head gasket replacement

Not a fan of using RTV, as even the thinnest coating of it, will cause a bead on the inside of the engine.
This bead will definitely be right in the middle of the transfer ports, and any restriction in that area in my opinion, does nothing but hurt performance.
gaskets work fine, and do not have any of these worries with them.

its not that the bigger issue is clearance the gaskets are perfect thickness with rtv sealant your not going to get the right squish may even harm engine if piston hits the top which it will you can apply thinly to gasket if wanted but new gasket clean surfaces is enough

on my engines I use the copper gaskets these work good and on my billet obr case the 2 halves has no gasket and is sealed by RTV but cases have been machined for this

Have done the RTV head gasket mod, been proven on pocket bikes // piston port and reed engines. There is a slight improvement in peak power, the engine feels more alive, and has a cleaner top end. Make sure surfaces are clean, place oil moist paper towels stuffed into the crank so any old gasket material scraped off sticks to them.

Place a thin coat of orange high temp gasket maker (about $8.00 or so in Auto Zone), let it dry for a minute or so to get some consistency and then let the cylinder head lay on top of the block, hand easy tight (do not squeeze out the sealant). Let it dry out to its gummy cured state, then proceed to cross tighten the head to the block. Do a heat cycle (drilling the four holes in the plastic fan cover helps), and re-tighten.

The RTV mod is a old trick, proven on 2-stroke 49cc pocket engines, and those engines do rev high sometimes into the 12 to 14k pushing an old fart like me.

And yo

crankestein said:

Have done the RTV head gasket mod, been proven on pocket bikes // piston port and reed engines. There is a slight improvement in peak power, the engine feels more alive, and has a cleaner top end. Make sure surfaces are clean, place oil moist paper towels stuffed into the crank so any old gasket material scraped off sticks to them.

Place a thin coat of orange high temp gasket maker (about $8.00 or so in Auto Zone), let it dry for a minute or so to get some consistency and then let the cylinder head lay on top of the block, hand easy tight (do not squeeze out the sealant). Let it dry out to its gummy cured state, then proceed to cross tighten the head to the block. Do a heat cycle (drilling the four holes in the plastic fan cover helps), and re-tighten.

The RTV mod is a old trick, proven on 2-stroke 49cc pocket engines, and those engines do rev high sometimes into the 12 to 14k pushing an old fart like me.

Click to expand...

Found this to be reliable?
I'm just 50/50 at this stage in doing so.. but I'm quite keen to do it if I get the reliability
Cheers

Its a gamble for sure... I did it the mod on a fuelie engine. The most that will be lost is wrench time, because it either works or get a air leak right away and then throw the mod out the window.

Yeah it was reliable. Seriously, when I did the mod I could not believe it myself it held compression and never over heated. I will see if I try it out on one of the engines, take a few snap shots and report back. Just been lazy on doing the mod again.

Have used high temp gasket sealant on a turbo to the downpipe, without a metal gasket and no leaks. Those turbos get extremely hot, and worked well. I think the issue is going to be if the deck is flat making a perfect seal.

I would not recommend using silicone do to gas eats it. this is why the fuel lines on gas engines are made of tygon. silicone is ok for nitro but not gas. If you look at the link under suggested applications it says

• Suggested Applications: Valve covers, oil pans, timing covers, water pumps, thermostat housings, transmission pans. nothing that has to do with raw gas.

Go to pocketbikeplanet, its proven and I have done it, does work.

There are tons of things that have many other uses not posted in the back label.

Did you know toothpaste is better than any cleaning detergent for bath tubs, showers?

Its called the gasket mod in PBP.

You sure don't know what you are talking about, its a proven mod that many included myself have done. Use Yamabond and you will be fine.

wow you do not even Know me or what I do for a living and yet you say I do not know what I am talking about. silicone is not gas prove this is why it is not used on intakes or carbs or gas tanks. put some in a glass of gas and check it after a week.

On the same token, I have done the gasket yamabond mod, it does work, proven on may two stroke pocket bikes.

Its my opinion, the same you got yours, I bring up actual facts, not reading the manufacturer's label.

I am pretty sure you follow the label recommendations "drink responsibly" LOL! ditto, good for you, here is a cookie.

rager33 is correct, and there are different types of silicone RTV, and some are Definitely not good to use as a head gasket around fuel.

Some are better at taking fuel than others, but that is why there are so many options of RTV sealant available.

The correct one to use, if you chose to do so would be Permatex Motoseal.
https://www.permatex.com/products/uncategorized/permatex-motoseal-1-ultimate-gasket-maker-grey/

Not arguing that other things wouldn't work for a while, but they are not correct.

Post #8, Yamalube / Yamabond.

You know what, don't do it, if you still in between two waters on this thread, this mod is not for you.

Attached is the link explaining the Yamabond and also JB Weld.

User EPR is a well known member of Pocket Bike Planet. He has used both, Yamabond and JB Weld, in this case the YB on a C1 bike. This is not your typical weed eater motor with 30.5cc engine, this a track race bike.

http://www.pocketbikeplanet.com/82-air-cooled-pocketbikes/81910-rtv-silicone-base-gasket.html



And the list continues, this is nothing new, its an old do it yourself garage trick.

http://www.pwctoday.com/showthread.php?t=363323
Post #6

Just to be clear, I have worked in the auto repair industry for over 30 years, so no need to explain any of this to me.

crankestein, I am just not sure why you chose to be nasty to someone trying to help.

It was you on another forum that had never heard of using mixed mineral oil as a break in procedure for engines, and was ashing questions about that.
Learning is all part of this game, and respect for others is the proper way to handle things.

Properties of certain silicone products do not lend it to fuel applications.
Yamabond is a very good RTV typeproduct, and I am sure Very capable of being used that way.
The Permatex product I posted, Motoseal, is an equivalent in an aftermarket form.

Just trying to keep the information provided safe for anyone to use, and Not have problems.
Also cost effective as well.
Motoseal on Amazon like $6.00
Yamabond on Amazon like $12.00

Very good chart for aftermarket Permatex products, and the Proper uses.
https://www.permatex.com/wp-content/uploads/2015/12/Permatex_GasketMakerSelector.pdf

More good information on sealers, and gasket compounds.
https://www.hemmings.com/blog/2013/09/13/tech-101-how-to-use-the-right-gasket-sealants/

Good info here on the chemical properties of RTV type Silicone products.
http://www.adhesivesmag.com/articles/87551-fuel-resistant-rtv-silicone-adhesive

You are way off on all of this.
I am not addressing you on any matter, this is for the forum, not for you.
Here we are not debating about mineral oil, but I have already said the same thing multiple times. The fact that you have rolled back to other threads trying to find something wrong or noob like about me makes you fail in your actions, low and cheap.

Just stating an honest observation, I have provided more than enough proof that its a mod been done and proven. I have stated I have done it. I care less if you are the first mechanic of the world, the logic does not match one w the other. BUT you did say other things are incorrect, when post #8 is stating Yamabond, in other words my posting is incorrect. EPR is a well known member, he knows his deal. I read his thread and did not take me anything else to give it a try and it does work, of course I tried it on a used Fuelie, and the engine ran exceptionally well.

I have not been rude, but realistic. The user who started the thread sounds nervous and too insecure and just because of that he is not ready for this mod.

These are weed eater motors, including the over-rated OBR etc engines.

Have a great day, or don't, no matter to me.

ok I have to jump back in here. first of all I mean no disrespect to any one. Just trying to help the original poster. I am a engine builder. I will try to explain what happens when you lower the cylinder. First it changes squish velocity. second it changes compression. third it changes port timing. fourth most of the time on zenoah motors it creates free port. Now to explain. Squish velocity is the speed at witch the air fuel mixture is forced from the outer edge of the cylinder to the center. this is important because you want mixture to be condensed around the plug at the time of ignition. raising the compression can be a bad thing for rc car. when you raise it you loose rpm(top speed). Remember this is a RC car the motor only has to push around 25 pounds not 200 like a pocket bike so it does not need as much torque. When you lower the cylinder you lower Exhaust timing and increase intake timing bad combo for RC car. Free porting is when the piston is at top dead center and because the cylinder was lowered the intake and exhaust ports are open at the same time. the exhaust port should be completely blocked by the piston skirt at tdc. Last and most important you should never make clearance changes without taking measurements first. Again this is not meant to disrespect anyone just trying to help.