Quote from: Snake2715 on August 12, 2013, 11:32:08 AM................................The intake valves all appear seated. The right valve is seated or appears so, its guide is ok. The left valve (piston is down as of now) is actually the one with the cracked guide and does not appear seated........................

OK, good news I think, both intake valves appear seated, the right exhaust valve appears seated, the left exhaust valve is the one with the cracked valve guide and doesn't appear seated.

I'd proceed with the water valve check and if it looks good put in cams and tensioner and proceed with a compression test.

If that exahust valve is not seated what happens then? I presume low compression on that cylinder?

I would still need to replace that valve or guide I presume then? Possibly even that seal?

I will research the water test and perform that then.

if the cams are not in the engine and a valve does not appear to be seating, then as the Red Queen says " OFF WITH HER HEAD!"  at least one valve needs servicing to run again.   HOWEVER...........................................  that is the quick dirty way. service the entire head at one time,  Even if you chose to replace the head, i would still have the replacement head re worked... the valve seats dressed (as i dont own the tool i would have a shop do it) along with checking and replacing any valve guides seals and laping in the valves.

um jack, the liquid test is done with head off the engine mainly so it can be cleaned up and not find its way into the crank case via piston rings.  often a liquid like petrol,acetone,paint thinner is used instead of water so it will completely evaporate

Quote from: Blueknyt on August 12, 2013, 06:28:57 PM
if the cams are not in the engine and a valve does not appear to be seating, then as the Red Queen says " OFF WITH HER HEAD!"  at least one valve needs servicing to run again.   HOWEVER...........................................  that is the quick dirty way. service the entire head at one time,  Even if you chose to replace the head, i would still have the replacement head re worked... the valve seats dressed (as i dont own the tool i would have a shop do it) along with checking and replacing any valve guides seals and laping in the valves.

um, thread title starts with Broke a valve while.................but we have yet to see any indication of a broken valve.  Now we have a valve that does not appear seated but Snake still asks If that exhaust valve is not seated.............

If that were my engine I would now want to confirm whether or not that valve might be bent before pulling the head.  I've looked at the two pics Snake posted looking into the port I can't tell whether or not it's seated.  Can you?  I would test the left exhaust valve seal with water and if it leaked " OFF WITH HER HEAD!"

If not I would turn the engine the small distance required to get the right cylinder on the timing mark, install cams properly timed, and make sure the chain tensioner was installed and functioning.  Now the engine can be turned a couple turns to check it and then cranked for a compression test.  If it passes button it up and go for a nice ride, if not " OFF WITH HER HEAD!"

There have been suggestions to lap or grind all the valves, replace all the valve seals, and even put in new rings while in there.  The engine only has 8800 miles on it!  I'd replace the bent valve lapping it in and be done with it.   In fact that was what I did when my 02 had a broken exhaust valve caused by a tight bucket at 20k miles, I replaced the broken valve and it is about to turn 100k miles now with no further engine problems.

Quote from: Blueknyt on August 12, 2013, 06:33:41 PM
um jack, the liquid test is done with head off the engine mainly so it can be cleaned up and not find its way into the crank case via piston rings.  often a liquid like petrol,acetone,paint thinner is used instead of water so it will completely evaporate

um, in this case I'd test it on the engine at least the suspect valve and maybe all.  A little water won't hurt it, water is a natural byproduct of internal combustion and water in the oil is natural until oil is hot enough to burn it off.  I'd change the oil after it's all done and buttoned up, preferably before start up.
My 02 may be the first GS I've pulled a head on but not the first bike and I started overhauling car engines 65 years ago.  I could tell you stories about things like putting the wrong head gasket on a car engine and filling the crankcase with water but I won't bore you with that stuff.   

Jack, i love ya brother. we are just 2 diff schools of thinking on it.  I wont leave a cracked valve guide to chance, the head comes off my bike toot sweet. its worth a gasket set to me to replace the valve guide and service the valve that sits in it.  for giggles i will toss on fresh valve stem seals as a set and check the seating area of the other valves with some  prussian blue.  might re lap them all if im feeling anal about it.   so, take it for what its worth.    its my 2cents

Final decision is Snakes on which way to go, it's his bike and he has to live with it.  We can only advise what we would do.   

love all the info. i will be back on this shortly.

I am most likely going back to old ways and will pull the head. I can see the gap around that valve so its not seated. I do know that.

I don't know which of this work I can do and which my local shop gets. That I will figure out when I pull the head.

the water/naptha/whatever test on bike is very good advice. you can use a drinking straw to only place a few drops directly on the valves, then look through the spark hole for evidence. if you use something like radiator coolant and a black light... bam, it can't hide. don't let it sit though, do it, then flush with fuel or oil, and dump the oil afterwords, before running the engine.


lots of bikes have cracked valve guides, for who knows how many miles.

if you do pull the head, flip it upside down and fill the depression of the head with a penetrant oil, then watch the runners for drips. any sign of leaks =bad valve faces and or seats. mark the leaky ones with paint pen, and check it again a few thousand miles later on the bike as described above. if there is a lean condition, it will do similar damage again quickly.

I know I am late to this thread but I think the valves in number two hit each other due to extreme cam chain slack.  That could be the reason the guide is cracked.  It would also explain the exhaust not seating, and the poping noise as they hit, and were forced past each other.  Chances are the intake and the exhaust valves are both bent.  If the valve hit the piston, the mark could be extremely tiny.  The size of an ant or smaller.  That's hard to see looking down a plug hole.   You can do a compression test but you could also do further damage if that exhaust valve is bent and stuck open and/or, not moving correctly.  If it were me, unfortunately, that head has to come off at a minimum.  Good Luck

Engine was sitting with cams and tensioner removed and right piston near TDC and Snake was reporting both intakes and right exhaust seated but left exhaust questionable.  I suggested the water test (best described by ohgood above) be done to check status of left exhaust valve before turning crank and assembling cams and tensioner for compression test, was still questioning removing head at that point until status of left exhaust was confirmed.  Snake has now reported the left exhaust is open and all are now in agreement so  "OFF WITH HER HEAD!"










"OFF WITH HER HEAD!" is a creation of Blueknyt but not copyrighted.   

off with her head..

So what do I do with cam chain exactly?

Back (carb side) cam chain guide stay in or remove the bolts and it before pulling head?

lastly...how do i separate the top and bottom of the head? it seems to want to come off together.. I have that front bolt off by the exhaust... pry it apart in a fin? tap on side with a rubber mallet?

"OFF WITH HER HEAD!" is a creation of Blueknyt but not copyrighted.   


just wanna state that i used a quote from a charactor in a story, i in no way take credit for the creation of said quote fictional or otherwise...

as to the chain and tensioner, remove the tensioner,  I used a  bit of wire coat hanger in the link of the cam chain the first time to make sure i could fish it out if it fell deep, but it doesnt go far into the valley if you let it drop and you can easely fish it back out.  small bolt front of engine between exhaust ports , remember to remove that one? dont think there is one  by carbs, not on this engine anyway.   then book says use a rubber hammer gently on sides to bump the head and seporate from the cylinders  .    just be careful and take your time. you dont want to marr the head or break anything

ok good so I can let that chain drop, but need to be able to fish it out. soon we will see what lies beneath....just not tonight.

Pics galore in the updated first post...

So I take it I need to do a leak test now with the head off?


Hows it all look?

Somebody correct me if I am wrong but I think I can see a shiny spot on the intake valve where the exhaust valve nicked it.  I don't think the piston is involved.  But then, I never thought it was.    I think this is a case where the valves hit each other due to excess cam chain slack.

Decision time now before proceeding.  Blueknyt seems to feel strongly about replacing that cracked exhaust valve guide but I'd let it go as I did with my own and and then had another 80k trouble free miles with a piece of that guide tip missing.  ohgood whose opinions I value in these matters offered:

Quote from: ohgood on August 14, 2013, 06:23:00 AM
lots of bikes have cracked valve guides, for who knows how many miles.

Also, you mentioned buying a new head gasket but didn't mention the cylinder base gasket which many feel should be replaced when it's disturbed by pulling the head.  I didn't replace it when I replaced a leaking  head gasket on my CM400 years ago but did replaced it when I repaired my GS500 broken valve and it leaked a wee bit on both which doesn't bother me as much as it might you.

Your bike, your choice now.  Finally the Proof:



If that were my engine I'd do it like I did mine, it has less than 10k miles on it, repair the damage an get riding again.  Little need for a water test now, replace the bent valve and lap in all 4 of the valves to confirm good valve seal on all.   You'll need a valve spring compressor to r&r the valves.  Clean up the carbon as good as possible all around and put it back together. 

I wouldn't bother to change the valve stem seals either, didn't replace them on my own bike and am at 99.5K miles now with no signs of a valve seal problems.  The old, tired, worn, rings are a different story that I think I should report on soon.   

Others would disagree and recommend further work while you have it apart and I'd welcome their opinions.

Ok heres the questions:

For Tools I need:

Valve spring compressor:
http://www.amazon.com/motorcycle-valve-spring-compressor-tool/dp/B004NV21YA/ref=sr_1_11?ie=UTF8&qid=1377214142&sr=8-11&keywords=valve+spring+compressor

Valve Lapping Tool:
http://www.amazon.com/Lisle-21200-Small-Valve-Lapper/dp/B0009OR99C/ref=sr_1_1?ie=UTF8&qid=1377214173&sr=8-1&keywords=valve+lapping+tool

Prussian Blue:
http://www.amazon.com/Permatex-80038-Prussian-Blue-Tube/dp/B000HBM86Q/ref=sr_1_1?ie=UTF8&qid=1377214268&sr=8-1&keywords=prussian+blue

Valve Grinding compound:
http://www.amazon.com/Permatex-80036-Valve-Grinding-Compound/dp/B0002UEOMS/ref=sr_1_3?ie=UTF8&qid=1377214308&sr=8-3&keywords=valve+compound



For OEM Parts I need:

Cylinder Gasket 11241-01D00

Cylinder Head gasket 11141-01D11

VALVE, EXHAUST 12912-01D00

Valve Guide 11115-45740

Valve Guide Ring 09381-10003


Do I need to replace these parts?:

O RING, CYLINDER HEAD
Part# 11143-06B00

Copper washers between the head and bolts?


On "Bent" valve do I need to replace the seat, oil seal, springs retainer, cotter valve? Or wont I know until its off, or should these be ok?

What is recommended to clean the carbon off the pistons and head anything specific? I watched a guy use oven cleaner once on a car engine but have no idea if that was a good choice.

Also I presume I should remove the valves and inspect and post here before placing my oem parts order. Are the tools listed above what I need to do the job?

I have already given my advice in prev posts,   jack and I are 2 diff schools on how to treat it.   you are going to have to choose for yourself on what you should do. If you havent yet, get a repair manual as it can answer alot of questions.   I will not get into a info tug of war with another twins member whom i respect.  i will just agree to dissagree.

I'd order a head gasket including the four o-ring seals, the cylinder base gasket, and the exhaust valve.  I didn't replace the copper washers under the bolt heads although some do.  Should be all the parts you need, might as well get them on the way.  If something turns up later you can get it later.

I borrowed a valve spring compressor from my son, got a tube of valve grind compound locally, and lapped in the valves turning them with my thumb.

I see you are ordering a valve guide, I've never tried changing one and would probably take it to a shop to be done if I had too but didn't feel it was necessary when I did mine.  I wouldn't have the shop grind seats unless you find them really bad, you will loose valve adjustment range you might need later.  Your valves/seats on your low mileage engine should be good as new with the lapping.

If you'd feel better putting in new valve stem seals do so, they only cost a few bucks and it will be easy to do while you're lapping the valves.

I used a scraper and a wire brush to clean carbon as good as possible in my current non electric garage.  In the auto garage we used a wire brush in a drill motor to clean carbon out of the combustion chambers and brushed the valves clean with a big wire brush on a bench motor.

Final decisions can be made after you take the head apart and confirm the condition of the valve and seat faces.  I agree with Blueknyt's suggestion to get a manual, it will answer most of these questions for you.