XR400 head gasket?

[Dune Surfer]

I read the Mickey Dunlop post here and he said installing a xr400 head gasket would boost power with a stock piston. Has anybody tried this? Is it worth it? Is it hard to get the head off? How much harder would it be to install a drop in cam at the same time? And what cam, I'm looking for overall power, Riding mostly BIG dunes at Glamis. XR 400, hot cams WB????. It's a 02 ex so I am a little leary of losing reliability. Come on pro"s what do you think??

[Leo]

I wouldn't bother ripping the whole bike apart just to put the XR gasket in (your probably talking a .2 boost in compression MAX)..

When I put my stock bore hi-comp piston in I used the XR gasket just to get close to the rated compression of the piston.. It was a JE piston and the 10.5:1 was in the XR motor.

Leo

[Dune Surfer]

How much do you think it would cost me to get set up with a piston and cam installed? and is it worth the $$$

[VegasEx'r]

Originally posted by surfski
How much do you think it would cost me to get set up with a piston and cam installed? and is it worth the $$$

Are you going to do the work yourself? If so, you can get all that for about 350ish (including the bore). Call Terry at Marcum's, he can set you up. But if you want the xr gasket, you'll have to get that from a Honda dealer. As far as a cam, don't get the xr cam. It is a good cam, but not for the dunes. I have been very happy with my Hot Cam stage 2. It is much better for duning. Bought it from C&D Racing for 136 to my door. While you have the top end apart, you might want to look into a port & polish or ceramic coating the piston & exhaust ports.

[Big - D Racing]

How does a gasket boost compression. This is the first I've heard of this. Any details would be appreciated.

[mysticfalcon]

the xr head gasket is thinner than teh ex head gasket which is like lowering the deck height.

[Big - D Racing]

is it just as good and long lasting, though? If it's all good, I just might have to get me one.

[Teufel]

Originally posted by Big - D Racing
is it just as good and long lasting, though? If it's all good, I just might have to get me one.


It's not a dramatic change and won't effect reliability

[VegasEx'r]

Yeah you won't feel a difference between the xr & cometic gaskets. Be careful about taking the head off too many times, the studs will weaken which can cause head gasket failures. The rule-of-thumb I have heard from a couple of people is that it's okay to take the head off once, but if you do it again, you should replace the head studs. I have had my head off twice and in the past month I have noticed that oil leaks from the bottom of the head, so I guess I'll replace my studs & gasket soon (as soon as I have the cash for a port & polish)

[Leo]

the XR gasket is top-notch, a multi-layer steel headgasket just like the OEM EX gasket, just it's a hair thinner...

I used a honda gasket set when I did my EX, but I used a cometic base gasket because it was thinner (had a cometic kit laying around).. now I have a leak at the base of the cylinder (grr..!)

I've recently decided that a wild cam / 12:1ish piston / FCR carb need to be installed in my bike :D so I plan on replacing the cometic POS with the factory gasket while I've got 'er all apart..

The only decision I have left is 416 or 440 ;)

Leo

[forum]

I'm pretty sure the newer 400ex's have XR 400 cams in them. I think 02 and on. Reading posts on this site sometimes makes me wonder if this is right. But it was confirmed when my buddy ordered a stock 400ex cam from the local shop and when it came in. It had a decompression thingy and we removed it before putting it in. (well the shop guys removed it saying "you don't need this")
ALso I remember reading an isue of dirtwheels ware they stated this xr cam isue is true.

i feel Sorry for those guys an gals putting xr cams in there new ex's. but you have to laugh when they claim horse power gains

[VegasEx'r]

Originally posted by forum
I'm pretty sure the newer 400ex's have XR 400 cams in them. I think 02 and on. Reading posts on this site sometimes makes me wonder if this is right. But it was confirmed when my buddy ordered a stock 400ex cam from the local shop and when it came in. It had a decompression thingy and we removed it before putting it in. (well the shop guys removed it saying "you don't need this")
ALso I remember reading an isue of dirtwheels ware they stated this xr cam isue is true.

i feel Sorry for those guys an gals putting xr cams in there new ex's. but you have to laugh when they claim horse power gains

How does having a decompression release prove that the xr & ex cams are the same? I have both laying around, both with decompression assys., and both with different lobe specs. Did you measure both cams to verify they are the same, or do you just figure they are since they both have decompression on them?

I might be coming across as rude, and that's not my intent, but this is the first time I have heard anything like this, & I just find it hard to believe that Honda would retune the detuned 400cc engine.

[Leo]

Originally posted by forum
I'm pretty sure the newer 400ex's have XR 400 cams in them. I think 02 and on. Reading posts on this site sometimes makes me wonder if this is right. But it was confirmed when my buddy ordered a stock 400ex cam from the local shop and when it came in. It had a decompression thingy and we removed it before putting it in. (well the shop guys removed it saying "you don't need this")
ALso I remember reading an isue of dirtwheels ware they stated this xr cam isue is true.

i feel Sorry for those guys an gals putting xr cams in there new ex's. but you have to laugh when they claim horse power gains

the stock 400EX camshafts have always had the decompression assembly, but they are not the same as the XR400 camshaft.. (the milder camshaft is part of the reason the EX motor is considered to be de-tuned from the XR version)

the dealer actually went through the trouble of removing the decompression release it before installing the camshaft..?

that makes me wonder..

1- what was the dealer thinking?
2- I hope he removed the locating pin and spring also ;)
2- why pay dealer prices for a stock camshaft? you can pick up an XR camshaft for ~$120 mailorder or an aftermarket for ~$150-$175.. (as opposed to what about ~$200 delear price for an OEM chamshaft?)

I'm afraid someone has you seriously mis-informed..

Leo

[MIKE400EX]

Leo, if you ride in the wood much >>> go with the 440 (435), ~11:1, and get a piston that is close to the stock 400 weight. Then you'll be happy!