top end- with pics and a trashed head!

[the_privateer]

piston after I cleaned it up with a scotch brite, looks ok. its got about 12 hours on it, no color on underside. just lots of carbon on top, leaking crank seal I think


take notes kids, saves tons of time on re-build



this picture has no real purpose, I just wanted to show off my banner

[RoostRM125]

My local shop just sanded my down and polished it up with an air tool. It made it nice and smooth. Just clean it up.

[jhendrix]

My cousins head looked like that, except it wasn't a full circle of it, just a few rough spots that looked just like that.

We sanded it down a little and cleaned, and it came out pretty smooth, not like new, but good enough to use.

[Jethro]

Just use fine sandpaper take any points off that may cause pre-ignition. Blurry picture but it doesn't look all that bad (I've seen worse!).

[AV8R]

I'd want to make sure whatever did that was gone. Flush bottom end. flush out the pipe.
Try to find out how this happened. It does not look like detonation.
Is there a piece of something missing that flailed around in the cylinder for a while?

[Jethro]

Originally Posted by AV8R

I'd want to make sure whatever did that was gone. Flush bottom end. flush out the pipe.
Try to find out how this happened. It does not look like detonation.
Is there a piece of something missing that flailed around in the cylinder for a while?

The marks on the head look like old scars to me since the piston's not showing any damage. The marks weren't caused by detonation or pre-ignition, but any single points on that damaged head surface can heat to the point that they can cause pre-ignition this is why any points should be rubbed down.

[Jethro]

Man, just noticed that you've got one post more than me AV8R... Just had to even that up there

[dhighlan]

Looks like my bull dogs chew toy after he has had it a couple days.
Are the marks carbon or are they flat holes? Hard to tell from that pic.

[E-man811]

That makes me shiver......

Did you recently buy this bike?

Ian

[the_privateer]

they look like little puncture marks, not just carbon. It wasn't like that less than 12 hours ago when I put the piston in, but the piston and cylinder look fine (still haven't spec out cylinder to be absolutely sure) and that has me stumped. I couldn't find any signs of dirt anywhere in the bottom end either.

I've had the bike for about a year and a half, this is the 4th top end I've done on it. besides the head, the powervalves where swimming in oil but everything else looks clean.

[char393]

It sure looks like something was in there to me.

I had a similar looking one when a wrist pin failed, which was probably due to a leaky crank seal...


At the time, my cylinder was also scored, so I took the opportunity to send it to Tryce at Fast Forward Racing. I now have a 144 pinger ready to go back together, just as soon as I find the time..