Big bore head gasket?

[Cannonball08]

I just bought another 400ex, fully loaded The only thing that is stock is the frame and its been powder coated! I am really excited about racing this quad. My question is, this bike has a IMS 440 kit bored .40 over and it keeps blowing head gaskets. Im guessing there is to much compression there so it keeps blowing. Do you guys have any recommendations on who makes a head gasket that won't blow?

[quadman21]

How many have you blown? Does your head nuts hold the torque or are they loose when you take the head off?

[Silverfox@C&DRacing]

I would check what quadman21 said and then use a cometic steel flex head gasket :)

[quadman21]

The reason I ask is because when I first had my 440 kit inatalled I had a shop do the work but my studs stripped. I had a lot of trouble blowing head gaskets. I eventually bought a new OEM cylinder and new studs. I had a local speed shop install my sleeve and I put it together myself. I also put the new studs in the new cylinder myself and have had no trouble for about six months or more. I just blew my head gasket last week after I got home from a race, My cylinder nuts were not at 33 FT-LBS. So I installed a new gasket and after I race this weekend I'm gonna go back and re-torque. I also use the steel cometic.

[AndrewRRR]

If I were you I'd just get a new gasket and make sure your head studs are torqued to spec before each race. If you keep blowing them I'd say the gasket isn't your problem. You might need your head milled or cylinder decked, they may be warped.
When I was considering going with a really strong metal gasket for my built eclipse, someone brought up an interesting point: "Would you rather blow a $50 head gasket, or break $600 rods, or a $800 crank?". Sometimes it's a good idea to have the weakest link also the cheapest link!
I'd just make sure your bolts are torqued and see what happens. If it still blows, check for other problems. Also, what is your compression? Detonation is more likely to blow gaskets than compression. What gas are you using?

[quadman21]

AndrewRRR, I know this is cannonball08's thread but this questionmy help him also. I have never decked my clyinder. By not doing that I have read many threads stating that with the weisco flat top 89mm 11:1 piston your not at a true 11:1. Also, I stopped running race fuel because of the price and I had read in another thread that you can go up to 11:1 without burning race fuel.

[pairanutz]

On my 440 i kept blowing gaskets because my bolts wouldnt hold torque -after i had all my head studs hela coiled then lock tightened my problems went away till my rod gave out

[quadman21]

Well, back to the point of canonball08's post...What is the "magical" fix? Or what are the tricks to keeping them from blowing? Do you just go back and re-torque? My 440 is a mild 440. I have a mild port job with an XR cam and the cylinder is not decked. Nothing crazy. As I posted earlier my 440 was running great for a long time. It even had two races on her. Then out of nowhere it blew the gasket just ridding at the house. What am I doing wrong and what should I (we) do to keep them from blowing again?

[F-16Guy]

Most guys with 440 kits will probably tell you to invest in an oversized stud kit. The larger diameter studs hold in the aluminum threads much better. Have the machinist that installs them chase the threads in the cylinder with an end tap, you'll get a few more threads out of it. Also, use the metal head gasket, not fibre.

[oregonrider89]

Like "pairanutz" said, get your cylinder studs heli-coiled and have your head and clyinder milled. This should solve your problems. One thing to remember, let your quad get good and warm before you rail on it.

I blew 2 head gaskets on my 440 so I had LRD do the heli-coil and mill work. I used a cometic head gasket from C&D Racing (our site sponcer) and I haven't had any trouble yet.

oregonrider89

[AndrewRRR]

Well if your studs/nuts keep backing out, address that problem first and it will probably solve your headgasket issues like mentioned above. Trying stronger headgaskets while your head studs keep backing out is like putting a band-aid on a bullet wound.
I would do a compression test to see if you need to run more than pump gas. A company can claim whatever they want for compression (13:1, etc) but it really all comes down to what psi you are getting on your bike. I think around 165-170psi is where you start needing race gas. Someone correct me if I'm wrong.

[RAPTORAZ]

Send your jug to Sparks Racing and have them install their larger head stud kit. It only costs $25.00 for the kit and install and your head gasket blowing days will be over. My buddy's 440 has been trouble free since he did that.

[quadman21]

RAPTORAZ, do you have the info on Sparks racing? This way I can have it on hand if I need to go that route in the future. Thanks

[Steven]

This is what I did and so far no blown head gaskets with 11.5:1 compression on my 440.

I bought new OEM cylinder studs which were inexpensive... about $5 ea. Then I had my machinest retap the cylinder stud holes with a bottom tap which had the head filed off. He got another three to four threads out of each hole before he hit bottom for more holding power. I run the cometic three piece steel .025 head gasket and its still holding.

The guys are right though... it the surfaces aren't flat than it will never seal. And stay awar from the composite gaskets because they will need to be retorqued after one heat cycle.

[RAPTORAZ]

Originally posted by quadman21
RAPTORAZ, do you have the info on Sparks racing? This way I can have it on hand if I need to go that route in the future. Thanks

www.sparksracing.com