Broke a valve while swapping chain tensioner *Updated 1st Post*

[Blueknyt]

Yes, guides typically are best installed by a shop, they are pressed in much like the valve seats are. But mainly as they have the tools on hand to knurl or ream the guide to fit the valve should it malform any during installation and thus insuring proper fitment to the stem.    its also alot easyer to let them remove the broken guide as they are less likely to damage the head doing so. 

[sledge]

Replacing guides and seats is not something to try at home. Seats and their faces need to be machined true to the guide after fitment.

http://classicmotorcycles.about.com/od/technicaltips/ss/Replacing-Motorcycle-Valve-Guides.htm

http://www.enginebuildermag.com/Article/58992/valve_seats__machining_guide.aspx

[Snake2715]

And to not discount cheetahman maybe I should test the intake valve on that side for leaks?

Not sure how I can do that really given the exhaust is not seated and when i fill the depression with fluid it will leak out the exhaust valve...

If I pull the intake valve should I be able to tell if its bent? Or would the prussian blue on the valve and seat tell me if its bent?

Just some thoughts before I place my orders. I may also check if a valve tool is available locally for rent.

[gsJack]

Lapping the valves will confirm they are not bent and are sealing. You can if you want turn the head with the port up and put water in the port to test seal.  cheetahman is probably right on suggesting the valves clashed.  My intake was knicked on the edge but not bent when the exhaust broke caused by exhaust being held open by stuck bucket and not due to loose chain as in your case.

[sledge]

If I pull the intake valve should I be able to tell if its bent?

Only if you can detect  0.01mm by eye 

You need to check the stem (in several places), the face and the seat for run-out with a DTI

Decent shops use a jig like this one.....

If you want to do a leak test with a valve missing plug the exit with putty and DONT use water, use paraffin, it penetrates better than water, it doesn't cause rust and it wont cause any harm if it finds its way into the engine 

[Snake2715]

Soo.. should I just replace the intake and exhaust valves. I mean maybe thats easier than paying a shop to check that valve?

[gsJack]

Lapping the valves will confirm they are not bent and are sealing. You can if you want turn the head with the port up and put water in the port to test seal.  cheetahman is probably right on suggesting the valves clashed.  My intake was knicked on the edge but not bent when the exhaust broke caused by exhaust being held open by stuck bucket and not due to loose chain as in your case.

[sledge]

Lapping the valves will confirm they are not bent and are sealing. You can if you want turn the head with the port up and put water in the port to test seal.  cheetahman is probably right on suggesting the valves clashed.  My intake was knicked on the edge but not bent when the exhaust broke caused by exhaust being held open by stuck bucket and not due to loose chain as in your case.

You cant effectively lap a bent valve Jack....... think about it.

Ask yourself a question.........what is going to happen as the valve rotates in its guide if the sealing face is not at exactly 90deg to the axis of the guide 

This is the procedure below, anything else is guesswork. Note the service limit is 0.03mm, or just over 0.001"

http://www.motorcycleinstitute.info/suzuki-gsx400f/valve-stem-runout.html

Shops use the jig/DTI method for good reasons, its quick its simple and it removes all doubts

I wouldn't be happy with a cracked guide, cracks have a nasty habit of spreading!

O/P??
Used GS5 heads are not exactly thin on the ground.....personally I would find a good one, clean it up, lap the valves, fit 4 new seals and set the clearances BEFORE fitting it to the engine but hey.......its your bike,time, money etc etc

[The Buddha]

Lapping the valves will confirm they are not bent and are sealing. You can if you want turn the head with the port up and put water in the port to test seal.  cheetahman is probably right on suggesting the valves clashed.  My intake was knicked on the edge but not bent when the exhaust broke caused by exhaust being held open by stuck bucket and not due to loose chain as in your case.

You cant effectively lap a bent valve Jack....... think about it.

Yea bent = cant be lapped ... therefore lapping a valve = not bent ...
However I dont like lapping @ all ... 3 angle cut is far better and around here pretty cheap, car engine shops will gladly do it for you on a bike head.
Cool.
Buddha.

[gsJack]

"Jack....... think about it"

[Blueknyt]

" 3 angle cut is far better"

The valve still gets lapped, the extra angles is to smooth the flow from port to chamber and vice versa past the narrowest contact point of the valve face and seat. 

[sledge]

"Jack....... think about it"

I am sorry old son.......but `guesswork` and the `if it looks ok it is ok` way of diagnosing faults and identifying issues are not methods I generally follow and certainly and more importantly not methods I would recommend to others.

However.......... I appreciate you dont share my way of thinking 

[gsJack]

I'm not guessing at anything.  Lapping in all valves will prove them to be straight and to have good seal, if they won't lap in a bent one will be obvious and will be replaced.  You should be able to comprehend that!  Buddha tried to point that out to you above:

Yea bent = cant be lapped ... therefore lapping a valve = not bent ...

Cool.
Buddha.

[Janx101]

errr... way i read it ...you both mean the same thing... just different approaches/descriptions to how/what process to identify and correct..

bend/s at any point mean they cant/shouldnt be used... ??!

lapping with a machine/lathe/whatever the heck is the name for the thing .. should show if its bent? .. if it is able to be lapped then it cant be bent!?

its a self identifying process to me...

like having any less than perfectly centred item on a lathe .. the eccentric rotation will show itself ..



Jacks version has the lapping showing the eccentric motion ... Sledges version has the Jig testing showing it ...

then again ive not done either... and have the temerity to say something about the process... so 

[gsJack]

Post deleted.  Personal attacks against Moderators will not tolerated.

[sledge]

I'm not guessing at anything.  Lapping in all valves will prove them to be straight and to have good seal, if they won't lap in a bent one will be obvious and will be replaced. 

But Jack?.......take it a stage further, what will a bent valve do to a sound seat when you try to lap it?

Have you ever actually seen the outcome?.......Here is an example for you or for that matter anyone else that is interested 



Notice the wall and face thicknesses at the indicated points.

I don't know if the person concerned actually managed to get a seal but what is obvious and cannot be denied is that the seat was ruined in the process

Care to comment, or do you believe off-centre seats are acceptable? Maybe it wasn't an issue back in your day, I dunno, like you say I wasn't around back then   

So lets summarise, do it the quick easy and recognised way using a DTI, or do it your way and take the seat out in the process.

For the benefit of the younger and less experienced amongst us I suggest somewhere back there you add a disclaimer, something along the lines of this should do.....

**WARNING**...Following my methods may result in you having to replace an otherwise sound seat, following manufacturers and professional engine rebuilders recommended methods wont.......its your call 

[gsJack]

I have related to the OP how I repaired my then 02 low mileage GS head by replacing it's broken exhaust valve, lapping the mating intake valve to confirm it's seal, and putting it back together with new head and base gaskets.  It's run like new for another 80k miles since the repairs so I'm satisfied with them.

If the OP choses to believe your distorted off center picture as the possible result of a quick lap to check seal then I think his choice might be to just get a new intake valve for left cylinder with the bent exhaust valve as he has suggested himself and be done with the problem.  His bike, his choice.

In the meantime I have wasted more than enough time on this thread and on you and am done with both.  If anyone else cares to offer their opinions to the OP on this repair please do so.   I'm going to go put some more miles on my nicely running 02 GS to get it over the 100k mile mark only a few hundred miles away.  It's rings are getting quite tired but it's valves are still ready to go!   

[sledge]

I agree jack.

Let the people decide.


Coming up next week.........How to bore a straight hole with a bent drill bit 

[Snake2715]

Sorry I have been not been reporting here and thanks all for the input. Life gets crazy sometimes and I didn't get back to this as soon as I had originally planned.

OK so the intake is also leaking with the liquid test. I filled the port and let it sit on its side and it did slowly leak. I think at this point I should just replace it and be done. So both left valves get replaced. The right intake actually was fine as I filled it with liquid while I was at it, no leaks.

I will call a shop I am familiar with in the morning and get the guide price quoted and the parts on their way. I can rent a valve removal tool and will do so. The valve seals I may replace as well I will decide when putting my OEM order together depending on totals.

I am going to order:
Base Gasket
Base Gasket orings x4
Head Gasket
Intake Valve
Exhaust Valve
Valve Guide
Guide Ring (do idea if this is reusable so will get new)
Valve Seals X 4




I assume that once I get this done I will have to re assemble then check clearances and then once again potentially replace shims, such is life.

[Blueknyt]

"I assume that once I get this done I will have to re assemble then check clearances and then once again potentially replace shims, such is life."


yes you will, and check all 4 on clearences once the head is installed and torqued to spec