Piston/barrel dramas

[TZ350]

There was only one circlip 'missing' well i found a third of it intact the rest had long gone.

Is there any sign in the grove that the pin has been hammering the clip?

[jellywrestler]

Is there any sign in the grove that the pin has been hammering the clip?

no i checked for that.
the bike run for aeons with the previous piston etc in it and with a mandrel i made fitted sits on the cases sqare both sides.
I did find the circlip in the front piston installed in a poor place. ie the end of the clip was in the relived area used for flicking the clip out, whereas it should be held in better, just poor trade practice really...

[TZ350]

Square across the cases, that’s a good way of doing it.

No hammering, nothing out of align, then pointing towards poor installation? Bummer

[Grumph]

Out of curiosity Mr Jelly, two quesions -
Again, was the more heavily damaged side, the plug side ?
And, when the front barrel was moved to the rear position, did the oilways line up ?

Thank you - and I hope you've learned from all this, never put "dramas" in a thread title, look at the angst you've caused......

[husaberg]

Out of curiosity Mr Jelly, two quesions -
Again, was the more heavily damaged side, the plug side ?
And, when the front barrel was moved to the rear position, did the oilways line up ?

Thank you - and I hope you've learned from all this, never put "dramas" in a thread title, look at the angst you've caused......

Drama and angst.You make it sound like a teenage soap.

I want my money back cause where's the hot looking chick with daddy issues? I want a boob shot. Or was that Neil?
Cause if thats the case I want my money back. We did get the cat fight though.

[pete376403]

Post #3 appears to be first correct answer, what do I win?

[husaberg]

no i checked for that.
the bike run for aeons with the previous piston etc in it and with a mandrel i made fitted sits on the cases sqare both sides.
I did find the circlip in the front piston installed in a poor place. ie the end of the clip was in the relived area used for flicking the clip out, whereas it should be held in better, just poor trade practice really...

Mr Jelly I googled the VOC (Vincent owner Club) site
"problem with Omega pistons VOC" should do it for you.
There is a write up somewhere on the site problems with Omega pistons
For some reason my computer won't access it as I think it has the flu or something
but have a look there and see what you find.

PS have you considered turning the Rapid into a Comet or better yet a Gray Flash? You are already half way there.

[pete376403]

Omega are (were) a recognised brand back in the day when I was racing speedway. My Weslake had an Omega, of all the problems that motor had, the piston wasn't one of them, and I'd suggest a speedway motor running at full tit is a bit more stressed than a Vincent on the road. But, as I mentioned before, I didn't use circlips, preferring teflon buttons (a wee bit heavier, but a shitload more reliable)

[husaberg]

Omega are (were) a recognised brand back in the day when I was racing speedway. My Weslake had an Omega, of all the problems that motor had, the piston wasn't one of them, and I'd suggest a speedway motor running at full tit is a bit more stressed than a Vincent on the road. But, as I mentioned before, I didn't use circlips, preferring teflon buttons (a wee bit heavier, but a shitload more reliable)

Re Omegas
They still are and I have heard only great things about them.
What does the write up say?
I don't know
Your piston/s were presumably forged. Are Jelly's I don't think they are by the look of them.Edit the pic one page back defiantly ain't forged.
The Britten ran Omega amongst others F1(Well the Blanks were).
For all I know the piston may have been done on a Friday, the manufacture may have been shipped offshore,They may have been roughly handled.The piston may have had an old circlip put in by mistake.There could have been a bad batch of circlips or just one.

Found this toohttp://www.britbike.com/forums/ubbth...&Number=236715

[Buckets4Me]

gudgeon pin circlip come out?

sounds like you where first to come up with it

and thats not a piston fault

[Spearfish]

All that happened from not getting the wee little clip fitted home properly or using the old ones.

At least the ones in the thread swinging handbags were standing up while the rest were sitting. Shits and giggles.

[bucketracer]

Real life experience or something from the net that Bucket clued me into ........ well who knows ...

Here is a very easy way of checking for a bent rod. Its such a useful assembly check I am surprised a certain someone else with a lot of industry experience hasn't mentioned it.



Hold the barrel down and then with the piston at TDC slide a feeler gauge around the top, if the rod is even slightly bent it will be tighter on one side than the other. When I was working a lot with engines, this was a standard test done on every cylinder as a double check for alignment issues. You could also feel for broken rings this way too.

And circlips were always given a half turn in their grooves to be sure they were properly seated and there was no foreign matter caught behind them. If the clip was not properly in its groove when you turned it you would hear it click into place.

Turning the clips, now thats another industry trick that someone in the know could have told us about too.

There was only one circlip 'missing' well i found a third of it intact the rest had long gone. The greater damage was on the side where the clip was out This is logical as teh clip would've hung around here in larger bits before breaking up and some travelling to the other side.

All that happened from not getting the wee little clip fitted home properly or using the old ones.

Dad tells me that its pretty easy to crush this type of circlip out of its round shape into an oval when fitting it, clips bent even slightly oval are weaker and don't have the right shape to withstand the accelerative forces at the end of the stroke and can easily pop out of their groove.




As well as pictures of various types of piston damage and their causes, distortion of circlips when fitting is talked about in at least one of the links to the engine failure manuals that I posted.

I am still unable to see any images even remotely like ... can someone point me in the right direction ...

SS90 if you can't find it, I will be happy to point it out, as a bit of reading can save even the wisest man from repeating his mistakes.

[jellywrestler]

Here's something else, there are two different size clips for the gudgeon pin, 54 thou and 64 thou, the 64thou ones being in the damaged piston and are a smaller 'loose' size
IE they nearly drop into the hole, not bugger all spring tension to make sure they are held in in my mind now either the two pistons have differnt size clip grooves or the builders simply put some clips in that are fatter than they need be and were never going to fit in the groove...
The broken peice is all that was left of the offending clip

[TZ350]

Different clip diameters, well I wasn't expecting that, they look like they were meant for different size pins.

And I wonder if there is a std imperial and metric circlip wire thats close to the same size, I hadn't thought about it before but it seems probable now.

The clips for the Kawasaki and Wiesco pistons I use in my bike are made from different size circlip wire, at a quick glance the clips look the same and they are the same diameter. But I have to be careful not to mix them up as they don't sit down properly in the grooves if I do. I hadn't thought about the reasons, I was just careful.

Very interesting and well done, looks like you have found the smoking gun.

[husaberg]

Different clip diameters, well I wasn't expecting that, they look like they were meant for different size pins.

And I wonder if there is a std imperial and metric circlip wire thats close to the same size, I hadn't thought about it before but it seems probable now.

The clips for the Kawasaki and Wiesco pistons I use in my bike are made from different size circlip wire, at a quick glance the clips look the same and they are the same diameter. But I have to be careful not to mix them up as they don't sit down properly in the grooves if I do. I hadn't thought about the reasons, I was just careful.
Very interesting and well done, looks like you have found the smoking gun.

I posted this earlier about circlips, Links below
Who knew there were so much intricacies involved with them. I sure didn't
A one dollar part that has the potential for so much Heartache.
No doubt someone probably has written a doctorate thesis on them at some stage.

http://www.britbike.com/forums/ubbth...&Number=236715
http://kb-silvolite.com/article.php?action=read&A_id=54

Re the smoking gun

the evidence has found what appears to be the weapon. But
Who fired it

Was it a mistake at the factory by placing the wrong circlips with the piston.
compounded by the fitter not recognising the problem, or not checking at fitting?

Or a mistake by the fitter using the wrong clip ?

In the pic I did note the hatch pattern looked a little odd to as it was to lack a better description asymmetrical one sided weird, It might be the angle of the pics.But it seems inconsistent.I wonder why.