Post by: beaner on December 13, 2012, 03:14:03 AM
Wiseco piston has been in the bike for 3 years, but I was hurt and hardly rode it for 2 of them. I installed a new ring last spring, and raced it at 6 events this past season, and probably a dozen practice days. I rode it hard and it ran flawlessly. The ring is like new, and well within spec. The piston looks like new with the exception of the specs (looks like salt and pepper) on the top, but mostly concentrated on the top OD where it looks and feels like it's been glass beaded.
None of the previous 3 pistons in there looked like this, and I have made no changes. There was no indication of dirt or dust in the intake (it's all removed) and nothing unusual on the plug.
Post by: msmola2002 on December 13, 2012, 04:01:33 AM
Post by: factoryX on December 13, 2012, 04:26:23 AM
Post by: beaner on December 13, 2012, 04:49:50 AM
Post by: msmola2002 on December 13, 2012, 06:14:00 AM
Post by: TMKIWI on December 13, 2012, 06:49:31 AM
You may have a very small water leak , probably around the head o-rings.
Check underneath the piston as well. If there is any sign of water ( clean area's ) it could be coming from the base gasket.
Post by: TotalNZ on December 13, 2012, 09:21:30 AM
I don't know how you can stand to run 91, mt bikes hate it the TM won't run on it.
Post by: 2T Institute on December 13, 2012, 12:31:56 PM
Detonation occuring
Jetting rich
Post by: ford832 on December 13, 2012, 01:20:51 PM
Yeah i'm thinking coolant getting into the combustion chamber too but i haven't seen it look like that.
I don't know how you can stand to run 91, mt bikes hate it the TM won't run on it.
Looks like water ingestion to me as well.
91 octane is our supreme.You guys use RON ratings.We use an average of RON and MON-called AKI(anti knock index)It's usually written on the pumps as (R+M)/2) That means our rating is about 3-4 points lower for the same fuel.Not as bad it sounds but we've recently had to have 10% ethanol in our regular and midgrade swill.(87 & 89)Fortunately,our supreme is still free of it-for now.
Post by: SachsGS on December 13, 2012, 03:41:20 PM
Post by: beaner on December 13, 2012, 04:55:28 PM
Thanks for the replies.
Post by: ford832 on December 13, 2012, 06:57:35 PM
Post by: Stusmoke on December 15, 2012, 09:04:40 AM
Post by: beaner on December 15, 2012, 12:08:08 PM
Anyway, I found something interesting when I pulled the head. It's not related, I'm sure but it looks like a casting defect, and some material may have come off and banged around a bit. Typical Suzuki
I'll post a pic later.
Post by: 2T Institute on December 15, 2012, 12:31:25 PM
The orange crap on the crown looks like ring blowby, but its on a certain area of the piston.
It called a wash pattern, hotter areas of the piston cause the oil 'char' and stick to the piston , no charring no heat on the piston.
Post by: Stusmoke on December 15, 2012, 11:34:02 PM
The orange crap on the crown looks like ring blowby, but its on a certain area of the piston.
It called a wash pattern, hotter areas of the piston cause the oil 'char' and stick to the piston , no charring no heat on the piston.
Then I retract my statement. Thank you
Post by: Stusmoke on December 15, 2012, 11:37:22 PM
The orange crap on the crown looks like ring blowby, but its on a certain area of the piston.
It called a wash pattern, hotter areas of the piston cause the oil 'char' and stick to the piston , no charring no heat on the piston.
Hopefully that will be your answer and its a short adventure. The salt and pepper definitely looks like debris
Post by: 2T Institute on December 16, 2012, 01:50:10 AM
Post by: beaner on December 16, 2012, 03:04:04 AM
Post by: 2T Institute on December 16, 2012, 12:43:01 PM
Post by: beaner on December 16, 2012, 07:13:20 PM
The combustion chamber is stock.
Post by: 2T Institute on December 16, 2012, 08:35:49 PM
Post by: cnrcpla on December 16, 2012, 09:44:08 PM
Quote
Water ingress would crack a hot piston instantly, usualy between the timing edge and the ring gland.Yeah. It happened to me once... If I can find the pic of the piston I will put it up.
Post by: bearorso on December 16, 2012, 11:11:56 PM
04 RM 125.
Wiseco piston has been in the bike for 3 years, but I was hurt and hardly rode it for 2 of them. I installed a new ring last spring, and raced it at 6 events this past season, and probably a dozen practice days. I rode it hard and it ran flawlessly. The ring is like new, and well within spec. The piston looks like new with the exception of the specs (looks like salt and pepper) on the top, but mostly concentrated on the top OD where it looks and feels like it's been glass beaded.
None of the previous 3 pistons in there looked like this, and I have made no changes. There was no indication of dirt or dust in the intake (it's all removed) and nothing unusual on the plug.
Given this information, and if you've not got a deterioration of sealing components - water, air - and the time line of the bike having no use, I'd tend to think that it may well be a reflection of the crap that is being passed off as fuel, nowadays. The variations in my bikes' running, can be quite marked, be it in getting fuel from the same supplier / pumps (because ever more frequently, servos are just getting fuel from whoever they can), or when travelling.
It's the major reason I am considering going back to race fuel - the belief in / hope for consistency, and getting What I Pay For. Even AV gas is something I'm considering again - on a lightly stressed 500, it's good enough, and it's controlled enough still, I hope, to be consistent in it's chemistry. And it's a lot more affordable than race fuel.
Post by: beaner on December 17, 2012, 12:05:45 AM
Water ingress would crack a hot piston instantly, usualy between the timing edge and the ring gland. Have you measured the squish gap? What fuel was it running?
I don't think I would agree with that. I've put lot's of water through some of my race motors without any problems.
As I said before, it was the same 91 octane that I've always used, even from the same place. It's also the same fuel I used in my other bikes this past season.
I've been dealing with a machine shop for the last 20 or so years, to do the things I can't do in my own shop. They are engine builders, primarily, and build some of the better race motors locally. I had to stop in today, so I showed it to them. They said two things. That's preignition, not detonation, and whatever it was that caused it has either been fixed, or went away on it's own, because it's old damage (which I think is obvious).
Post by: SachsGS on December 17, 2012, 01:03:03 AM
Post by: riffraff on December 17, 2012, 04:28:57 AM
I can't get over HOW CLEAN portions of the piston crown are, very strange.
It is awfully clean, and the dark areas are on the intake side. What's the head look like?
Post by: 2T Institute on December 17, 2012, 10:48:36 AM
Post by: TotalNZ on December 17, 2012, 11:45:53 PM
1's a 2000 YZ125 which was put together after it blew up with a needle roller still floating around inside.
That needles jammed in there tight.
The next is a 2006 KX250 thats leaned out and destroyed itself.
Would you believe that pistons 10 hours old apparently
Post by: Stusmoke on December 17, 2012, 11:54:00 PM
While we're on the subject of piston analysis, check out these 2 rebuilds i've got on at the mo.
1's a 2000 YZ125 which was put together after it blew up with a needle roller still floating around inside.
That needles jammed in there tight.
The next is a 2006 KX250 thats leaned out and destroyed itself.
Would you believe that pistons 10 hours old apparently
What. The. F**k. Someone neglected to do the wristpin bearing in the last dozen rebuilds. Thats messed. Hows old mates cylinder head and wall?