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Discussion Starter #1 (Edited)
Saw this on another forum I frequent so I thought how about starting one on here?

This thread is for everybody who wants to post some pics they made!

This is a picture of my coworker driving on two wheels on his ATV in the sand dunes out here in Qatar.
 

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Discussion Starter #3
It was a mistake I was still working things out I was trying to get my image to show up in thread and not as an attached thumbnail. Do you know how I can do this?
 

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Discussion Starter #5
The .org don't allow it unfortunately - real shame, as forums that do are so much brighter IMHO!
Oh well wont hurt me too bad I guess I should also make it clear it the pictures can be whatever you like, but let's keep it safe for work fellas. (I enjoy the ability to be able to view this site on the job when a few others are blocked.
 

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Oh well wont hurt me too bad I guess I should also make it clear it the pictures can be whatever you like, but let's keep it safe for work fellas. (I enjoy the ability to be able to view this site on the job when a few others are blocked.
You can still use Photobucket etc, but only the link shows. It means we have to go to all that extra effort of clicking the mouse!

(I still think the site would look better with more pics though :thumb:)
 

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How about an engine failure pic?

CB250N was still running - but unbelievably rattly and smokey :)
If you look closely you'll notice that the nearest valve adjusting screw has been punched out of the rocker - that is the valve stem stuck through the hole!
Haven't had a chance to strip it yet but I've seen down the plug hole and into the intake and exhaust ports. The head of the intake valve is missing and much of the piston skirt has been shredded and punched out into the carburetor. The other intake valve is bent and twisted from being hammered into the port. The exhaust valve is just bent from being hit by the piston. I'll post some more pics as I pull it apart if anybody wants to see them.
 

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How about an engine failure pic?

CB250N was still running - but unbelievably rattly and smokey :)
If you look closely you'll notice that the nearest valve adjusting screw has been punched out of the rocker - that is the valve stem stuck through the hole!
Haven't had a chance to strip it yet but I've seen down the plug hole and into the intake and exhaust ports. The head of the intake valve is missing and much of the piston skirt has been shredded and punched out into the carburetor. The other intake valve is bent and twisted from being hammered into the port. The exhaust valve is just bent from being hit by the piston. I'll post some more pics as I pull it apart if anybody wants to see them.
I'd be interested Larry, post 'em up!
 

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I'd be interested Larry, post 'em up!

Okay then :)
The amount of force that was required to punch the valve stem through the rocker I'm really surprised it didn't keep going through the valve cover like a bullet. I'm guessing the other end of the valve stem is wrecked and jammed in the guide.
Building some history just now so I haven't had a chance to strip that one yet, but I will. Just started a CB750 SOHC engine build - the original "Japanese Superbike". All stock (unfortunately) but still pretty interesting to see where our bikes began :) A mate of a mate is doing a big rally in a few months and wants a fresh engine for it - so I immediately put up my hand to do it!
 

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Okay then :)
The amount of force that was required to punch the valve stem through the rocker I'm really surprised it didn't keep going through the valve cover like a bullet. I'm guessing the other end of the valve stem is wrecked and jammed in the guide.
Building some history just now so I haven't had a chance to strip that one yet, but I will. Just started a CB750 SOHC engine build - the original "Japanese Superbike". All stock (unfortunately) but still pretty interesting to see where our bikes began :) A mate of a mate is doing a big rally in a few months and wants a fresh engine for it - so I immediately put up my hand to do it!
Cool - that will be interesting too. I think any pics you take of your engine work will be interesting to a lot of us - we could all learn from it too.
 

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I did manage to pull the topend off this arvo (in 39C heat!).
We think the valve adjuster has come loose and wound its way most of the way out of the rocker as only the last few threads have been torn off the screw. Then we reckon the hole in the rocker has done the job of a valve spring compressor by banging on the spring retainer until the collets popped out. Then the valve has dropped into the chamber and been punched by the piston back up into the seat so hard that the valve stem has broken as there is no bending at all to the stem - it almost looks like it's been cut off on a lathe. The valve head has been bouncing around on the piston, smashing the valves and hammering the piston until it's made a big enough hole to drop into the crankcase.
And it was still running!
 

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:eek::eek:

What a mess!

What's the plan for repairing it then? (Or is it 'beyond economical repair' now?).

I think all CB250N's are by definition beyond economical repair :)
A mate of mine swapped in another engine and he knows I love examining engine failures so he gave me the dead one.
I guess I could conceivably find a use for it but they don't have a lot of potential. An odd sort of design with three valves, the crank is held in by an internal saddle arrangement similar to car engines, it only has five gears and it's not compact at all. The head bolts must be 200mm long. I'd guess the engine weighs around 60kg or more and probably puts out less than 20hp. I'd expect the 400 or 450 topend would bolt straight onto it but I don't think they made much more power.
 
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