a good speed shop close, for a few beer one of the techs may be able to help you out. Shipping from here just isn't going to be cost effective!

[3Phase]

A Different Light

Is B.Walker still hanging out around somewhere? He's (was?) one of the Kiwis with an XS11 and probably a little closer than the Aussies.

'650man, the cylinder head might be good, "Don't Panic! (TM)"
I think that steel valve spring seat has been hammered, you need another one.

Check the valve pocket wall and the floor under the steel spring seat. Keep in mind that the valve spring buckets are always supposed to go back in the same pockets -- number them as you remove them so you don't mix them up.

It's tough to see the details in your pictures of valve pocket because the right-hand side of the pocket is in shadow and some parts are overexposed but it doesn't look like there's much, if any, damage to the pocket itself.

I've made a couple of troubleshooting images by cropping your original color JPG images, converted them to grayscale, then embossed them to exaggerate details and highlights:


2015-04-04 Exhaust seat 004_crp_emb

The steel valve spring seat and the oil seal are still in place in the valve spring pocket. What looks like a large dent in the oil seal is just glare from the light but you can see the wear/damage to the steel spring seat.



2015-04-04 Exhaust seat 003_crp_emb


The steel valve spring seat and the oil seal have been removed, this is just the aluminum valve spring pocket and the top of the valve guide. You can see the wear on the walls and and what might be damage to the floor.


So, don't toss the head in the scrap heap just yet, check the valve pocket to see if it's actually been damaged or if it's just marked up!

.

[xs650man]

Is B.Walker still hanging out around somewhere? He's (was?) one of the Kiwis with an XS11 and probably a little closer than the Aussies.

'650man, the cylinder head might be good, "Don't Panic! (TM)"
I think that steel valve spring seat has been hammered, you need another one.

Check the valve pocket wall and the floor under the steel spring seat. Keep in mind that the valve spring buckets are always supposed to go back in the same pockets -- number them as you remove them so you don't mix them up.

It's tough to see the details in your pictures of valve pocket because the right-hand side of the pocket is in shadow and some parts are overexposed but it doesn't look like there's much, if any, damage to the pocket itself.

I've made a couple of troubleshooting images by cropping your original color JPG images, converted them to grayscale, then embossed them to exaggerate details and highlights:


2015-04-04 Exhaust seat 004_crp_emb

The steel valve spring seat and the oil seal are still in place in the valve spring pocket. What looks like a large dent in the oil seal is just glare from the light but you can see the wear/damage to the steel spring seat.



2015-04-04 Exhaust seat 003_crp_emb


The steel valve spring seat and the oil seal have been removed, this is just the aluminum valve spring pocket and the top of the valve guide. You can see the wear on the walls and and what might be damage to the floor.


So, don't toss the head in the scrap heap just yet, check the valve pocket to see if it's actually been damaged or if it's just marked up!

.

B Walker actually owned this XS before the guy I bought it off, who owned it for a very short time which has always made me think why he sold it so quick. When I first picked the bike up it came with some spares in boxes that had Brian's name, address and phone number on them, I got hold of him to get some history on it and he said he had doubts over the new owner. Its been a while since I talked to Brian but i will try to contact him again.
Theres no visible damage to the walls of the spring pocket and only minor pitting at the floor where the broken bits of seat have been trapped under the inner spring, thanks for the greyscale pix ! Someone mentioned bronze guides, are these superior to the steel ones ?