[XR400 head gasket........] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

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XR400 head gasket........
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Posted by: trx400EXtreme

good mod? i here that because it is thinner it adds more compression. how much more are we talking here? do you have to trim it at all?

Posted by: the Z Man

You have to be careful, I had a high dome piston that hit the valves from the difference, Z.

Posted by: trx400EXtreme

do you think there would still be clearence issues with the stock piston?

Posted by: hornetgod13

I have one installed on my 416EX and it has a 11:1 High Compression Piston and there is no clearance issues with the piston to valves. It's also large enough to accommodate an 87mm or smaller cylinder set up.
I have read the same that you have about the added compression but, I'm not sure how much. It's a 1/16th to 1/8th inch thinner than the stock head gasket I pulled off.

Posted by: trx400EXtreme

thanks. so just a guess. if stock is 10:1 comp., what might this bring it up to? 10.2-10.3:1?

Posted by: Hondamaster5505

quote:
Originally posted by trx400EXtreme
thanks. so just a guess. if stock is 10:1 comp., what might this bring it up to? 10.2-10.3:1?

Stock is like 9:1 or 9:5

so it might make it 10.5:1 ??

Posted by: trx400EXtreme

my bad, i did a little research and yea stock is more like 9.4:1 or something.

Posted by: Pipeless416

wiseco 11.1:1 pistons are actually about 10.8:1, however with an xr400 gasket, i've heard they become true 11.1:1 compression. im guessing they add about .3 to your compression ratio.

Posted by: drew416ex

you wont have a problem with valves hitting. I have a stroker crank, 11:1 piston and cam and I have no base gasket and mine dont come close to hitting.

Posted by: drew416ex

quote:
Originally posted by hornetgod13
I have one installed on my 416EX and it has a 11:1 High Compression Piston and there is no clearance issues with the piston to valves. It's also large enough to accommodate an 87mm or smaller cylinder set up.
I have read the same that you have about the added compression but, I'm not sure how much. It's a 1/16th to 1/8th inch thinner than the stock head gasket I pulled off.

Not trying to start anything but its not 1/16 - 1/8th inch thinner. The gasket itself might be 1/32 total if its that thick. The xr gasket is around .010"-.020" thinner.

Posted by: hornetgod13

quote:
Originally posted by drew416ex
Not trying to start anything but its not 1/16 - 1/8th inch thinner. The gasket itself might be 1/32 total if its that thick. The xr gasket is around .010"-.020" thinner.

1/32 to 1/16 as compared to the stock replacement gasket, I can see that. I didn't measure it. I wish I had now.

Posted by: Maxx Racer

.010 raises .3-.4 a compression point in a car. Give me gasket thickness stroke etc I'll probaly be able to find out what it will make it.