Topic: Any last minute advise on head gasket??

[Rodger]

 I rebuilt the top end of my CB400F last year.  About 700-800 miles in the NE brand gasket failed and I started leak oil at the head gasket.  I bought  a Vesrah  set this time.  I plan on using spray copper coat on the head gasket.  Any other things I should do???  I really don't want to do this a third time!   Thanks for any advise guys!

Cheers,
Kevin

[70CB750]

I would plan on retightening head bolts after a while.

[WhyNot2]

Aren't you suppose to re-torque after a certain amount of mileage?

I'm sorta saying and asking at the same time. Considering you have to pull the engine to do that on most bikes.

[70CB750]

It is considered the best to retighten after some miles but for CB750 - as you said - it means to take the engine out.

The next best practice is to wait a day and retighten head bolts without running the engine, from what I understand it is not as good as bolts going through the heat/cool cycle but it is better than tightening once.

Of course you can spend a week retightening head bolts, quite the area of self realization for the obsessive compulsive of us 

[AJK]

Clean, dry surfaces. I usually clean up the surfaces using emery cloth, both head and cylinder block. Then run over the surfaces with wax and grease remover. Copper coat gasket spray both sides of head gasket, let it sit for 10 mins to go tacky. Install, torque up to upper range of spec. Leave overnight for the gasket to settle and compress, then re-torque back to the same spec, perhaps adding another 1 ft.lb for good measure. Done. You shouldn't need to revisit it.

[flybox1]

I would advise against emery paper and just clean the gasket surface really well.
A dab of acetone on a white rag over the tip of your finger, and continue to go over and over the surfaces until the rag comes up clean.
Copper coat, 2-3 light coats a few minutes apart.
As AJK stated, wait a bit for it to get really tacky, and then install it.
Torque in steps, up to the desired max,  let it set a day. 
Give all nuts 1/2 turn to loosen in reverse torque order, and then retorque in the proper sequence.

[70CB750]

Tighten vs. torque, sorry guys, English lobs me a curve ball every so often.

At least not as bad as the other day using the word testicles instead of tentacles, now that caused some raised eyebrows 

[RJ CB450]

1.  Make sure head mating surfaces are white cloth clean and finished.

2.  Make sure bol holes clean of liquid and dirt.  Run bolts and holes with a thread restoring tool.

3.  I use a nickel metal compound on all my head gaskets.  Like copper, but a bit more heavy duty.  Never had a gasket issue.

4.  Use a proper thread lubricant on threads and flange.

5.  Follow proper torque order.

6.  Run, then just recheck torque.

[70CB750]

I believe torque figures are generally posted for no lubricant, only Novak rebuild manual lists both - I was quite surprised to see that.

That said, I would not lubricate head threads.

[RJ CB450]

I believe torque figures are generally posted for no lubricant, only Novak rebuild manual lists both - I was quite surprised to see that.

That said, I would not lubricate head threads.

Good point.  My engine building started with car race engines in my family so some things (like JIS crosshead screws XS) might not translate well.  If using a thread lube is not recommended, defer to that.  But hydrolock and dirty/corroded threads are big sources of error.  The copper spray should work as well as my nickel stuff.  In addition, we use it on extreme high temp and high pressure environment gaskets in an industrial setting as well.  Working in high salt environments, also prevents gluing and corrosion.  A corroded and pitted head from my original gasket resulted in needing resurfacing on my bike.

[Rodger]

Aren't you suppose to re-torque after a certain amount of mileage?

I'm sorta saying and asking at the same time. Considering you have to pull the engine to do that on most bikes.

That was the first thing I did after it started to leak.  I found all bolts torqued to factory spec 14.5 lb.  The head gasket looks much different on the Vesrah than the Ne brand.  Thicker and its silver in color, odd material.  The NE was just normal black gasket material with the steel ring at the piston opening. 

[Rodger]

I would advise against emery paper and just clean the gasket surface really well.
A dab of acetone on a white rag over the tip of your finger, and continue to go over and over the surfaces until the rag comes up clean.
Copper coat, 2-3 light coats a few minutes apart.
As AJK stated, wait a bit for it to get really tacky, and then install it.
Torque in steps, up to the desired max,  let it set a day. 
Give all nuts 1/2 turn to loosen in reverse torque order, and then retorque in the proper sequence.

Sound advise!!

[Duanob]

Best advice: go with an OEM headgasket. If you can find one. And follow the manual on torque and sequence.

[Duke McDukiedook]

Or a Cometic gasket if you can't get OEM.

[Rodger]

Best advice: go with an OEM headgasket. If you can find one. And follow the manual on torque and sequence.

If you can find the head gasket?  And the price is ridiculous $65 just for the head gasket about $4 each for dowel & orifice gaskets = $16 , $23 for oem cylinder head gasket, & $5 for breather gasket.   Theyre pricey and I am cheap.....BUT that's why I am replacing it now!  The $50 complete gasket set form N/E fail big time!  I hope Versah is better which I've heard it is.  In the end I guess you get what you pay for.  I am sure OEM is the best option, I hope I don't kick myself in a few hundred miles.

[RJ CB450]

If you clean the mating surfaces, bolt and bolt holes, and use copper spray, you should be good.  But, maybe check your deck for trueness.

Also, not sure about your engine, but my dohc450 and my sohc650 both have o-rings for sealing pressurized oil passages.  Might want to check out some parts lists and make sure it isn't something missing.  The combustion chambers of course seal by the metal ring.

[Wobbly]

Best advice: go with an OEM headgasket. If you can find one. And follow the manual on torque and sequence.

+1. Readily available from Honda, often much cheaper on EBay. After the very expensive ($ 79) Cycle X MLS Steel Head gasket failed me after 200 miles ("no leak" my ass), I am back to OEM.

[Rodger]

If you clean the mating surfaces, bolt and bolt holes, and use copper spray, you should be good.  But, maybe check your deck for trueness.

Also, not sure about your engine, but my dohc450 and my sohc650 both have o-rings for sealing pressurized oil passages.  Might want to check out some parts lists and make sure it isn't something missing.  The combustion chambers of course seal by the metal ring.

Now that its apart the oil orifice is where the leak was.  I used new O-rings of course.  The new vesrah head gasket is way thicker than the cheap one.  And lucky me got too crazy pulling the valve train and popped the cylinder gasket.......more work!

I'll be copper coating both head and cylinder gaskets if they leak this time I am pulling the damn motor and swapping it for the spare 1977 400 motor I have sitting around.

All surface are true, I clean them with a scotch pad on the angle grinder.  going to acetone them just before I put the copper coated gaskets on.

[Muckinfuss]

That's the first I've heard of an MLS gasket leaking.

[Duanob]

Best advice: go with an OEM headgasket. If you can find one. And follow the manual on torque and sequence.

If you can find the head gasket?  And the price is ridiculous $65 just for the head gasket about $4 each for dowel & orifice gaskets = $16 , $23 for oem cylinder head gasket, & $5 for breather gasket.   Theyre pricey and I am cheap.....BUT that's why I am replacing it now!  The $50 complete gasket set form N/E fail big time!  I hope Versah is better which I've heard it is.  In the end I guess you get what you pay for.  I am sure OEM is the best option, I hope I don't kick myself in a few hundred miles.

Depends on what your time is worth! If you have the time to go back in yet again and replace a failing head gasket than saving a few bucks might be worth it for you. I would rather be out riding. I found a Honda OEM on EBAY for $56 delivered and my top end gasket kit already came with all other o-rings and paper gaskets. And YES on the copper spray.

[Wobbly]

That's the first I've heard of an MLS gasket leaking.

And it's the first time I ever had a head gasket failing me that quick. All other gaskets I used are Honda, by the way. I wanted to get the best there is. Oh well. Removing the engine gets better and faster every time.

[andrewk]

I've got one of these MLS gaskets leaking right now, too.  Started almost right away though, so I'm suspecting a dowel pin being too long since I had it decked.  Stock studs though, I feel like that was a mistake.

Thicker head gasket does not mean better.  Just increases the squish band.  I know you think that the OEM price sucks, but you'll be spending 65 if you end up buying 3 of the cheapies.  Make sure that thick gasket still lets the o-rings compress, that's one other potential issue.

Good luck!

[Muckinfuss]

We've been using both Cometec and Felpro MLS for a few years now in auto race engines and the installation isn't always as straight forward as many describe it.  I don't know anyone that installs them dry...many use copper spray just like a conventional gasket as described in above comments and many, including me, use a sealant called Hylomar Universal Blue.  The head and cylinders have to be decked and surfaced, almost to a mirror finish for the ones using superchargers.  Even a slight scratch in the surface can be the leak source.  Sorry to hear about your troubles since I know these aren't free.