gudgeon destruction

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Eibar
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Fri Mar 18, 2011 7:13 pm

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Took the above pin with small end and crank to local trusted engineering firm who deal primarily with rebores, crank rebuilds, piston development etc etc.

I enquired what could have caused such advanced destruction of the central section of the pin over a 2000 mile period. Id already done 15k on my mugello and purchased a new gudgeon and small end from cam lam together with renewing the rings then this happened. Now I have my own dyno b4 you think it was running poorly and i keep my motors in good order.

Thats a full 0.5mm of wear in a short spell of time and compression,squish,timing etc have all been addressed fully.

Now for the odd bit the guy in the company I went to (no names mentioned) said "where you running rock oil" now I have always run synthesis 2 injector. When I said yes to his question he merely raised his brow in a 1950's bicycle repair man stylee.

Now this may all be speculation and cadswallop but I thought I'd share it with as i'd heard a similar story a few years from a very well respected tuner but I ignored it as I just thought he was trying to boost sales on his putoline contract.

All the best , Eibar
potato

J1MS
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Fri Mar 18, 2011 7:19 pm

Two questions.

At what percentage was the rock oil run ??

And do you ever visit Readspeeds ??

Eibar
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Fri Mar 18, 2011 7:25 pm

3% and Yes.

I know you favour 4% don't ya !

wait till the ethanol level in petrol goes up to 20% legally and regular 2 stroke oils break down.
potato

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sean brady scooters
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Fri Mar 18, 2011 7:29 pm

it could of course just be a bad piccy but it looks to me that things just wernt centralised...the wear looks offset to one side ..
could this be a matter of a twisted con rod or just a little end bearing that was not wide enough ..
Sean Brady Scooters - 01765 690 698

J1MS
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Fri Mar 18, 2011 7:34 pm

Eibar wrote:3% and Yes.

I know you favour 4% don't ya !

wait till the ethanol level in petrol goes up to 20% legally and regular 2 stroke oils break down.
Yes 4%, but only because I know a little about what ester based oils are and how they lubricate.

But I'm Still doing a bit of reading for the Ethanol content and it's effect.

But I think it's going to have repercussions for our two stroke engines and the oils we choose, but I'm sure the oil companies will know this and address the potential problems.

Iwas wondering if the pin had been hardened properly. You could do a hardness test if you have access to a vickers or similar test rig.

Eibar
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Fri Mar 18, 2011 7:48 pm

It could well have been a dodgy pin ( no facilities to test )

Crank and small end both inspected and were fine. I specifically got the crank checked over following the problem.

On a side note .http://www.jawaczownersclub.co.uk/techn ... vice13.htm
potato

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