250 Rebuilding KX250

[ossagp]

Well yah, but the nice thing about it is sending an A sized piston can be replace with the following letters and your guaranteed a good fit through the years, without much skirt slap. But the size difference is minimal, so to each his own, and peace of mind. Especially if it's you personal ride.

I have done the abc's. Pretty much stuck to cast pistons with that. I was hoping that wiseco would start building pistons for motorcycles like they did the kt100 kart engines. Pull those up online if you want to see what I mean. You can effect a range lots further than ABC.

 

[AdamRides87]

Normal wear? Found these super fine shavings in where the crank bearing sits. They are metal pieces as they stuck to a magnet

 

[2strokesteve89]

View attachment 28045

View attachment 28046
Normal wear? Found these super fine shavings in where the crank bearing sits. They are metal pieces as they stuck to a magnet

Yup......normal wear for a bad bearing, looks like some aluminum also. Make sure the bearing didn't spin in the case.

 

[AdamRides87]

Yup......normal wear for a bad bearing, looks like some aluminum also. Make sure the bearing didn't spin in the case.

I don't believe it could have spun in the case... The bearing was not seized and spins freely. I think it's just smoked

 

[ossagp]

Fyi there are lots of metals( from aluminum to zink) which are NOT magnetic. You may want to remember that, if you ever intend to work with metals or need something from someone who does. All in all it would end a conversation with several of the people that I have learned from.

 

[AdamRides87]

Fyi there are lots of metals( from aluminum to zink) which are NOT magnetic. You may want to remember that, if you ever intend to work with metals or need something from someone who does. All in all it would end a conversation with several of the people that I have learned from.

Sorry. Was just being general. It's SOME type of MATERIAL that is not aluminum

 

[ossagp]

I like the way you tested it.

Just know how it sounds. Hell, maybe you won't ever run into anyone that will notice.

 

[AdamRides87]

I like the way you tested it.

Just know how it sounds. Hell, maybe you won't ever run into anyone that will notice.

Fair enough haha. Do you think it's part of the piston? It does have rather deep gouges in the side

 

[ossagp]

If it was part of the piston, it wouldn't come up with the magnet (unless it picked up steel filings). when you find iron and steel in a motorcycle engine it came from a shaft, a pin, a gear, a fastener, retainer etc.

 

[AdamRides87]

If it was part of the piston, it wouldn't come up with the magnet (unless it picked up steel filings). when you find iron and steel in a motorcycle engine it came from a shaft, a pin, a gear, a fastener, retainer etc.

Alright. Just kinda has me worried

 

[ossagp]

Well as you stated, a bearing on its last legs. You got the full benefit of that engine. Nothing says abuse or neglect. Just use.

 

[AdamRides87]

Well as you stated, a bearing on its last legs. You got the full benefit of that engine. Nothing says abuse or neglect. Just use.

I'll obviously give it a thorough cleaning and keep an eye peeled for anything suspect

 

[ossagp]

It's pretty classic of bearing wear. On the primary gear side?

 

[AdamRides87]

It's pretty classic of bearing wear. On the primary gear side?

Yes sir

 

[ossagp]

Usually is when I find it. The gears are trying to push themselves apart under power. The end of the crankshaft flexes over. If you find it on the magneto side you usually have a bent ignition rotor. Exception for lack of oil etc.