blew up my top end

[Brandonj]

well I just took my head apart and found that I have holes all around the outter edge of the piston like someone took a ball peen hammer to it and my piston slammed in the head so my head is beat to ****. now would antifreeze in my oil cause this? also my clynder walls are still nice and smooth but do I still need to have it bored? .and can someone help with rebuilding my top end like is there a post already on how to do this. and help me with parts. i also have pics tht I'm up loading right now and should be up here any minute now

oil


head


piston

[CarGuy7a]

What's this in? 2 stroke dirt bike engine?????

[cuda_tmaxx]

now would antifreeze in my oil cause this? also my clynder walls are still nice and smooth but do I still need to have it bored? .

A couple of things.

Would coolant in the oil cause this- No.

Coolant will turn your oil milky white. It is hard to tell what color your oil is.
However, if you have coolant in the oil you have a serious problem, most likely a bad lower jug gasket, but I have seen many cracked crankcases cause this. Also, Honda CR's from the mid 80's- mid 90's were notorious for having the crankcase/gearbox right side plate deteriorate at the waterpump allowing coolant into the gearoil. Your clutch will not be long for this world.

The damage was caused by an object that made its way into the cylinder, whether it be a piece of ring, bearing, spark plug electrode or other miscellaneous debris. In most cases it will be something metal that eventually worked its way out the exhaust port.

As for a bore, you should have good cross hatching, but you can probably get away with a set of rings and a piston.

Buy a repair manual for the bike and it will have a good walk through, including torque specs.

[Brandonj]

What's this in? 2 stroke dirt bike engine?????

sorry guys I got lazy last night and just copied my post on the dirt rider forums to here. it's a 2003 honda cr 125 2stroke. the bike doesn't have a lot of compression but being towed I can dump the clutch and it'll fire up and run crappy.

[NStampede Freak]

Check your rod bearings. I have a bike that looked like that after the lower rod bearing let loose.

If it's a two-stroke, the oil has nothing to do with the engine. It is gear oil for lubing up the tranny.

[Brandonj]

ya that popped in my head during my enignes class today. guess my source of info isn't as reliable as i thought. lol

[RC-MXer]

your gonna need to take the cylinder off and take it to a bike shop or machine shop and see if they can bore it bigger or yoy might have to re-sleeve it. your gonna need a new piston. wants you your cylinder is off play with your rod and crank to feel for play to see if your bearings are bad.

[brushlessman]

seen it before. one time the air cleaner wing nut in my 79 truck fell into the carb. and got trapped in a cylinder.

[RC-MXer]

My little brother races 85's and has gone through a crank and 3 cylinders and pistons. its and 08 too, one of them was becuase dust got in and tore it up.

[harry697]

Edit.nevermind

[harry697]

sorry guys I got lazy last night and just copied my post on the dirt rider forums to here. it's a 2003 honda cr 125 2stroke. the bike doesn't have a lot of compression but being towed I can dump the clutch and it'll fire up and run crappy.

There is definately a piece of you motor somewhere that is missing.That's what did all that damage.Could be a variety of things(ring,piston skirt,bearing,wrist pin clip,etc.)Pull the cylinder and check the piston really good.Make sure the whole ring is there(the ring is not a complete circle.There is a small gap in it).Also check to see if both wrist pin clips are there,the wrist pin bearing is whole, and that the piston is whole.I've seen a few Honda's that have had the piston skirt break completely off.Most of them were 250's but I've seen it on 125's and even a few 2004 CRF 250's that have done it.

BTW,pullstarting it is not doing anything but making matters worse.

If it's a two-stroke, the oil has nothing to do with the engine. It is gear oil for lubing up the tranny.

Yes it does.They are supposed to be seperate,but it is possible to get water in your trans oil.I have seen crankshaft seals fail and oil gets in the water and vice versa.That rubber seal is all that seperates the trans from the crank case.The rear water pump seal can also have the same effect but is not very likely.A cracked engine case can also do that.I would still venture to say that the crank seal is the most common reason for oil/water mixing on a 2-stroke though.