1977 25hp Johnson Opinions

[kbait]

Re: 1977 25hp Johnson Opinions

You could use muriatic acid sparingly. Just be ready to water-rinse immediately to neutralize it.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

If I am just doing the cross hatch sanding on the cylinders and pistons do I need to use the acid?

 

[ultra353]

Re: 1977 25hp Johnson Opinions

Use the acid first to remove any of the piston material that is left behind on the cyl walls. Wear rubber gloves and eye protection when doing this. After all the aluminum is gone then use the sand paper.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

Whats the process for applying and using the acid. I have no experience with doing any of that so sorry for sounding like a noob.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

When i am putting on new gaskets do i need to put gasket sealer on them? I know that i do not need to on the head gaskets but what about on all the others? thanks.

 

[castires]

Yes, apply it to all of them, except those on the intake side.

 

[F_R]

Re: 1977 25hp Johnson Opinions

Use sealer on the exhaust cover gaskets.

Did you hone those cylinders and replace the pistons and rings? If not, it really doesn't much matter what you do from this point forward.

The pistons on a two stroke act as VALVES. The piston skirt seals the area between the exhaust ports and the crankcase (where the intake is). A lousy fit or scratch marks allow air/exhaust to bypass back and forth from intake to exhaust and back. If you put those junk parts back in there you will get what you built.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

So I took the advice of everyone on here and replaced my rings and pistons and got the cylinders boared out. I just have a few questions now as I start putting everything together. Any help would be greatly appreciated.

Do i need to oil up the pistons when I put them back in the cylinder?
What types of gasket sealant will work? I dont have many marine places to go to, so the more options the better.

Thanks.

 

[ultra353]

Re: 1977 25hp Johnson Opinions

Yes all the pistons/rings/bearings lube with oil. Make sure the cyl`s are clean( no black looking material on a light colored towel when wiped) and lube up the cyl`s as well. More oil is better than less oil when your putting it together.
Crankcase- use a gel type sealer like yamabond 4 or omc`s brand
Head gasket should already have a factory sealer applied( if it looks shiney its on there)
Rest of gaskets use like an brush on sealer or 3M 847( carefull on the intake gaskets, don`t get any on the reeds)
Don`t use the permatex black or blue sealants.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

Okay thanks, are those sealants easy to come by or is it something I will have to order? Im hoping to get started on this in the next couple days and dont want to have to wait a long time to get something shipped.

 

[brycebell]

Re: 1977 25hp Johnson Opinions

I am having trouble finding these sealants. Are there any others that can be used and where's a good place to find them?