1 layer head gasket??

[slosh13]

Has any one heard of taking a stock 400ex head gasket and seperating the layers and just using one.:huh I heard this from an engine builder to boost up compression. How reliable would that be?

[ghak99]

It would up the compression some, not sure how much, But I would think it would not provide as good as a seal as using it as it was designed.

Just my 2 cents

[Colby@C&DRacing]

It will raise the compression but has more of a chance to blow out. Not to say it will but it can easier than a three layer gasket

[Dunlap]

If you take the base gasket out and only use 1 part of you head gasket it will be the way Honda should have made it. Be sure to paint it with heat temp. paint for a better seal.

[slosh13]

maybe what im not understanding is why would you use only one part of the headgasket instead of all three parts? What type of advantage are you receiving with only using 1 part? Could it potentially be bad for you motor?

[Colby@C&DRacing]

It will not hurt anything. It will just raise the compression

[skemp]

Like Colby said, it just raises the compression a little. I have been doing this on my sleds for years. It doesn't give as good of a seal, however, so do as Mickey said and hit it with some paint. I use copper seal on mine and it works fine. You can use RTV instead of a base gasket EDIT: Oops, got mixed up; no RTV on head gasket.
Doing this will result in a noticeable difference in power.

[cals400ex]

i don't see how the paint helps it seal?? it is just a layer to makes it adhere better? is rtv ok?? i have been told not to use that, but i honestly don't know. also, how much would that raise the compression if you only used 1 out of the 3 pieces?

maybe if u had 11:1 it would raise it to 11.2:1 or 11.3:1...which really isnt that much of a difference...personally i would not recommend it

[UglyMotha™]

Originally posted by cals400ex
i don't see how the paint helps it seal?? it is just a layer to makes it adhere better? is rtv ok?? i have been told not to use that, but i honestly don't know. also, how much would that raise the compression if you only used 1 out of the 3 pieces?



the paint just adds in that extra squash layer

[Dunlap]

Originally posted by XxHonda_RacerxX
maybe if u had 11:1 it would raise it to 11.2:1 or 11.3:1...which really isnt that much of a difference...personally i would not recommend it

Thats why you take the base gasket off. And the paint is to seal ti just like the stocker,DO NOT put any kind of rubber sealer on the head gasket.

Originally posted by Mickey Dunlap
Thats why you take the base gasket off. And the paint is to seal ti just like the stocker,DO NOT put any kind of rubber sealer on the head gasket.

ya my friend runs no base gasket at all

[400rednEX]

what exactly do you paint it with?

[nacs400ex]

Originally posted by 400rednEX
what exactly do you paint it with?

Paint:o

[JOEX]

Originally posted by nacs400ex
Paint:o
What color?:blah:

[UglyMotha™]

Originally posted by 400rednEX
what exactly do you paint it with?




Be sure to paint it with heat temp. paint for a better seal. ;)

[400rednEX]

is that a brand name or just high temp paint in general?

[Dunlap]

Pink works for me:D

Or krylon Bar-B-Q / stove black

[400rednEX]

thanks for the info guys. so is no base gasket and 1 layer of the head gasket a noticable power increase over the stock gaskets with the stock piston?

[2004TRX450R]

It will raise the compression and give you more torque BUT it will also mess up your cam timeing. With the cam being closer to the crank it will throw it off by just a little. If you have a way to degree the cam then no sweat. I wouldn't use RTV either. I'd use something like Hondabond or Yamabond. It won't deteriorate with contact with patrolium based oils. I wouldn't just leave gaskets out either. You are just asking for trouble when doing this. If you want more compression just do it right and get a new piston. That is my professional opinon.

[UglyMotha™]

hhmmmmm mickey dunlap's professional oppinion or 2004trx450r's professional oppinion.......choices, choices, choices :confused:







oooooooooooh i love it :blah:

[kenny]

ive asked about a copper 1 piece head gasket got no replys or input on it.ive been told the head gasket shim type 3 layer gasket is designed to allow for heat expansion and contraction. i just blew my 3 piece gasket. between the shims.any body know about the guy on e bay with the copper gaskets that come in 5 different thicknesses.

[Dunlap]

Read my post on "tips on bore jobs & resleeving and maybe that will give you the answer. With the tips I give you can run any kind you want but the "Cometic steal " is the best and IF everything else is right you will not have a problem.

[cals400ex]

how much will this affect timing?? couldn't you adjust this by the way you line up top dead center on the flywheel??

[Dunlap]

Most cams that peoplehave are very mild so its good that you retard your cams and its only 2 or 3 degrees. Most cam chains are streched more than that so put a new cam chain in it if you are worried about it. Also there are not to many people building full race motors on here anyway so 2 or 3 degees this way or that is no big deal you are going to gain more by the added comp. and the better flame travel.

[2004TRX450R]

you would have to have an adjustable cam sprocket. The only way you could adjust anything is by moveing it a whole tooth on the sprocket in wich it would be WAY off so you can't do that. If you chain is stretched much and you do this it is going to be even farther off. Another good point was brought up. Most of the people on this board aren't building race engines. So you want more reliability. On race engines when they do stuff like remove gaskets, split others down and stuff like that they aren't worried about them sealing for extended periods of time. All they are concered with is them lasting for a couple of races until the engine is freshened up again. So it doesn't have to be nearly as reliable as someone that just wants a little more power in their trail/dune bike. So by doing stuff like this sure it will work and go together and run but for how long. If you want to keep all the reliability of the engine then do the performance upgrades properly and don't try to bandaid it together to try to get that extra .2 or .3hp out of it.

[Dunlap]

2004TRX450R,

It's OK to have different opinions but when I state things on here it's because I have tested and proven it and my reputation as a professional engine builder and business owner I have to make sure that the people can use this information without any problems. Therefore, I would not tell somebody to get rid of the base gasket or to use paint only on the head gasket unless I was 100% sure that there would be no problems. A couple of things I disagree about with you is using Honda Bond or Yama Bond on the head surface. It was never designed to withstand the high temperatures that close to the combustion chamber. That's why we use high temp paint as Honda does that will withstand heat up to 1,200 to 1,400 degrees. The thing about this modification is that it's not unreliable. In fact, it is free horse power that anyone can do and it actually makes the engine run cooler with the proper quench area around the outside of the piston along with a better flame travel which gives you better performance. Having the proper quench area around the outside of the piston keeps the heat away from the rings and extends the life of your engine. The kind of engines I build are not full race but are designed to give good hp gains and keep the reliability and longevity as close to stock as possible. On the base gasket, I have stated in other posts that I use Honda's high temp silicone seal which withstands high pressure in case there are any low spots on the cylinder surface or the cases. I have never had a base gasket leak with this and I would recommend it highly. Just make sure the gasket surfaces are cleaned with acetone before assembling.

[UglyMotha™]

hmmmm choices................ :eek:

[skemp]

If it matters to anyone, I have been running my quad like this for almost 2 years now, and it hasn't leaked in those two years. What I thought was a blown head gasket turned out to be a leaky valve seat area. 1 layer head gasket with plain old black BBQ paint, and RTV instead of the base gasket. It does run cooler this way due to the improved quench area in the combustion chamber (about 17-18 degrees cooler to be exact). After going from a Honda base and head gasket to this setup, there was a surprising difference in power. This brings the EX motor closer to what the setup was on XR's.

[400rednEX]

it sounds like a good winter project, thanks.

[wilkin250r]

So, 1 layer head gasket with pink paint, and Honda high-temp RTV instead of a base gasket.

Are these modifications to the stock motor, or in addition to other modifications? Would you run into a problem with the quench area with a high-compression piston?

[skemp]

This is on my 416 with a high comp. piston. And you don't have to use pink paint wilkin, most pastels work lovely ;)

If you wish to learn some more about quench/squish, check this out (http://www.theoldone.com/archive/quench-area.htm) . Some good reading if nothing else. The theory with quench is that with a perfectly designed head/cylinder combination, you will achieve maximum compression with minimum octane. The perfect naturally aspirated 4 stroke would be able to run like 14:1 compression on 87 octane gasoline, given the quench was perfect. There is some good reading out there on this topic. Look around and you will learn some valuable info about a topic that isn't commonly discussed.

how exactly do u set this up...i want in on this...sounds pretty damn nice...what exactly do i need to do and how do i go about doing it??:confused: ...this would be a great thread for the tech articles or faq

[skemp]

Take the gasket, and seperate the three layers by grinding the brass rivets apart. You are left with 3 layers. You just use one and shoot the gasket with some BBQ stove/high temp paint. Take out the base gasket and clean up the mating surfaces with an MEK or Acetone solution. Put a bead of RTV silicone around the base and bolt it down. Put the painted gasket back on and torque down the head to spec, and hope you did it right so it doesn't leak. Pretty easy, it is mostly self explanatory. :)

ok thx for that :D ...havent been in this thread so i had no idea how to do this :o

[2004TRX450R]

I did not mean to use yamabond or hondabond on the head gasket. I meant for use with or wtihout a base gasket.

[slosh13]

Ive heard from an engine builder that you can go all the way up to a 14.5 :1 compression ratio with this setup on a 400ex:eek2: :huh

[cals400ex]

Originally posted by slosh13
Ive heard from an engine builder that you can go all the way up to a 14.5 :1 compression ratio with this setup on a 400ex:eek2: :huh

is that on 87 octane??:D

i assume you need to use a thin bead of rtv sealant on the base so no excess gets into the engine??

[JOEX]

Originally posted by cals400ex
is that on 87 octane??:D

i assume you need to use a thin bead of rtv sealant on the base so no excess gets into the engine??
I was wondering about that myself.

I watched a guy rebuild a Muncie 4-speed tranny for me many years ago, instead of puttinf a 'bead' aound the surface, he squeezed some out and spread it out with his fingers to make a thin layer around the entire surface.

I don't know if this would work for this application though.

Joe

[skemp]

The idea is to get a thin enough bead of silicone to provide an adequate seal without excess. You can spread it on with your finger, but basically just use good judgement. A good deal of it will compress out the sides of the base when you bolt the cylinder down, so apply it sparingly.

[MIKE400EX]

Use the RTV sealer at the bottom of the jug very sparingly. If it gets into the top-end oil passage and restricts or blocks the oil flow to the valvetrain that little bit of added compression won't do much good. Fingers work very well for spreading it out thinly (as JOEX & Skemp pointed out).

[wilkin250r]

I have done research into the quench/squish band, and I'll share that with you. Mickey Dunlap can go further into detail, or correct any errors in my thoery...

The squish area is the area between the piston and head that is near the cylinder wall. It is a ring all the way around the cylinder.
http://www.aircooled-rd.com/images/rdheat1.jpg


We all know that as you compress gasses, they heat up. Too much heat, and they detonate. This is why high compression motors need higher octane, because the higher octane can resist higher tempuratures and pressures.

So, the basic theory as far as I can tell (and Mickey Dunlap can correct me or expand into further detail) is that this area of the head is COOLER than the gasses that are being compressed. By properly setting up the squish band, you can actually cool the compressing fuel/air mixture.

This is absolutly magic! If pressure equals heat, and heat equals detonation, but NOW you can reduce heat, then you can go even higher in pressure!!! More pressure equals more power! By cooling the fuel/air mixture, you can go higher in compression before detonation. This is how you can run a 14:1 compression using a standard 87 octane fuel!

Perhaps a true engine builder could expand on this a little further?

[Dunlap]

Wilkin250r

Your doing a good job exsplaining the basics, but that 14:1 on 87 would only work in a perfect world. I reality 12:1 with 92 or 93 is about as good as it gets.

[wilkin250r]

Originally posted by Mickey Dunlap
Wilkin250r

Your doing a good job exsplaining the basics, but that 14:1 on 87 would only work in a perfect world. I reality 12:1 with 92 or 93 is about as good as it gets.

Ok, I'll buy that. I was just using the 14:1 example because somebody else had mentioned it. I know the basic theory, but I have no idea of the actual limits that can be reached.

[skemp]

Lab wrenchers have been able to make a small thumper run consistently on 87 octane with close to a 14:1 compression ratio. This of course took some very precise measuring and machining, as well as some extensive tuning on the ignition system which was connected to a computer. In the real world, it only gets as good as what Mickey said. There are too many variables that can throw the potential off, like fuel quality/contaminants, individual head design, and a given motor's unique running characteristics, not to mention a bunch of others.
It's all fun stuff to talk about, but what really matters is applying that "stuff" to a motor and making it run. :)

[cals400ex]

so about how much will the compression change from using one head gasket instead of the 3 layered one and removeing the base gasket?? i assume only 2 tenths or so?? if you only remove one or the other, which would be more beneficial?? will this change in compression be noticable by driving the bike??

[toby400ex]

I just ordered a Je 416 kit from marcums. I guess its an 11:1 piston but since they dont feel the need to make a true 400ex 11:1 piston it is 10.8:1, will removing the base gasket and using one layer of the head gasket make it 11:1? And am I supposed to use the paint on both the gaskets? Ive read all of this but, alot of things are said.:huh

[bman13]

One more question for Mickey or anyone else that knows what they're talking about. I know that synthetic oil chemically attacks silicone.For example, it's not recommended to use a synthetic gear lube in a differential that use rtv in the axle seals. Could this potentially cause a problem when useing rtv as a base gasket?
Great thread btw and thanks for all the info guys.

[Dunlap]

That is a good reason to ONLY use Honda's HT sealer.

[bman13]

Originally posted by Mickey Dunlap
That is a good reason to ONLY use Honda's HT sealer.


Thanks Mickey.

I assume that the Honda HT isn't formulated with silicone?

[SnellCRP]

Question for Mickey: With the thin head gasket and no base gasket where does that put your deck height?

[Dunlap]

You should have .040 clearence between the piston and head.

[Hondaluva]

Do you have to paint both sides of the single layer of head gasket? And again, what is the reason for the paint?

[UglyMotha™]

yes you have to paint both sides the paint is for sealing purposes and you can only use pink if you don't want it to blow :o

[300exQuadracer]

i`ve allways run 2 layers and some times one on my r and never had problems with the 2 layers but the 1 layer allways seems to blow after about 5 hard rides

[gojk]

I have tried this twice now in 1 1/2 weeks, and both gaskets have blown. How much paint are you using? I think I put on like 2-3 coats? Is that too much.
As soon as the cylinder heats up it seems to push the paint out and it blows the gasket seal. I didn't use high temp paint. Would that work better? I am using the cometic steel gaskets with no base gasket(which is holding up fine). I made absolutely sure that the surfaces were spotless before I put the last gasket on.

Also I am running a Wiseco 11:1 piston.

[toby400ex]

Anyone know what my compression ratio of my 11:1 je 426 should be with no base gasket and a cometic .047 headgasket should be?:confused:

[cals400ex]

Originally posted by gojk
I have tried this twice now in 1 1/2 weeks, and both gaskets have blown. How much paint are you using? I think I put on like 2-3 coats? Is that too much.
As soon as the cylinder heats up it seems to push the paint out and it blows the gasket seal. I didn't use high temp paint. Would that work better? I am using the cometic steel gaskets with no base gasket(which is holding up fine). I made absolutely sure that the surfaces were spotless before I put the last gasket on.

Also I am running a Wisecom 11:1 piston.


the surfaces on the head and cylinder should be cleaned with acetone really well. make sure your torquing down the head to the proper torque. it is possible that the studs are pulling out. make sure to use a high quality paint and make sure the gasket your painting is clean and dry. let the gasket fully dry before installing. you DO need to use a high quality high temp paint also. my friend is using the top layer of his cosmetic flexsteel gasket with good success. he first tried the middle layer but it blew over time. you can see that the middle layer is really thin on the flexsteel gaskets. i believe the top and bottom layers are the same.

[F-16Guy]

Okay; as far as the base gasket goes, these are my opinions:

1. On a stock bike, there is a chance that using gasket maker instead of a base gasket could lead to a partially blocked oil passage due to squeeze-out.
2. Making sure the surfaces are clean and true, spreading the gasket maker with your finger to a uniform thickness should reduce the chances of squeeze-out getting into the passage.
3. (Here comes a plug, Mickey) Using a FST top end cooler will eliminate the problem all together because it bypasses the stock passage. You will also get a bike that runs much cooler and holds more oil. :cool:

[Billdog350]

Ok, stock head gasket, no base gasket (just a thin bead of gasket maker like RTV sealant)...I got that down.

10.8 compression for a std bore (85mm) piston from JE....but if I remove base gasket it'll up me to about 11:1.....but the squash area will be better so it'll run cooler.

So, using the above concepts...IF I can run 93-94 octane with the 10.8 kit....I should be able to run the same for the 11:1 (without base gasket), correct? I'm planning on removing my timing advance key and jetting it properly of course...I'm just trying to stay away from the $10/gallon race fuel that everyone likes to run.

[UglyMotha™]

Originally posted by gojk
I have tried this twice now in 1 1/2 weeks, and both gaskets have blown. How much paint are you using? I think I put on like 2-3 coats? Is that too much.
As soon as the cylinder heats up it seems to push the paint out and it blows the gasket seal. I didn't use high temp paint. Would that work better? I am using the cometic steel gaskets with no base gasket(which is holding up fine). I made absolutely sure that the surfaces were spotless before I put the last gasket on.

Also I am running a Wiseco 11:1 piston.





you using the wrong kind of paint, it has to be high temp paint, normal paint will not stand up to those temps and go figure your gasket is goin to blow

[Aallron]

One thing to keep in mind is that on chain driven overhead cam motors is that when you change the distance between the original height of the head to the case either by shaving, or gasket thickness, you are altering the cam timing slightly. The performance gain you feel is probobly due more to altering the cams than from the marginal compression increase.

[Billdog350]

oK, so the cam timing is advanced due to the different distances? If so, is this at all detremental to the motor?

[lilpoppy]

The base gasket you guys are talking about is the one under the cylinder correct? As for the head gasket it doesn't matter which piece of the 3 pieces that you use?

[gojk]

Originally posted by lilpoppy
The base gasket you guys are talking about is the one under the cylinder correct? As for the head gasket it doesn't matter which piece of the 3 pieces that you use?

It has worked alot better with using the top or bottom layer. The middle layer is really thin.