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Discussion Starter #1
Anyone using a big bore kit on a Raptor660r I suggest you use SCE head gasket,this Cometic was on it maybe 1 month and I used the Bike about 4 times, and that's when I noticed the reservoir cap blowing off and coolant everywhere,upon my research I then asked on the forum for suggestions and Dezperado told me about SCE gaskets and the Stud kit which I bought both already but SCE still backordered till June 1st,with that said look at this picture,Brand Spanking New Gasket and look after 4 times I rode the Bike and not to hard either because I was braking in the Custom CP Carillo piston 102mm I bought for this bike....


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Some people will say Cometic gaskets are great, but I've seen and heard of so many that fail, I will not use them. Either factory Yamaha or SCE. I'll spend a little more money and not have to worry about a ruined ride.
 

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Discussion Starter #3
Some people will say Cometic gaskets are great, but I've seen and heard of so many that fail, I will not use them. Either factory Yamaha or SCE. I'll spend a little more money and not have to worry about a ruined ride.
Hey Dezperado Will this head gasket would work on my big bore.... SCE the main store told me 1 month ago they would've have it by the 5th of june,now they're telling me sorry but you have to wait until 7/13,another month....I told them refund my money you clowns.... anyway would this work? Is in stock but I need to know before making another purchase.....thanks


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Discussion Starter #4
Hey Dezperado Will this head gasket would work on my big bore.... SCE the main store told me 1 month ago they would've have it by the 5th of june,now they're telling me sorry but you have to wait until 7/13,another month....I told them refund my money you clowns.... anyway would this work? Is in stock but I need to know before making another purchase.....thanks


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Is not 105mm like it says up top....this is 102mm

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I may be getting older, but I refuse to grow up!
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Call Matt McCormick direct at ATV Parts Central, or Daniel at Cuervo Racing.
 

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Discussion Starter #7
Thanks

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Hey Dezperado,so after my build,changed my 01 transmission to a 05 transmission because 2nd gear is gone,as you may well know about this Raptors...anyway I swapped cases,installed a alba racing case saver because when my chain came off that's when 2nd gear broke....about this DANG 102mm Head gasket,so I went with the Cometic head gasket again since I had an extra kit here I used it then the next day my Copper gasket arrives in the mail.... but long story short I did used the stub kit and torque extra and still my reservoir cap is blowing out,I did a little hole on the ear to pull it off and tied it up with a strap tie so I wouldn't loose it like the last 2 they're expensive.... anyway cometic head gasket I wouldn't recommend anyone with a big bore kit...I took my time,I primed the engine made sure oil was going up to the camshaft....still Cometic head gasket Failed!!!! My Wife is gonna be pissed when she sees me tearing the Raptor apart again!!!! SHE SAID JUST BUY A NEW ONE ALREADY!!!!! SO I just may get a new 700.... I also have a 08 Honda TXR700XX that I'm repairing as well....PITA Too!!!!!

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Did you check the head for warpage? IDK about the 660, but it's a common problem on the 700.
 

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Discussion Starter #9
Did you check the head for warpage? IDK about the 660, but it's a common problem on the 700.
Yes I did checked the head for warpage and its good!!! I bought it of Yamaha Atv mechanic he also checked it before selling it to me,-–I will try the copper head gasket I guess next if that don'tgo well...I will try and find an SCE head gasket again....also I'm gonna have my Yamaha cylinder bore to 102mm.

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Cometic gaskets isn't your problem. I haven't been on the forum in years but stopped by today and saw this thread. This is only for information purpose so others won't run with the idea that a gasket brand can cause failure. I've built a lot of 660 motors (a few over 90 horse power) and I've used Cometic gaskets on all of them. You really need to inspect everything when you build. deck surface, head surface, measure squish and then determine the thickness gasket you need; head and base. Head and base gaskets can be made in any thickness Copper or Multilayer and delivered to your door in less than 2 weeks. I order gaskets from Cometic all the time. They have great customer service and they always get me set up fast.
 

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I'll add piston deck height to the list
 
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