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I have a blown head gasket on my YFZ450 with the Athena 480 Kit. After searching around, some people are saying this is common. I also heard that the cometic head gasket is a better solution. I am just looking for some more opinions on the cometic head gasket vs. replacing it with another bad Athena gasket. Maybe Athena made some improvements? Any information would be helpful.

Matt 8|
 

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Putting a cometic on my 480. don't reuse the head bolts unless you have ARP Head studs. Getting the cylinder o-ringed is an option. Sredrum and a few others do that.

I'll see how the cometic on the 480 with a 13.5:1 holds up soon.
 

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Well, I blew the head gasket right after break-in. New cometic head gasket, new studs, machined flat head, and cylinder checked for flatness.

Not even an hour on the build... Was going to get the cylinder o-ringed but I called KMS Performance about some info on the ARP studs. He said not to o-ring the cylinder. He has a process that he uses that doesn't blow head gaskets, even with turbo and nitrous set ups. For $45 to do the work on the cylinder, I'm all in. Plus, I am going with the ARP studs and a new Cometic MLS Head Gasket. Should seal for sure!

Call Kelly at KMS Performance if you want more info. He was more than helpful!
 

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What does his process involve? That way we don't all have to call him up.

My pump gas Athena 480 is still pushing coolant, I'm on my 3rd head gasket. This last time I only used 50/50 110 race gas & 92 and all surfaces were machined flat. I'm starting to think the Vortex uses to much timing for a 480 Big Bore. I wish I could get the detailed timing info from Richard @ Vortex, but he won't disclose any info on his maps.
 

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What does his process involve? That way we don't all have to call him up.

My pump gas Athena 480 is still pushing coolant, I'm on my 3rd head gasket. This last time I only used 50/50 110 race gas & 92 and all surfaces were machined flat. I'm starting to think the Vortex uses to much timing for a 480 Big Bore. I wish I could get the detailed timing info from Richard @ Vortex, but he won't disclose any info on his maps.
I'm not sure on the details honestly. I didn't want to spout out wrong information. He did tell me exactly what he was doing, i just didn't make a lot of sense of it. Maybe someone else can call and ask about it. Or i can wait till i get my cylinder back and show you. I'm more of a hands-on guy... Sorry... He learned this process from one of the guys at Cometic, Kevin i believe. He actually asked me if i had a lathe so i could do it myself, but i don't have access to one. From what i remember, he said to machine .003" off the top and stop at the coolant jackets. If he meant to go from the inside-out or the outside-in, i do not know. Then to use ARP studs, and a new Cometic MLS gasket. Then torque to 40 foot pounds. He said he never had a problem since using this method.

Again. I don't know if this is exactly what he described to me, but i will try it. To get this done is $45 and to get the cylinder O-ringed is $100 somewhere else.

This method was completely new to me but he had engines with turbo-nitrous setups running 100+ without blowing head gaskets. Worth a try i say.
 

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here we go. The top of the cylinder was machined all the way past the water jackets up to about 1 mm of the wall of the cylinder.

I got my quad together, but i can't get it to start. I'll let you guys know how it holds up once i get it going.
 

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Looks good, kind of like a built in fire ring. Is it raised up near the cylinder wall about .003"?

How much did they take off the cylinder, will that change your squish?
 

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I did not check how much was taken off myself. I was in a hurry to get it together for the races. He told me it was .003". I could barely feel it with my finger nail. My phone did do a pretty good job a showing the difference in height. Being .003" difference, i imagine i would not have to reset the squish. I was at .039". So even if it did change to .036", I am not going to worry about it. Now if you are pushing the squish boundaries, it would be something to look into. I don't think it would change the squish though.

On a side note, he had to make a special bracket to put the Athena cylinder on the lathe. He said it was just slightly different than the OEM cylinder. But he got it done very quickly!
 

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Just an update on this.

I have had multiple rides on this cylinder after sending it to KMS Performance. It has yet to blow the head gasket. I'm pretty excited about this. I was starting to regret getting a 480 kit and bumping the compression. If anyone is having issues with blowing head gaskets, i definitely recommend Sending your cylinder to KMS and getting the ARP Head studs from them as well.
 

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If the )-ring/ Fire Ring is done correctly it will hold and not fail. However some use the wrong kind of wire, or they leave it sticking up to far thus creating more problems.

On my current drag bike the motor is a 98mm bore and +6mm short rod falicon crank. This makes a 513cc motor, and NOT a long rod, so piston speed is faster then a long rod set up. I am using a 98mm JSR cylinder that is NOT o-ringed/ fire ringed and I use a 98mm Cometic gasket. It currently uses a Venom 14.25 piston. I am even using OEM head bolts.

I am a firm believer in Sredrums work and how he installs the cylinder o-rings.

I also know you do not need a o-ring, when you use some common applied knowledge when assembling the motor.

I will add that work done to your cylinder looks top notch work, and should hold just fine. The only issue I can see is you can not longer surface the cylinder flat should you ever need to.
 

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If the )-ring/ Fire Ring is done correctly it will hold and not fail. However some use the wrong kind of wire, or they leave it sticking up to far thus creating more problems.

On my current drag bike the motor is a 98mm bore and +6mm short rod falicon crank. This makes a 513cc motor, and NOT a long rod, so piston speed is faster then a long rod set up. I am using a 98mm JSR cylinder that is NOT o-ringed/ fire ringed and I use a 98mm Cometic gasket. It currently uses a Venom 14.25 piston. I am even using OEM head bolts.

I am a firm believer in Sredrums work and how he installs the cylinder o-rings.

I also know you do not need a o-ring, when you use some common applied knowledge when assembling the motor.

I will add that work done to your cylinder looks top notch work, and should hold just fine. The only issue I can see is you can not longer surface the cylinder flat should you ever need to.
Yeah, i wouldn't be able to go back after having the work done to the cyinder, but i don't see a need to. Kelly of KMS Perormance got this method from one of the guys at Cometic Gaskets when he was having issues with one of the boosted builds he was doing. He had tried everything and something this simple worked the best. It holds up after multiple builds, and it was extremely cheap!

Sredrum does great work, turn around is just a little long and he is harder to get a hold of. I guess it helps to know him personally. Both guys have the knowledge to get builds done the right way. I would recommend both.
 

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Ya it looks like quality work for sure. Just do your best not to over the heat motor. Make sure to install a temp gauge on the motor side of the radiator to monitor the temps coming out of the motor. Once the cylinder over heats it can warp. If it does warp that's when the re-surfacing it will become an issue.
 
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