How do i get it out

[Eddiesanders250]

Well i was riding and yea my piston seized, i know what it was caused from thats not my question. my question is how do i get the piston to break lose from the cylinder. I was thinking heating it up?? what do i do its stuck in there nice and tight?

[fireburns99]

you wouldn't want to heat it up, because the heat would make the piston expand. You could try heating up the cylinder walls, but i'm not sure if that would work or the effect it would have. I think you might be stuck with brute force.

[CQR]

You can try putting some muriatic acid between the piston & wall, let is sit a SHORT amount of time and see if it will help release it. the acid will work on breaking down the aluminum before eating away the cylinder wall. try to keep it away from the ports and make sure to neutralize the acid afterwards.(baking soda and water)

[Eddiesanders250]

Im afraid im going to hurt something by pounding it out. has anyone done this?

[tazman7]

Take a rubber mallet and use the handle of it to pound down on top of the piston.
dont worry about hurting anything, you will more than likely need to get the cylinder honed. But I would still be careful

(I just did this last week)

[Eddiesanders250]

yea im not worried about the walls at all i know im going to need to get it bored. What about the dome some chunks in the piston flew into it and scuffed it a little. will it be ok to run it like this or does it need to be cleaned up?

[tazman7]

It will need to get cleaned up.

Just dont stick a screwdriver and pry up on it in between that cylinder jug and the case. Thats not good. Rubber mallets are your friend

you might not need to get it bored either-unless you want to go that route anyways- usually if it isnt to scratched up getting it honed will work wonders

[Eddiesanders250]

thanks man it took me about a minute to get it unstuck lol. And the walls werent bad at all no bore needed ill hone it and a new piston is goin in. there were some little pieces from the piston that dropped down in by the crank, i think i will just pour oil down and try to flush them out. did you have that problem? thanks

[LT250RMan]

Use more than oil when washing out the crank case. Use some gas and a air compresser with the air gun end and blow out the crank case after you wash it with mixed gas and then do that over a bunch of times. Make sure there not any metal peices in the crank case because that will take out the bottom end bearings if theres metal in there. You dont want to wreck your crank it will cost you like a $1000 or more with labour if that happens..

[C-LEIGH RACING]

If the piston is stuck in the cylinder that bad from a seizure, I wouldnt just wash the bottom end out, I would pull the cases apart & replace some parts. Remember, when it seized it didnt just mess up the piston, it hurt the crank & the main bearings as well. Think where all those fine shavings went.
Neil

[LT250RMan]

Originally posted by C-LEIGH RACING
If the piston is stuck in the cylinder that bad from a seizure, I wouldnt just wash the bottom end out, I would pull the cases apart & replace some parts. Remember, when it seized it didnt just mess up the piston, it hurt the crank & the main bearings as well. Think where all those fine shavings went.
Neil

when an engine locks up it puts alot of stress on the crank bearings but it doent mean there no good, but its a good idea to check them out, and if something melted like the rings the hot metal would of went in to the bottom end with all the metal shaving from the cylinder wall.

[86 Quad R]

as stated............always!!!! i repeat always pull the cases apart when something happens to an engine like that. dont take long to do. no sense in cutting corners just to go back in there. :huh

[250r4life]

not everybody has the equipment lying around to split the cases all the time...

[pharit]

Originally posted by 250r4life
not everybody has the equipment lying around to split the cases all the time...

what equipment?

[rockman]

i think he means brain cells.. :rolleyes:

[Eddiesanders250]

lol well guys i checked it out more yesterday and there is a chunk of the sleeve from my cylinder stuck in the crank. so i know im going to need to split the cases and replace the crank and while im there ill go thru the bottom end and replace anything that looks like it needs replacing. C-leigh why dont you post much? I here good things about your porting.

[b.lee]

Originally posted by tazman7
Take a rubber mallet and use the handle of it to pound down on top of the piston.
dont worry about hurting anything, you will more than likely need to get the cylinder honed. But I would still be careful

(I just did this last week)


lol!! a hone job?? :eek2:
with the piston seized to the cylinder wall? :chinese:

i don't think so, from there on out, its all BORE jobs...

and if you want the bore job done right, you need to send out the piston you are going to use with the cylinder so the shop can mic it out / check tolerences between the 2.

[Eddiesanders250]

thanks man but lol thats not a concern right now. I chipped off a huge piece from my cylinder so it needs re sleeving. im splitting the cases right now.

[pharit]

Originally posted by Eddiesanders250
thanks man but lol thats not a concern right now. I chipped off a huge piece from my cylinder so it needs re sleeving. im splitting the cases right now.

Make sure you got that equipment that dude was tellin you about:huh

[spent21]

86 Quad R, what part of MS are you from? i grew up in Kosciusko, about an hour north of Jackson.

[C-LEIGH RACING]

Eddie,
I have other sites I go to more than here & all of them are 2 stroke sites. ATV Riders started our as EX Riders which is more of a 4 stroke site than a 2 stroke & I dont want to come on here & upset anyone.
One of the 2 stroke sites, r - c e n t r a l . n e t is where I'm at most of the time.
Thanks Neil

[250r4life]

huh- i was always under the impression that they are hydrolically pressed together, and that you after you split them you have to hydrolically press them together again... so i guess if i'm uniformed, why dont you go ahead and explain to me how to go about splitting the cases... i've done several top ends, but never a bottom end...

[rockman]

you need these:
8mm socket
rachet
rubber mallet


and VIOLA done!!!

oh yeah plus a little bit of finess

[rockman]

ok ok maybe not that easy but you get the point.. its not rocket science.. its pretty easy.

[C-LEIGH RACING]

So you never pulled a 250R bottom end apart, nothing wrong with that, lots of things I never done before myself, got to learn somehow.
A 250R engine, after you take all the bolts out of the case, lay it on the clutch side straight up & once the gasket is broken loose, the left side case half should lift right off with the crank intact. If the engine has an OEM Honda crank & OEM Honda main bearings, the crank should come off with the left side case.
On a 250R engine, the crank is a press fit into the flywheel side bearing & both main bearings on either side are press fit into the cases, but the OEM crank is a slip fit on the clutch side case half. That side of the crank has been machined to fit easy into the bearing race.
Splitting the cases on a TRX 250R atv engine & CR 250R bike engine are done the same way.
Both engines use the same main bearings, but the cranks are different.
Now a Honda CR 80 dirt bike engine, those engines are a press fit together on both side cases.
Neil

[beerock]

neil i rebuilt a cr80 motor and it came aprt almsot the exact same way a R motor was, the crank stays in the left side case. at least it did on the motor i rebuilt, maybe it changed through the years? think it was a 02

[250r4life]

hey neil- thanks a lot i appreciate it... i actually just blew my bottom end and was planning on having a shop do the bottom end and i was gunna do everything else... i guess i'll give it a whirl...

[wilkin250r]

Originally posted by C-LEIGH RACING
& I dont want to come on here & upset anyone.

Solid, technical information from a master engine builder isn't going to upset anyone. :cool: