Blown Head Gasket

[Fast350ex]

I blew a head gasket in my 400 at the track, and I rode with it like that. I was wondering how long you can ride with it like that before it starts to warp where the 2 piece cylinder meets?
I've been riding like that for a while, will it cause serious damage or can it be fixed?I could just have the cylinder lapped off to get rid of the warpage.
Anyone know the torque specs on the head bolts so I can replace it?

Thanks.

[Fast350ex]

?????? BUMP ?????????

[cals400ex]

the specs are 33 ft-lbs. if it blew, i have a feeling either your mating surfaces are warped or you pulled head studs.

[Buffalo400]

aftermarket head stud?

[UglyMotha™]

if you keep running you are goin to erode the two mating surfaces and both will have to be resurfaced

[BLEEDRED]

My headgasket slowly blew out over the course of recreational season. It blew on the timing chain side because there were some damaged bolts and the head/jug was not held secure. It warped the cylinder and I had to have .010" decked off. I recommend fixing it ASAP. Good luck. Might want to go with HD head studs too.

[Fast350ex]

Yeah, I have stock head studs. What all has to be done to replace the head gasket? I pretty much know how to take the head and stuff off and the timing and all that. But will I need a special tool to squeeze the piston/ rings back into the head?
How can you tell if it has to be decked or not? It's probably not visible.

Please help!!

[Fast350ex]

BUMP

[BLEEDRED]

But will I need a special tool to squeeze the piston/ rings back into the head?

Dude, the piston sits in the jug below the head, shouldn't have to mess with it to replace the head gasket. But if you yank the jug you might as well replace the rings and have the cylinder honed. You can load the rings on the piston by hand, just be careful. Make sure to check your end gap on your rings and install them the right way (letter/mark pointing up). You can load the piston into the jug by hand also too. It's easier to do on the bench and then just get somebody to help you hold the jug while you put the wrist pin back in through the connecting rod. Also make sure you relpace the cir clips with new ones if you are going to pull the piston off the rod.

Why are you replacing the head gasket in the first place? I knew mine had to be decked because the jug was warped and was blowing oil out the head gasket. You will have to check to make everything is true, I had a machine shop do that for me.

[Fast350ex]

I have the same problem!
Oil is seaping out of the head gasket, and I rode it like that. That is my concern.

[Warnerade]

when you replace it, get OEM gaskets...they are the best. After you install that...tighten the bolts down to 33 lb tourque...put the engine together and just plug it all in and set your gas tank on top. start it up...let your engine warm up...turn it off, and take the tank back off. Take your valve cover back off and re-tourque the head bolts back down. This will basicaly insure that your head seats correctly and wont blow another gasket.

[Fast350ex]

When you take the head off, is the warpage visible? Or is there some sort of way you can tell, like putting it on a perfectly flat surface; like a glass?
Which part will need to be decked? The head or the jug? , or both?
If it's both; I'll probly let the pros. handle that.

thanks.

[Warnerade]

you may be able to tell on a glass surface...but even stuff such as glass is not perfectly flat. My suggestion is take it to a machine shop....ask if they can put your head on a graphite surface plate...and then you could just poke feeler gauges under it to see if its warped...

[Fast350ex]

If I take it to the dealer, will they be able to tell?
Do they have the stuff to deck it if needed?
If I blow another one, and I don't ride it; just replace the gasket, it shouldn't be warped right? I can just take the head off and replace the gasket?
I got a stock gasket and took the rivets out so I could use a thinner piece for more compression. Which piece should I use?
Will it blow easier?
What are the signs of it blowing besides the oil leaking from the gaket?

Please help.

[BLEEDRED]

I got a stock gasket and took the rivets out so I could use a thinner piece for more compression.

Approach with caution. This can be done and with success, but you will want to spray the gasket with high temp. paint on both sides to help it seal. I would think you would want to find out why you blowed up the head gasket in the first place before you go ahead with only one layer of gasket. It's up to you, but one layer of head gasket does not make be feel warm and fuzzy inside.

[cals400ex]

we have used the one layer head gasket before. we painted them. out of 3 tries, we only had one that sealed perfectly and and stayed that way. we now just use no base gasket and a thin cosmetic head gasket. we haven't had a problem with this yet and we have done it on 4 bikes as of now.

[BLEEDRED]

I agree with Cal, that's how i set up my bike, with no base gasket and a .027" Cometic head gasket. If you just want a little compressoin boost you can always use the XR400 gaskets. I hear they are thinner than stock 400EX gaskets. What you really need to do is figure out why you started blowing oil in the first place. If you are going to pull the jug and cylinder you might as well add a high comression stock bore piston. IDK, it's up to you. Good luck.

[Fast350ex]

Stock bore piston!!

I have a 416 Wiseco 12:1 piston
SPARKS- x-6, cam, cam chain, valve spring kit, rod, & full race port work. 39mm Keihin fcr carb. and K&N.

I never had a problem with head gaskets before now!
I know it's the head gasket because it seeps oil between the head and the jug. I noticed it at the track, but I don't know how long I ran it like that. I definately didn't notice any loss of compression! And it runs fine. I just don't want to screw it up more than it might be.

Thanks.

[Fast350ex]

Anyone want to say something about this? :confused: