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Morini 500 Big End Journal

Posted: 15 Oct 2017 19:54
by andy.pig
After the oil light came on while trying to keep up with R1'S and Fireblades at Oulton Park and over revving my 500, I have stripped the motor down to assess the damage. The white metal has been taken off the shells leaving a copper layer on the underside and lightly scouring the journal. I have measured my 500 big end journal at 34.85mm at the centre. Scouring of the journal will require a regrind, can anybody tell me what the original diameter was and what oversize shells are available.

Re: Morini 500 Big End Journal

Posted: 15 Oct 2017 20:59
by morini_tom
Hi Andy,

Bad luck, but hopefully saved before too much further damage.

Big end was nominally 35mm and shells available in -0.2 and -0.4mm, so you are likely to be able to get another life out of the crank.

Shells are not in plentiful supply, see the other threads on the forum about fiat multipla shells being a possible option. Failing that then NLM or Alex luzzi are your port of call.

Well done for trying to keep up with the bigger bikes though! :)

Re: Morini 500 Big End Journal

Posted: 15 Oct 2017 21:40
by andy.pig
Thanks for replying. I think at -0.2 under 35mm for the first size and my crank already at 34.85 I will have to go to the -0.4. I will take the crank to the machine shop this week to see if the grinder thinks the scores will grind out to the 1st under before I order any shells. At least he can grind to the 1st size to see if it cleans up before grinding to the second.

Re: Morini 500 Big End Journal

Posted: 16 Oct 2017 17:00
by harrymuffin
If you do use Fiat big end shells they are in - 0.010" down to -0.040" sizes rather than the metric which go smaller in -0.007" and -0.014". If all else fails contact Coventry Metalling and Boring who would be able to recover your big end journal by submerged arc welding and regrind back to size 35mm and give you certificate to say that everything is true.

Re: Morini 500 Big End Journal

Posted: 16 Oct 2017 22:08
by andy.pig
Thanks for the advice.