Need some advice on a rebuild- 85 XR2

sb220

Cadet
Joined
Feb 27, 2009
Messages
13
Well I was having problems with my number 3 cylinder being out of specs with the others...after de-carb I was getting 115-120 psi across the board and 100 psi on #3. I pulled the head and found this...




So Ive never gotten as deep as I plan on going in an engine before, but am confident I can do it with the right tools and information.

So as far as tools are concerned let me know if Im missing something.

Wrenches, sockets, screwdrivers are covered
Engine lift
Engine stand
Lifting eye
flywheel puller
piston expander and compressor - as far as these are concerned is it necessary to have the mercury tools here or can I pick up auto tools if the piston size is within the ranges? The merc compressors Ive seen are incredibly expensive.

Now to pick your brains. My plan was to have #3 bored and put a larger piston/ring in there. Then have the rest honed, install old pistons with new rings....replace gaskets, button her back up and get back to fishin.

I see and understand the issue with "good" cylinders being out of round, but will honing usually take care of this? If so, will old pistons usually work with a cylinder that has been rounded/honed as long as it has new rings?

Thanks for your help
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,930
Re: Need some advice on a rebuild- 85 XR2

If your going to bore one just bite the bullet and bore them all. I have yet to see a engine over 10 years old that wasnt worn close to max spec's or out of round. Just do not put Wiseco pistons back in it. You cant hone a cylinder back straight, the honing stones will wear to the cylinder shape as you cannot remove that much material. If you do then it will be past spec's and need bored oversize anyway. You dont need a engine stand, a milk crate cut off to 4" high works fine(use the bottom) to undress/redress block. Here is link to a good ,cheap ring compressor and pliers you will need. Get the 2284 ring compressor and the 33500 ring pliers.

http://images.google.com/imgres?img...ers&start=20&ndsp=20&um=1&hl=en&sa=N&ie=UTF-8
 

sb220

Cadet
Joined
Feb 27, 2009
Messages
13
Re: Need some advice on a rebuild- 85 XR2

thanks...why not Wiseco though?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,930
Re: Need some advice on a rebuild- 85 XR2

They are good pistons and if you dont add the extra bore clearance and ensure thermostat/cooling system works properly they will stick. The piston expands faster(forged) than a stock(cast)piston, so if customer dont not lets engine idle to get some temp in the block the first time ya plane off piston skuffs/sticks. If customer wants Wiseco I bore block extra .0005 and hone for clearance. Stay with a cast piston and you will have no problems.
 

sb220

Cadet
Joined
Feb 27, 2009
Messages
13
Re: Need some advice on a rebuild- 85 XR2

Sounds like good advice, thanks.

While I have you here....money is the option. All new bores and pistons Im looking at over a grand.
If I could bore the bad hole and replace that piston only Im down around 300-400 with gaskets/seals etc.

If the economy and work was booming it wouldnt be a question, but unfortunately budget is most important thing at the moment.

so...if I was to just bore cylinder 3 and replace that piston. Even if the others were out of round, could I essentially put the old pistons and rings back in after inspecting them? (I have always had good compression on other cylinders in the years that I have owned it)

Is it just an issue of "you've got it to this point so why not go all the way for longevity reasons" ? Or will the mating of the old pistons/rings to the untouched cylinder walls not form the same "bond" that they had before I took it apart.
 
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