something broke in the cylinder head

[Dawn Light]

these fellas broke all but one i think. they broke down the middle. it's my friend's 94. we were told by the mechanic that these parts were drilled in line with the cylinder head in manufacturing, and thats why you can't order them. any suggestions?

[The Buddha]

Almost ... OK they are alingn bored ... so each one is unique ... However If you do get one that is close enough and put the right ones on ... you might be able to get by ...
Very very important - Treat it like a motor that is being broken in ... 500 miles at low RPM then open and check ... if you dont see galling or scoring, re torque them and you're OK.
I know someone who didn't do that on a GSXR 750 and managed to destroy the head ... He swappd it out and made it through that ordeal fine, only to lose it right after.
Cool.
Srinath.

[coyotee]

or you replace the whole head.

[sledge]

Your mechanic speaks the truth. They are the camshaft upper bearing journals, they are line- bored together with the lower journals which are integral with the cylinder-head during manufacture. Machining them together is the only reliable way of ensuring perfect alignment and concentricity of the 2 bearings. Some people will say they have used 2ndhand items and mixed and matched with success but it really is a hit and miss affair. Ideally you now need a good 2ndhand cylinder head with all 4 upper journals.

[MarkusN]

And next time you put on the valve cover use a torque wrench. (You'll be surprised how low the required torque feels.) Overtorquing is probably what caused those breakages.

Oh, and one more vote for a new (used) head. I got one for about 20 bucks off eBay.

[GeeP]

You'll need a new cylinder head.

The only other option is to have a machine shop make new caps and line bore them on your head.  However, it would be MUCH cheaper to find a used head even if you have to ship it halfway around the workd.

[ignoreance]

http://gstwins.com/gsboard/index.php?topic=28703.0

Go to this post and tell him you want the cylinder head....

[Dawn Light]

http://gstwins.com/gsboard/index.php?topic=28703.0

Go to this post and tell him you want the cylinder head....

it would be a great idea only that me and my friend are in israel . i'm sure we will find one here thanks for all the advice

[ignoreance]

Small detail only about 10kmiles away Im sure the brown UPS truck still delivers there.. Happy hunting...

[badkarma506]

just go to lebanon and steal one.    i'm sure with everything else that's going on nobody is going to care about a cyl head.

[Dawn Light]

this is crazy. they dropped a couple thousand missles on us, everyone has a shelter, maybe a few hundreds died including soldiers. we dropped so much bombs on them i hear there's a MILLION people without roof, thousands died. a 1,000,000 people... i think people in high windows here are sick, twisted, manipulated and weak. i can't comprehend how someone makes a logical decision to put bombs on people.

[Mandres]

It's much the same in the U.S.  Our leaders think it's ok to bully the whole world and drag our country into conflict after conflict.  It's the regular people like us who have to deal with the repercussions.

-M

[Affschnozel]

this is crazy. they dropped a couple thousand missles on us, everyone has a shelter, maybe a few hundreds died including soldiers. we dropped so much bombs on them i hear there's a MILLION people without roof, thousands died. a 1,000,000 people... i think people in high windows here are sick, twisted, manipulated and weak. i can't comprehend how someone makes a logical decision to put bombs on people.

Well when your fanatic enemies around you are getting stronger there's a point at which you must
react to the blows they deliver you or else take it on a chin every time and bear the loses of
your own people lives.The reaction was quick and not well thought trough I'll agree,
but as one who served and serves in IDF I can't bear the occasional suicide blast here and
soldier kidnaped there,I choose to do something to prevent it (Lebaneese didn't do anything to stop Hezbolah so far...)
Sorry for the politics but after barrages of missiles these past days couldn't be silent,
the fact that you enjoy riding motorcycle in this country and feel free is direct consequence of
thousands of soldiers "providing" you that freedom. It's hard when you just want to evolve and enlighten when surrounding
neighbours don't care for themselves and their people with such things and wish us "all the best".......again sorry 

[Dawn Light]

i don't buy that "soldiers providing me with freedom" thing . what's gonna happen, i'll die? freedom is not being affraid. i'm not affraid of arabs , not affraid of terrorists , not of our neighboors , not of what people will say or think. i am free because i conquer my fear. i am free to not join the army , to think for myself, to be myself and i am free to ride a motorcycle.

[WREX]

question back on topic and please excuse my ignorance with how camshaft upper bearing journals work.  

looking at the shape of these things and where they are likely to break (through the centre hole for the valve cover) - what would happen if they were just left there and the engine kept being used?

The 2 bolts on each side of each journal (that bolt into the head) look like they would keep both pieces in place and the half circle shape that they make would be maintained, keeping the cams in place.

I'd guess that the crack would score the cam shaft while it spins and the valve cover could not be tightened down since the crack would likely be through the threaded hole, which brings it's own set of issues, but could it actually be used?  Are there other issues?

I don't have cracked ones myself, nor am I challenging others direction - just curious on how these things work and what the effects and symptoms of them being broken are?


thanks for any info.




btw - maybe the political discussion can start it's own thread in Odds n Ends

[Mandres]

No, you absolutely could not use them if they're cracked or broken.  The force of the cams pushing back against the valve springs would eventually break them off and then you've got catastrophic problems.  The only correct way to solve this problem is to replace the head.  If you can find a set of caps that match the letter you could try them, but you'll need to measure the oil clearance with Plastigauge and make sure it's within spec. 

-M

[sledge]

I am sure there will be many comments but my answer is:
As the caps are now essentialy in 2 pieces they are unable to clamp over and hold the camshaft in postion accurately and with the same strength as an undamaged one. This will result in the clearance between the journal and camshaft increasing, decreasing or becoming eccentric and this in turn will accelerate wear. Despite being dowelled the caps may now also be able to move axialy about the center of the fixing bolt by a small amount, again affecting clearance. The cracks may also lead to a reduction in oil feed to the bearing surfaces and a drop in oil pressure. Cracks will also compromise the overall strength and integrity of the cap and it may well break at its next weakest point under stress. You are correct in assuming the cracked and uneven edges will play havoc with the camshaft journals. Dont forget items like this are made to hundredths of a millimeter and depend on these tolerances for reliable operation.

[WREX]

that makes sense guys.  thanks.

http://gstwins.com/gsboard/index.php?topic=21929.msg212969#msg212969

I read in this past thread that after purchasing a used gs, a guy had his valves checked only  to find one of the journals broken.  in this case then, he would have likely been getting some weird sounds and vibrations and in the early stages of failure, before the obvious catostrophic stuff started to happen?  or would the symptoms be more obvious and immediate?

10 ft/lb of torque (as per clymer) for the valve cover is not that much at all - you'd almost guess these failures would be more common then we hear about, especially after a valvue check without torque wrench gone bad, type deal.  sounds like a pita to get into, espeically without the know how and resources to fix. 


good luck dawn light - the lesson I'm walking away with having read through this, is that we need to be very careful when putting stuff back together after checking valve clearances.  thanks again guys for all the info.  great learning for others and their experiences (and sorry for those of you who have to go through it, but like I said, at least others like myself are learning).