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thats probably a valve or rings. both easy fixes. the left looks pretty good though. whatever you do, dont use the head that came off it with out scrutinizing it pretty closely.

jc
 

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Is that a broken stud on the right?
I can't tell from the photo, but is the piston damaged or just carboned up?
Did you do a compression test before you got into it?
What do the valves look like?
What the hell is going on?

FR
 

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Discussion Starter #4
The valves look okay. There is a lot of carbon build up, but also a nice quarter size divit in the top of the piston. I have no clue what could have caused it.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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I think they are the same pistons even though one has a carbon build up which shows more piston diffinition .My first look Id thought the same.Id have a machine show check out the head .was the oil very gassy smelling,in the case, could also be that carb out of whack. or ring.
Hind sight compression test before tear down,if valve check out by a machine shop and have a valve job down .Id do rings at this point while the head is out.oh well one thing leads to another .

and I wonder too, is that a missing stud in the middle right

a quarter size divit im not seeing it in the shot

any screws or springs valve missing from the eternals of you carb (may have injusted a loose part) it has happened

Im so far behind ,that I think Im in first.

Edited by - LilBull on Jun 23 2007 07:55:52 AM

Edited by - LilBull on Jun 23 2007 07:58:09 AM

Edited by - LilBull on Jun 23 2007 08:00:01 AM
 

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that is a broken bolt. if that bolt wasnt sealing up, theres a good chance you had a serious comp leak. i didnt realize that round thing was a flat spot in the crown. if you need cyls, let me know, i have piles of them. you,ll of course have to get them bored. or at least mic and hone em. those are probably usable though since they seem to be stock bores.

jc
 

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Discussion Starter #9
Yeah, I should have done a compression check. This was a spare motor I had sitting around. I figured I'd check it all out. Learn a bit about these motors on the spare one before I start taking apart the No 1 engine. The stud on the right comes out. It was sloted in the top end, I have it.

I just thought it was interesting how the one piston was so knackered. There was lots of carbon buildup on the valves, but they were okay. I have heard that if you get lots of carbon buildup that it can heat up soooo much that the piston can fail as showen. Don't know if that is how this happened or if that is true. Just thought I'd post it for conversation purposes.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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i have a few sets of pistons and some of them have a small raised ring in the center that appears to be from the casting process could it be that the piston was under poured? i'm curious to know if the pair are balanced or not.

...connoisseur of slack...
 

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Nothing to worry about in that circle in the center. That's just a difference in machining. Its not damage. The idiot that was running the machine that popped out that piston has probably whittled 45000 pistons that day, and bored the piston pin a little too far out.

The piston is fine. I've seen a couple like that.
 

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Nothing to worry about in that circle in the center. That's just a difference in machining. Its not damage. The idiot that was running the machine that popped out that piston has probably whittled 45000 pistons that day, and bored the piston pin a little too far out.

The piston is fine. I've seen a couple like that.
 

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Discussion Starter #14
Great, thanks. Good news.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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Discussion Starter #15
Great, thanks. Good news.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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Discussion Starter #16
quote:
quote:Yeah, I should have done a compression check.
WANKER!!!

JS
and proud of it! The good thing is that I usually learn from my mistakes, sooooo....Wankers = Mistakes = learning = MENSA membership.....wonder if they race on the weekends?

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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Discussion Starter #17
quote:
quote:Yeah, I should have done a compression check.
WANKER!!!

JS
and proud of it! The good thing is that I usually learn from my mistakes, sooooo....Wankers = Mistakes = learning = MENSA membership.....wonder if they race on the weekends?

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 

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Peter,
The guy I got my TA from was a MENSA dude. The TA was all wrong...just ask Fred, he got the Bultaco from him too and he had to fix ALL his improvements. Just give me or Fred your motor, we will fix it!!

JS
 

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Peter,
The guy I got my TA from was a MENSA dude. The TA was all wrong...just ask Fred, he got the Bultaco from him too and he had to fix ALL his improvements. Just give me or Fred your motor, we will fix it!!

JS
 

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Discussion Starter #20
I may not be smart, but I am such a smart ass that MENSA should give me an honorary membership.

Yeller'
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Ask not what the wanker can do for you, but what you can do for your wanker!
 
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