EC 250 top rebuild question

[julianorettore]

Good Morning
I am making the top end rebuild of my gas gas 250, year 2008, I verified that the motorcycle has a wossner 8052DB piston, measure B, in which when measuring the piston I found that the lower diameter is larger than the diameter n top, measuring 66, 39 and 66.29 higher. Is that correct?
I noticed that there is a rebound in the cylinder at the top, where there is the end of the course of the rings, I believe the cylinder will have to be repaired. When I get home I will add photos so that you can help me more precisely
(translate portuguese > english by google)

 

[Zman]

Hello,

The top of the piston expands more than the bottom because of the combustion heat.

The ridge at the top of the cylinder can be repaired by having it replated. If you give the plating company the new piston they can hone the cylinder to the proper size for the piston.

 

[Zrt1200]

That is normal for the top of the piston to be smaller than the bottom of the piston. The reason it is that way is because the top of the piston expands a lot more with the flame on it.

When measuring piston diameters you measure at the bottom of the skirt. As for your ridge. Is it wore in where you can feel it?? A lot of times a quick hone will take that mark out.

 

[rossi]

I'm assuming that the ridge at the top isn't due to carbon build up above where the bore is swept clean by the rings?

If it is carbon a quick rub with a scotch pad should be all that is required to remove it.

 

[julianorettore]

I'm assuming that the ridge at the top isn't due to carbon build up above where the bore is swept clean by the rings?

If it is carbon a quick rub with a scotch pad should be all that is required to remove it.

Good Morning!
So yesterday I talked to a gas dealer near my town, where he informed me that the wear that exists is normal because the piston does not work in that area, where the head is fitted. The piston had no carbon deposit but I noticed that the gap of the rings was 0.90mm (in the manual service it is 0.40 to 0.70 mm). The rings will be replaced, the power valve will be cleaned and the engine reassembled. I noticed that there are several gaskets with a total of 0.85mm, if I put a single gasket of 0.5 or 0.3mm, I lose very top end? I know I'll get low end.
Thanks!

 

[julianorettore]

Hello Friends!
https://youtu.be/9IcoTymJabA
This is a basket for my GG 250, it is normal ??????????
How to solve this problem ?
As far as I can tell, this is the source of a noise that my bike has, the sound of the noise coincides with the noise that is made when I press the basket.

Whaiting.....suggestions

 

[Zrt1200]

So the rivets are loose correct??

 

[julianorettore]

So the rivets are loose correct??

The rivets are secured, the crown has a transverse clearance (according to the video), and has no clearance in the direction of the crown
Now wants to know if this transverse gap is normal or not (translate by google)