What should the cylinder sleave look like after the break in period on a two stroke motor? Some people are telling me that the cross hatching will be rubbed flat in some spaces,and some people tell me the cross hatching should stay there. after about an hour or two of breaking in,My quad seems to run great and strong,but i took the head off to make sure and check out the bore,and the cross hatching is being smoothed out around the intake and exhaust ports.on the exhaust side,theres even an area that has been smoothed almost to the point of being "shiny"under the exhaust port. I am not running lean,and im almost positive i dont have any air leaks (new everything), So what should a decently broken in cylinder sleave look like? i forgot to mention,the piston looks good still on both sides

 

If it a'nt broke don't fix it.

 

If the piston looks good, no worries. The wear pattern will be what it will be, there's not much you can do to ensure even wear. Like Swansonator said, if it ain't broke...

 

superevil the reason you are seeing the polishing under and around the ports is because of extrusion and compression of the metal. When any cylinder is clamped down it distorts; even 4 strokes with no windows in them. It will twist and squirm and bend. In very small amounts, but it still dose this to one extent or another.

In the automotive racing world a good machine shop has torque plates that they will bolt to the block to simulate the stress when everything is bolted together. This way everything is round when bolted together. I've even heard rumors that some high end shops run heated water through their blocks when boring. Some racing automotive engines run 18 thousand RPM and need all the help they can get to stay together and make power.

Now in the quad world, I know of no shop that has torque plates. Maybe some of these high end engine shops do? I just don't know. Would it be a good idea? Yes it would, but shops get by without them so they don't worry about them.

What your seeing is what usually takes out a two stroke. The shop will get the bore a little tight and maybe the builder will torque the bolts down a little bit too tight and the thing starts to scuff in that area. Then it heats up and scuffs a little more and on and on until something gives up.

Like others have said, I would not worry about it. USUALLY a two stroke will give up under it's first heat cycle if it's not machined or put together right.

 

i wasnt to worried about the flattened cross hatching,but i was worried about the shinny area under the exhaust port,im just going to make positively sure i am not running lean,and just ride it out and see what happens. sound like a plan?

 

i thought i was overheating at first and making the piston swell up. but i took the reeds and exhaust off to look and the piston looks happy. for the record i am really impressed by your relpies. i hate asking my shop these questions becuase sometimes they can make you feel stupid. i am new at this,but i put this engine together from a box of parts and invested about 600 bucks while doing it. people like "doctorturbo" are why this site is awesome. i really do like the "if it aint broke" responses as well,nothing like a good smack in the head sometimes to make me stop being paranoid!!! HATS OFF TO YOU GUYS

 

Thanks for the complement superevil.
The rings are responsible for the shiny spots. If the metal in the cylinder is high around the port window from the clamping force, that spot will get worn away and get shiny. I'm not saying to do this but if you were to pull the jug and look at the ring in that spot it will be very shiny in the matching spot.
It's people like you that that learn very fast. You rebuilt your own engine and sounds like you did a great job.
PS. I wish I had hard snow like that around here. I got my V really stuck about a month ago. Now it's 82+ around here.

 

Do you think i should keep riding and cross my fingers? or should i have it checked out at a machine shop or something? actually,the part where it was shinny was on the exhaust side towards the bottom where the rings dont even touch.

 

I thought this was where the ring package was riding.
If the rings arn't ridding where the shiny spot is then it's the piston that is wearing on the cylinder? If so, and the piston is not scored, just buffed, then I would not worry about it at all. Even very light scoring is ok in my book. If the piston is showing heavy scoring then I would start to worry.
Like I said above, it sounds like you did a great job of rebuilding it. I think you will be fine, go out and ride it.

 

I like the "if it aint broke dont fix it"... but i like even more "if it IS breaking, fix it before it messes up more than just that part of your bike and you are stuck 10 miles from the middle of nowhere next to a big expensive immobile broken POS."