Your joking! What don't you like the look off I don't understand?

Sorry, but I`m not joking. Maybe the quality of the picture is too good. That is why I made the comment of the gray plug before. From where my eyes see it. It looks like those small bits are the rod coming apart, and you should not have so much wear on the new plating already. Just get a second opinion from some one physically looking it over.

Sorry, but I`m not joking. Maybe the quality of the picture is too good. That is why I made the comment of the gray plug before. From where my eyes see it. It looks like those small bits are the rod coming apart, and you should not have so much wear on the new plating already. Just get a second opinion from some one physically looking it over.

What small bits are you talking about? and what rod the con rod? and why would there be ware on the cylinder to slack? Sorry for all the q's but I want to get to the bottom of this and ride it Saturday..

This is a used cylinder I just sold on EBAY to a happy guy in France.

Yes, It was lightly used. But not new.

You have little small bits on the piston and in the head.( Unless that is just small water particles.) Rub your hand over them to see if is rough. Myself, I would pull of the exhaust just to double check how the piston looks. I`m not trying to ruin your ride tomorrow. Like I stated, hard to give a good opinion on this forum.

I don't see what lineaway is seeing

When you have a Rod failure you take it apart because it stops running or is making severe knock, when a rod goes it stops running in well under a minute

What happens is the lower rod bearing and cage come apart and migrate up the transfer ports, the debris catch between the edge of the piston and the cylinder and there is baaaad damage, long scratches above the transfers, it's generally fairly large pieces not tiny dust size stuff

Also the piston and head as well as the spark plug get sandblasted, often the debris closes the plug gap stopping the engine, the bearing, cage and thrust washer are extremely hard material compared to the aluminum piston and head

It does however look in the photo to have a lot of light vertical scratching in the bore but I don't know if it's just reflection or not, need a naked eye on that

If the light scratching is there it's probably more poor air filter maintenance than rod bearing failure

Edit: Ya after a second look there is a great deal of scratching in the bore but again, more likely to be dust ingestion or perhaps ring end gap is too tight (called ring butting) often it does more damage than that though

Edited December 27, 201312 yr by 0007

Not knowing what issues he had before the rebuild, it is hard to say about the rod. I`ve seen hundreds of rod failures. Those small specks could be brass shavings. That is what I see at first glance. No matter, it is hard to believe that is a fresh rebuild

Noting wrong with the grey coloured plug - run 'em rich to keep them from stalling and give good throttle pickup.

I've never ever ever ever got a good plug colour reading from a trials bike. If you manage it please let us know how to get it.

Modern fuel doesn't seem to give a good plug or tail pipe colour..... Or am I just dreaming?

Ride your bike it is fine

Ralphy

I also wouldn't worry about the plug colour. It 's almost impossible to give carb tuning advise when you don't know if everything else is perfect and in wat condition the engine was running right before he shut the engine down.

Even though it's hard to give an opinion based on photo's, I have to agree with lineaway: that cilinder has a lot of scratches for one that's only run for 3 hours.

You mentioned in your first post you cleaned out the bottom end, what was in it? Maybe that explains the scratches...

That's a film of oil on the head and piston crown it isn't pitted I had the bottom end pulled apart to make sure there wasn't any crap in there when having the cyl re plated and new piston and ring because it was worn.

The lad who striped it down and rebuilt it said the bottom end was pretty clean with just a bit of gunk at the bottom.

The filter was clean and well oiled so I don't know what could of made the scratches although there not noticeable to the touch.

I pulled the exhaust off and the same scratches are noticeable on the piston.

As I said, it 's hard to judge from photos but I wouldn't be too concerned. Just put it back together and enjoy it.

Mate don't get the bore replated. I've seen near new bikes with similar scratches. Put it back and ride it. It'll be fine.

It`s not fine, the bike broke today but seems to be other issues.

I don't think his bike having no spark today, has anything to do with the tiny scratches on his cylinder.

It`s not fine, the bike broke today but seems to be other issues.

So it's not running due to scratches on the bore?