Is my cylinder trashed?

[BoCFes]

I'm pretty new to dirt bike engines, been working on cars for a while though. I'm rebuilding my top end and honing my cylinder. While i was inspecting the cylinder i noticed a space between the cylinder and the intake (where the reed valve pushes fuel through i guess). It looks as though the metal might have been worn down and that space shouldn't be there. Can anyone tell me whether or not my cylinder's trashed?

Here's a pic from the bottom of the cylinder.


Here's one from the top looking down through the cylinder


Here's one from the bottom left


Like i said, the surface around the inside of this space looks pretty worn.

[dogger315]

Can anyone tell me whether or not my cylinder's trashed?

Hard to tell from the pictures but your cylinder may have been resleeved.
I recommend you use a dial indicator and caliper to measure the bore in a
half dozen different locations top to bottom and at right angles to each
other. You are checking for I.D., out-of-round and taper. Pay close
attention to the suspect area. Service limit for the cylinder is 66.44 mm,
out-of-round is 0.05 mm and taper is 0.05 mm. Normal cylinder I.D. is
66.390-66.405 mm

What are you using to hone it?

dogger

[BoCFes]

Originally Posted by dogger315

Hard to tell from the pictures but your cylinder may have been resleeved.
I recommend you use a dial indicator and caliper to measure the bore in a
half dozen different locations top to bottom and at right angles to each
other. You are checking for I.D., out-of-round and taper. Pay close
attention to the suspect area. Service limit for the cylinder is 66.44 mm,
out-of-round is 0.05 mm and taper is 0.05 mm. Normal cylinder I.D. is
66.390-66.405 mm

What are you using to hone it?

dogger

I've actually already done that, he cylinder is in specs and decent shape, and it is a sleeve job. The matter im asking about is the space that i've circled in the pictures (big red circles with arrows), is that supposed to be like that.
And i'm just using a honing brush for it. my brothers sending me the right one. should only take a couple strokes.

[dogger315]

the space that i've circled in the pictures

That space is the result of the resleeve. The new sleeve is not
the same wall thickness as the OE. Since you already checked
what matters inside the cylinder, you are good to go.

i'm just using a honing brush

I recommend a ball hone (360 grit). Gives good results with a
45 degree overlap pattern. Breaks the glaze and provides a
real nice surface to seat new rings and promote consistent
oiling.

dogger