Topic: copper gaskets and cylinder protrusion

[paulages]

I'm having a dandy of a time getting my head gasket to seal up after installing a copper head gasket in order to get the compression where I want it. I hoped it was just a matter or re-torquing the head after a heat cycle, but the leaking was bad. I tore it back down, and the carbon shows the leaks quite clearly. The leaks are between 1-2 and 3-4, and in a few places over to the stud holes, which is where it was puffing out.

Before this last install, I had the cylinder surface milled to correct unevenly protruding and recessing liners, having had to remove them when I had the block porosity-sealed. It looked nice and purty, and to be honest I can't remember if I double checked the work.

In any case, the liners are now about .002" shy of the deck. I don't know whether the liners settled or the machinist didn't cut deep enough, but the machining marks on the faces line up and make me suspect the former. Anyway, am I correct in thinking that the copper gasket will seal best with the liner neither protruding or recessing? Should I give up on the copper gasket and just use the composite gasket and live with the half-point drop in compression? should I drop this thing off of a bridge? 

[Hasenkopf]

I would think it should be flush... the gasket has to seal against the cylinder liner, and the head.

[RAFster122s]

Unless you are torquing to the point of deforming the gasket and making it thinner in some areas the area around the cylinders won't seal or will barely seal.

Sounds like you need a chat with your machinist with the visible proof you have and have him skim some more off the cylinder/liners until it is all flat as you asked. Not that you need a come to Jesus talk with him as is sometimes referred to but you can show him the evidence you have that shows it to not be right and ask if he would consider doing it gratis, if not free, then at minimum discounted as it wasn't what you asked to be done or something else has gone wrong.
You have the set screws on the cylinder to sleeve interfaces to lock them togehter if I remember correctly. So, unless something isn't assembled correctly then it is as you are pointing out, something else was wrong with the machining and it was not cut low enough.

Don't abandon it, you've come too far to do so...just remember engine builds sometimes have teething pains...give it some time and a bit more money to mature as needed and you will achieve the goal you set out to achieve.

David

[Terry in Australia]

Drop it off a bridge mate, and post pics!

But seriously, are you saying that the sleeves have "settled" slightly below the mating face of the cylinder block? If so, it's not the machinist's fault, it's just that when it go hot the liners have dropped completely into their recesses' and the block just needs to be machined again to make everything level. if this is going to bump the compression up too high, you might need to use a thicker base gasket to make up the difference.

Also, you could think about "O" ringing your sleeves, i.e., cutting a shallow groove around the top of your sleeve and tapping in some copper wire to form a raised "ring" which will bite into the head gasket and help it seal better, this was something that all the racers did "back in the day" and my 1060cc RC block sleeves are all "O ringed" for that purpose. Lucky for you it's a 550 and you don't have to pull the engine every time you have problems with your top end! Cheers, Terry.

[bwaller]

After the sleeves are reinstalled they should be touched in a press to be sure they've bottomed out. That likely didn't happen and they did in fact settle. (I think they should still go in a press to be sure they've completely bottomed) It was probably the cause of your leak, so in theory the copper job should seal now.

If you take another 0.002" off the deck then your 0.043" composite gasket becomes 0.041 and you lose less.

Sorry Paul.....not funny man.

[paulages]

i did think about o-ringing it, but that's best done in a lathe when the liners are out. at this point, it's not likely... at least until i need to tear down again.

i thought about it after i posted, and i think the liners were protruding about the equivalent to the recess now, so it makes sense that they settled equal to the amount machined off last time. the machine shop i always used shut down for business, but they'll still do stuff for me. i'll drop it off in the morning and have the cylinder surface decked, and may have the head re-surfaced just to be sure. i haven't had any time to deal with it all summer, but i'd like to get a little riding in...

[Terry in Australia]

G'Day Paul, there is a tool that you can buy to cut the grooves with the liners in the block, I saw a used one on EBay a year or two ago but didn't need one, so didn't buy it. I'd like one now though, so if you see one, let me know? Cheers, Terry.

[754]

 Boring head in a mill will cut the grooves.

 I think a lot of engine shops go crazy decking, easy to go to far.. plus not all will run a dial test all around and take care to level the block.

 For 2 thou, I think I would get a big piece of sandpaper on surface plate, or lapping plate and have at it.. work it off by hand..

[paulages]

Boring head in a mill will cut the grooves.

 I think a lot of engine shops go crazy decking, easy to go to far.. plus not all will run a dial test all around and take care to level the block.

 For 2 thou, I think I would get a big piece of sandpaper on surface plate, or lapping plate and have at it.. work it off by hand..

true, but i really want this to be done and buttoned up. i'd rather pay to have both surfaces decked and know that it's right.. i just have to make sure the right person does the work and it'll be fine. i'll inquire about the cost of having o-ring grooves cut with a boring head.

[turboguzzi]

hei paul

would deck everything and then compensate with a thicker base gasket if need.

that said, im afraid that cooper gaskets are not as compresable as stock ones, so they will start sealing well only after the motor is really hot and the cyl has expanded a bit. I warm up my motor really well before startign to pile up the coal. also, the copper cant sink into the micro grooves casued by the fly cut, so try and get from your machinist the best possible finish. even with everthing done right cooper gaskets will show some leakage marks.

TG

[paulages]

hei paul

would deck everything and then compensate with a thicker base gasket if need.

that said, im afraid that cooper gaskets are not as compresable as stock ones, so they will start sealing well only after the motor is really hot and the cyl has expanded a bit. I warm up my motor really well before startign to pile up the coal. also, the copper cant sink into the micro grooves casued by the fly cut, so try and get from your machinist the best possible finish. even with everthing done right cooper gaskets will show some leakage marks.

TG

thanks yossef,

dropping the block off today, and we'll see what they can do. the copper spray should help with the micro grooves, no? in any case, this leak was bad enough that exhaust smoke could be seen puffing out between the cylinders...

[MRieck]

hei paul

would deck everything and then compensate with a thicker base gasket if need.

that said, im afraid that cooper gaskets are not as compresable as stock ones, so they will start sealing well only after the motor is really hot and the cyl has expanded a bit. I warm up my motor really well before startign to pile up the coal. also, the copper cant sink into the micro grooves casued by the fly cut, so try and get from your machinist the best possible finish. even with everthing done right cooper gaskets will show some leakage marks.

TG

thanks yossef,

dropping the block off today, and we'll see what they can do. the copper spray should help with the micro grooves, no? in any case, this leak was bad enough that exhaust smoke could be seen puffing out between the cylinders...

Copperkote will help. I'd oring the sleeves too Paul

[paulages]

hei paul

would deck everything and then compensate with a thicker base gasket if need.

that said, im afraid that cooper gaskets are not as compresable as stock ones, so they will start sealing well only after the motor is really hot and the cyl has expanded a bit. I warm up my motor really well before startign to pile up the coal. also, the copper cant sink into the micro grooves casued by the fly cut, so try and get from your machinist the best possible finish. even with everthing done right cooper gaskets will show some leakage marks.

TG

thanks yossef,

dropping the block off today, and we'll see what they can do. the copper spray should help with the micro grooves, no? in any case, this leak was bad enough that exhaust smoke could be seen puffing out between the cylinders...

Copperkote will help. I'd oring the sleeves too Paul

i think that's in my future, mike. i want to make sure it's done right though.

[kos]

Hey, get that cylinder block over the river there to Vancouver, WA to LES shop and he'll make it right. Les Barker of Little Eng Services.


And btw...what you using copper for anyway. Never ran one yet in any CB750's I have ever built or raced.and fixed all our AHRMA CB350 head leaking problems by doing the same thing. Not needed and only Good for very high compression engines with ultra high cylinder pressures...like drag racing engines. And they take those down all the time, and they put up with oil leaks, weeps and seeps.

KOS

[NitroHunter]

Did you anneal the gasket - yourself - prior to installation?
Sometimes they can be pretty stiff when you take them out of the box, it's my opinion that our bike's puny head studs are barely adequate to provide enough clamping force for a decent seal as is.
A dead-soft copper gasket should conform to every little imperfection, and being down only .002" at the sleeve isn't that much, considering that they squish over and around "O" ringed sleeves while also making a leak-proof oil passage seal.
As far as worrying about a micro finish on the head/deck surface, I have seen a correctly prepped gasket (torqued to 22 ft-lbs on a 750) conform to, and even embed itself into even a very rough, poorly flycut finish. A slightly rough surface provides a better gasket 'bite' than a mirror finish.
 
I even have a much-used Accutronix copper head gasket on a stock 750 motor that has never leaked, I used copper coat and annealed it just prior to install. I heat it red hot with the torch, then drop it strait into a tub of cold water. It is almost scary soft when lifting it out.  

I've used copper head gaskets on all of my big bores - and I damn sure refuse to accept ANY weeps or seeps on my turbobike!  

[paulages]

KOS-

les doesn't do head work, but rather sends it to Baisley's, which is a block from dan hall's (which i use). baisley's is a great cylinder head shop, but a little pricier. DH's fixed this for free, since it was their error. I just had to make sure the right person did the work. 

they took .004" off of the deck, and .003" from the head. I was running the copper gasket in order to get the CR where i wanted it (cometic won't make a composite gasket less than .043" thick). however, the piston shoulder will now be .004" above the deck, and the head combustion chamber will be a tad smaller. before the milling, the composite gasket gave me a 9.95/1 CR, and the copper gasket 10.5/1. I should be somewhere in between the two now with a composite gasket, so I'm happy. Also, the guy who fixed it told me the other machinist had not gone far enough, and there was a low spot at the cam tunnel, which explains where the oil was coming from at the leak.

GOT IT ALL BACK NOW! i'll let you guys know the result in a few hours...

p.s. to NitroHunter: yes, the gasket was annealed well, both from cometic and again by me.

[Terry in Australia]

Hey Paul, are you using puny 550 head studs, per Nitro's post? I presume that you've had some H/D studs made if you're running such high compression? Cheers, Terry.

[paulages]

Hey Paul, are you using puny 550 head studs, per Nitro's post? I presume that you've had some H/D studs made if you're running such high compression? Cheers, Terry.

i'm actually using a combination of APE HD studs and stock cb650 bolts (the APE cb500/550 kit doesn't quite work with the 650 head), both of which torque to 22 ft#.

[Terry in Australia]

No worries mate, I couldn't imagine that you'd use the stockers. Cheers, Terry.

[Retro Rocket]

Hey, get that cylinder block over the river there to Vancouver, WA to LES shop and he'll make it right. Les Barker of Little Eng Services.


And btw...what you using copper for anyway. Never ran one yet in any CB750's I have ever built or raced.and fixed all our AHRMA CB350 head leaking problems by doing the same thing. Not needed and only Good for very high compression engines with ultra high cylinder pressures...like drag racing engines. And they take those down all the time, and they put up with oil leaks, weeps and seeps.

KOS

Hi mark {sorry for the hijack Paul}, what type of gasket would you recommend then?

Mick

[Big Jay]

Send me the block and we will make it right.

Jay

[paulages]

Send me the block and we will make it right.

Jay

Jay... if isn't right after this, believe me I will.

I went to assemble tonight and one of the teflon buttons fell into the cam chain tunnel.  :' ( i pulled the engine and shook it upside-down, but had no luck (except that another fell off and fooled us into thinking we had lucked out...) even if i have to split my cases to get it out, it'll only set me back another couple hours, and I should be able to have it running tomorrow night.

world's only 735cc honda?

[paulages]

WOOHOO!!

well, she's sealed up now. HOLY CRAP, did those carbs wake up the beast. 

[RAFster122s]

Nice to hear you have her running again & the increased fuel is making her a firesnortin' beast|!

[paulages]

Nice to hear you have her running again & the increased fuel is making her a firesnortin' beast|!

she was running fine before, but now she does without hemorrhaging oil! feels great to start first kick...