best piston for 250es big red?

[Mr.Atc]

Have a nice 85 250es that my grandpa bought years ago from his friend who was the original owner. It still has the original piston in it and runs strong but burns a little oil. It probably just needs valve seals and rings but if im going to tear it apart I might as well replace everything. What piston will give me the best bang for my buck?

[barnett468]

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Howdy!

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Below are a few options. I would also have the cylinder inspected. Most likely it will at least need to be bored. See free online original service manual at bottom of post for repair info.

You can still get the original rings in all sizes and pistons in .050 and 1.0 from the link below. The orig .025 and .075 pistons are discontinued but can occasionally be found on ebay or other locations.

.025 orig piston p/n 13102-HA0-305, this is a good deal. You might consider buying this or other orig in this size before it's gone

http://www.ebay.com/itm/NOS-Honda-ATC250ES-ATC250SX-TRX250-25-Piston-OEM-13102-HA0-305-/190864159060#ht_367wt_930

http://www.google.com/search?q=13102-HA0-305+EBAY&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a


Stocks many NOS OEM parts.

http://www.cmsnl.com/honda-atc250es-1985-big-red-usa_model966/partslist/E++12.html#results


Japanese made orig replacements are available in the link below.

http://shindypro.com/piston_kits.html


Wiseco does not list them.


Orig service and owners manuals.

http://www.atcmanuals.info/


Here’s my avatar. I named her Bacon. Isn’t she cute?

Hi, my name is Bacon Aren't I cute.

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[dougspcs]

If you tear down the top end and take your cylinder into a machine shop that specializes in honing/boring and piston replacement it's gonna be your best bet..

They'll mic the cylinder bore and determine how much they need to cut to get back to a true cylinder..then measure to see what oversize piston to fit or if it's needed at all. They'll either tell you what oversize piston you need or offer to supply it.

Some who have done the process in reverse..namely buy a piston then take the cylinder in to get bored out have ended up with a piston they couldn't use.

A simple but properly done top end job and all that it entails should give you the best performance and hopefully another 30 years of running! Not a huge market for performance replacement parts for the 250ES...

Or listen to the pig..you're call!!

[ATC-Eric]

Which piston is the best? The one that is the right size. I would pick up a nice stock style cast piston as a replacement. No need to stick a high dollar Wiseco in there.

[barnett468]

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Hi Mr Atc;

http://t0.gstatic.com/images?q=tbn:ANd9GcTDheK_NT7A9cIdJnV_1Pg7lGbLDWNu5 AVQnY60FToKElt_Wip72n1nHA



...take your cylinder into a machine shop… They'll mic the cylinder bore… …then measure to see what oversize piston to fit or if it's needed at all.Xlnt idea!

From reply 1.

I would also have the cylinder inspected.





Some who have done the process in reverse..namely buy a piston then take the cylinder in to get bored out have ended up with a piston they couldn't use.
From reply 1.

The orig .025 and .075 pistons are discontinued… ….025 orig piston p/n 13102-HA0-305, this is a good deal. You might consider buying this or other orig in this size before it's gone.This was obviously just a suggestion, not a message of impending doom. http://www.freesmileys.org/smileys/smiley-laughing013.gif (http://www.freesmileys.org/smileys.php)


1. FACT – The orig .025 and .075 pistons are discontinued.
2. FACT – They as well as many other orig parts for these old bikes are getting harder to find and more expensive as time goes by.
3. Imo, the likely hood of your cylinder needing to be bored more than .025 based on your description thus far is obviously possible but highly unlikely.
4. If you buy the piston and it is determined that you do not need it, you can likely sell it fairly quickly on Ehay at a price less than you paid for it.




Or listen to the pig..you're call!!Xlnt choice!

http://t3.gstatic.com/images?q=tbn:ANd9GcQxr9P5OYMQvRhaWZ5QfBVTS7isj4zCS JQ6Ku1TmxO1HY-ScDvHod7NuYM


OMG!
http://www.freesmileys.org/smileys/smiley-laughing025.gif (http://www.freesmileys.org/smileys.php)

:beer

[Chopsaw]

Maybe check compression before you tear it down ? That might be the place to start .

[barnett468]

.
Hello Mr Atc;


The shindy pistons are around $75.00, I would prefer to run an orig honda one as my first choice but these are good a I mentioned and they are readily available.

http://www.ebay.com/itm/Shindy-Piston-Kits-04-052-SH04-052-/331128155829#ht_1518wt_930

[6speedthumper]

Maybe check compression before you tear it down ? That might be the place to start .

Well, he has adequate compression. That's why the engine starts and runs, lol. Compression test will only state how much cranking compression the engine has, not if the cylinder needs to be bored to the next size piston. An engine can have poor compression from a stuck, or broken, ring; but the cylinder is still in fine shape, and thus only needs a re-hone to deglaze it, and new rings installed. That is an example. Many cracked rings damage cylinder walls. Didn't want to get my head bit off, haha!

For me, if I know the current bore size, I just buying the next size over piston and have the cylinder reworked for it. Sure, there are cylinders out there that only need a re-hone and you can stick with that bore size. But, many times, the cylinder is out of round, or just slap worn out, so it needs to be taken to the next size anyway. In most cases you're spending the same amount of money for the piston and the machine work, regardless of piston size. I'd rather have a fresh bore/hone/piston kit, then a re-hone depending on how worn the cylinder is. Wear is wear; a cylinder bore's diameter only gets larger with use. It may be within spec when mic'd and honed, but, how long before it's out of spec and needs another top end? Again, depending on the cylinder's wear. I had a spare cylinder for my Fourtrax 300 4x4 that came off a 2x4 parts bike I had, and it couldn't have had more then twenty hours on that parts bike! Crosshatch on EVERY SINGLE surface of that cylinder, and it was well on the new side of the tolerances when it was mic'd. I just had it re-honed. I mean why not? It was practically new! Lol. But, then, that one may have been an exception... Anyway, there's my .02

[6speedthumper]

Oh, Mr ATC, you wanted people's opinions on the best piston choice. For me, it's always Wiseco or JE. I prefer to run forged pistons in my bikes. But, the factory Honda cast pistons have been more then proven durable. Can't go wrong either way.