OzVMX Forum
Clubroom => Tech Talk => Topic started by: Turtle.Inc on March 30, 2011, 08:58:26 pm
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??? :'(
The 490 had a little nip up on the weekend, whats your view
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom004.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom003.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom001.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom002.jpg)
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Was that the first time out on that piston/bore Ross?
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Was that the first time out on that piston/bore Ross?
Five /six meetings on bore, has not been apart, went from Bing to Mikuni and reset the timing on the PVL to 2.2 BTDC, dont know wether its Timing or Carb related or both :-\
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That's physical damage; something metal has been bouncing around in there :-\
IMHO
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Looks like it's munched up bits of metal from somewhere? Somethings been hammered around on the top of the piston and head. Doesn't appear to have siezed from the pics.
Are they big end needle bearings embedded in the piston?
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Looks like it's munched up bits of metal from somewhere? Somethings been hammered around on the top of the piston and head. Doesn't appear to have siezed from the pics.
Are they big end needle bearings embedded in the piston?
Wouldnt think needle bearing would get up past ring, its been cooking from the top of the piston down at a guess, bigend feels good, no little end damage, air filter neat seal, no leaks around manifolds
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That's physical damage; something metal has been bouncing around in there :-\
IMHO
Bore not bad either considering, would think anything in topend would blow out pretty quick anyway
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I think i can see indentations from something steel in the alloy piston and cylinder head. Circlip?
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Needle bearings dont go past rings, they come through the transfers. That is definately metal damage, some thing has been floating around in there. Really check out the big end or little end.
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If all you have changed is the carb and timing I would say they definately play a part in it.....maybe lean then starts pinging and excessive heat so the piston starts disintigrating and thats the bits of metal jammed in the head.... :-\
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its DEFINITELY done the big end or a main bearing
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I think i can see indentations from something steel in the alloy piston and cylinder head. Circlip?
Both were intact, I'll have to get some good light down bottom end but initially feels good, will have to have a closer inspection in better light
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most of the above
check big end or main bearing cage
it doesnt have steel reeds does it ???
nice job anyway ;D
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I am leaning toward some sort of foreign body to Ross, but how and from where ??? is the $64,000 question.
Is all the piston ring still there? including the anti rotation pin? What about the head of the decompression valve? still there? When the new mains went in, did the retain plate screws get thread-locker and center popped?
Lets hope its not a end cage or main. Good luck.
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That's physical damage; something metal has been bouncing around in there :-\
IMHO
+1 + bigger than circlip !
cheers a
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most of the above
check big end or main bearing cage
it doesnt have steel reeds does it ???
nice job anyway ;D
Always nice to kow your work is always appreciated :-[
No reedsI am leaning toward some sort of foreign body to Ross, but how and from where ??? is the $64,000 question.
Is all the piston ring still there? including the anti rotation pin? What about the head of the decompression valve? still there? When the new mains went in, did the retain plate screws get thread-locker and center popped?
Lets hope its not a end cage or main. Good luck.
Ring and rotation pin still there still there complete, stuck but complete, decompressor etc all good, retain plates centre popped and loctited,
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Run a magnet over the slug & the head,that may tell you if its bits of steel or alloy imbedded in there.
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Tertell,bottom picture of piston,that bit of foreign looking material embedded above the ring dead centre looks sus,if it;s not metalic,it's track,your;e aircleaners failed ;), :P
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no matter what has done it, you need to pull it down to the bottom end at MINIMUM to assess it.
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my votes on a crook bottom-end.
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Part of the cage from the big end or little end bearing?
The 175 top end I had on my DT125 swallowed a rock at Canberra - I discovered it as a tiny, rectanular block lodged in the spark plug. New plug and it did three more race meets.
Eventually I convnced myself that it was down on power, so I ripped the top end off - it looked a lot like that, except the entire top ring land and top ring had disappeared.
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I Reckon your Engine problems will help you forget your Clutch issues ::)
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17yr old boy child suggests- its detenation running too lean....cheers A
perhaps ask Lozza ;D
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Thats what my piston looked like after it dropped the little reed cage screw.
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??? :'(
The 490 had a little nip up on the weekend, whats your view
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom004.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom003.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom001.jpg)
(http://i255.photobucket.com/albums/hh160/rosco400_photos/pistom002.jpg)
I reckon it's gonna be expensive and you need a decent camera ;D ;D I doubt you have a jetting or timing issue. There looks to be no sign of detonation on the head or crown, and that thick black layer on the head tells me(amongst other things) that your still on the safe side of a seizure. I would run with the general theme of metalic objects and looking at the size of the marks I woul have said a ring expander, but they don't run them so I would agree with Hoony and say a cage disintergration with the rollers still in situ(making the big end 'feel' OK). Rollers make a big mess , but have had a KX 60 big end bearing completely vanish.
If the big end cage/thrust washers are in tact the only other possiblity is maybe something from inside the carby.
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Turtle stop bitting your finger nails :D ;D :D ;D
Have to agree with Snowy 76 this makes the clutch problems seem minor
Piston looks exactly like mine did after the little end cage failed last year on my 250. Everything bearings wise looked and felt fine until I tried to remove the wrist pin >:(. definitely a foreign object of some type.
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I kind of side with Alison's 17 y/o. Looks like pre ignition/detonation to me also.
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"I kind of side with Alison's 17 y/o. Looks like pre ignition/detonation to me also."
Me too. Had a IT175 running 125 electrics & did exact same thing.
I know there are signs of metal floating around;
Question: Is there a small fragment of spark plug missing?
Maybe a combination of both.
Had a 125 let go a bit of big end cage and looked like the piston side shot but no where near the damage on top.
Detonation are explosions of the bad type and the head & top of piston look exactly like that. You mention you changed ignition/timing?
Viper666
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What oil ratio was being used?
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Looks like a bit like detonation but somethings deffinatly been banging around inside there. Looks like a small roller about a mill and half wide. Put us out of our misery and split the thing....
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What's this? Looks like something embedded.
(http://i323.photobucket.com/albums/nn458/mx250syd/OzVMX/pistom002-1.jpg)
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It's not the air jet or part of used on bigger mikuni's ? which could lead to leaner /detonation :-\
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The head shows black divots everywhere(marks were made before combustion), detonation blasts the chamber clear the combuston chamber and piston. Deto also erodes the timing edge of the piston.
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I'll near bet it's pre ignition/detonation and the reason the divots in the top of the piston are black is simply because the engine was being ridden hard whilst detonating. Did it have a horrible rattle under load like terrible gudgeon rattle (pinging) and did you keep on the gas whilst it was making such noise? The fragments are bits and pieces of molten metal from the piston crown and cylinder head. Check the port edges also as these can fragment under such conditions.
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Detonation will give a blistered surface on the piston crown but it simply cannot create the small, sharp edged divots the Turtle's piston has.
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Whatcha reckon we run a book. ;D
1/ bet evident damage is
a/ physical, as in a bit broken off and bounced around on top of the piston.
b/ pre-ignition/detonation.
2/ Further bets,
if bet for a/ the cause was;
a/ little end break up
b/ foreign matter
c/ big end
d/ reed bits
e/ carby bits
f/ others
if bet for b/ the cause was;
a/ ignition timing
b/Jetting
c/ combination of a/ & b/
or you can bet it was;
a/ act of God
b/ act of Turtle
c/ typical of a female (Kattie in this case :D)
My bet is $10 on Physical and $10 on the little end (and that's the remains of a roller embedded ;))
Turtle is 'house' and gets 10% of all winnings for providing entertainment value ;D.
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1a-c
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OK, I'll have another stab at it.........it's farked....beat that!!!!!
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OK, I'll have another stab at it.........it's farked....beat that!!!!!
Wanta bet? :)
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Have a look at piston pin C clip is there a piece missing ?? Bet 2 f
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I Reckon I may not have to race against the big girl on the weekend .
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Turtle`s got other bikes to ride!
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1/a/a.... little end bits tapdancing... ;)
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I wasn't talking about his bikes Snowy
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Ten bucks on the nose of Davey Crocket.
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I know its hard to hear things when you are traveling at light speed with a helmet on.
But did it rattle more when it was under load, acceleration up hills? or did it rattle just as much when you were of the gas, closed throttle?
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They don't call it death rattles for nothing. No offence to anyone as some may not know what it sounds like but if you can't hear detonation then you'd have to stone deaf ;) even under full noise with ear plugs and helmet you can't miss it nor could anyone standing trackside within any sort of earshot. I've seen quite a few smaller capacity engines with exactly the symptoms as shown and whilst I'm not saying there isn't something foreign I still say main problem in the first instance is detonation. I'll zip it now and wait for the verdict ;)
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No shit, Sherlock. But there is a difference. Was the bulk of the noise when on the gas or off it?
And there is such a thing as dignity and grace when not trying to offend.
Noise would have started at the beginning of its demise. If the noise was just as great when off load and without the song of the exhaust, it definitely started mechanical intrusion or failure.
If basically the bulk of the noise started when under the load of acceleration only, well then it definitely started as a detonation problem.
I was politely trying to pick Turtles mind for the facts.
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The fragments are bits and pieces of molten metal from the piston crown and cylinder head.
Yes 17 yr old said the top disintergrates.Too lean :'(
I'm still with mx250 some other item.
I know its hard to hear things when you are traveling at light speed with a helmet on.
Don't hear a thing-its all in the eye's :o :o
cheers A
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Was the noise when on the gas or off it?
It took 17yr old three laps to work out "it aint right" and three pistons later to get it all good.
cheers A
a snippet found from superhunky;
Turning and roosting in the widening gyre
The rider cannot hear the camshaft chain;
Things fall apart; the crankshaft cannot hold;
Mere anarchy is loosed upon the world,
The oil-dimmed tide is loosed, and everywhere
The ceremony of inexpensive repair is drowned;
The best lack all conviction, while the worst mechanics
are full of passionate intensity, and drunk. ;D
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Was the noise when on the gas or off it?
while the worst mechanics
are full of passionate intensity, and drunk. ;D
Well I haven't been drinking, so I can't be Drunk.
Passionate,,,,always.
Half of this working life as an engine builder all around Oz, from formula Cos-worth two stroke outboard blocks and up to engines larger that most peoples bedrooms with never a failure and optimum log bog entries. But don't forget all the tech of those space shuttles and one only lasted seven seconds.
Well I have lasted three days. Maybe Its time to get three largies instead. Yeap, thats whats wrong with it, signing out.
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I doubt that thing blew up through detonation, the piston and cylinder head are embedded with little pieces of steel not alluminium.
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Have a look at piston pin C clip is there a piece missing ?? Bet 2 f
Nah but i have found out so will upload a few pics, still taking bets MX250 :DI Reckon I may not have to race against the big girl on the weekend .
I wasn't talking about his bikes Snowy
You guys crack me up dudes.
17 year olds "A" they think they know everything but how often are they actually right :D
They don't call it death rattles for nothing. No offence to anyone as some may not know what it sounds like but if you can't hear detonation then you'd have to stone deaf ;) even under full noise with ear plugs and helmet you can't miss it nor could anyone standing trackside within any sort of earshot. I've seen quite a few smaller capacity engines with exactly the symptoms as shown and whilst I'm not saying there isn't something foreign I still say main problem in the first instance is detonation. I'll zip it now and wait for the verdict ;)
Doc I am profoundly deaf in the high end scale but no indication prior to nipping up, death rattles I am familiar with ::) after all it is a maico
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17 year olds "A" they think they know everything but how often are they actually right :D
[/quote]
They are like a Lotto tickets.You just never know,if they will hit the jackpot ;D ;) ;D
cheers
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Johnny O closely followed by Head By a short neck to Hoony for the betting man
Love the repies though, Tamika big end kit fitted approx 12 months ago bit sus, wont be going down that path again
Now ya seen em
(http://i255.photobucket.com/albums/hh160/rosco400_photos/bottomend005.jpg)
Now ya dont
(http://i255.photobucket.com/albums/hh160/rosco400_photos/bottomend007.jpg)
Forgot to add running at 33:1 Maxima 927 which has always been good thing
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I think me and Hoony will have to split that big novelty cheque ;D More importantly why has the cage gone south ;) ?
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I think me and Hoony will have to split that big novelty cheque ;D More importantly why has the cage gone south ;) ?
I was hoping someone could tell me :-\
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I think me and Hoony will have to split that big novelty cheque ;D More importantly why has the cage gone south ;) ?
Oi - thirds, I think! :-*
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I was hoping someone could tell me :-\
It's right there, or rather what's not there. 'Outskips' should have to answer some hard questions.
Nathan 1/3 of some IOU's is still nuffin ;D
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Graham picked it, too. We're all winners here !! :D
Oh.....sorry about your bike, Turtle... :'(
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Graham picked it, too. We're all winners here !! :D
Oh.....sorry about your bike, Turtle... :'(
Thats ok, I'm used to it :D
I was hoping someone could tell me :-\
'Outskips' should have to answer some hard questions.
Yer like that will happen ::)
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Take a feeler gauge and see if it fits between the crank web and thrust washer ;)