gudgeon pin cause piston slap?

Amreet · Trackday Trickster Joined: 31 May 2010 Karma :

Hi everyone,

Got some noticeable piston slap on my MZ, only when revving in neutral, disappears when under load. I've replaced the small end bearing thinking it was that, checked con rod play and piston, the piston doesn't move from side to side in the bore, it's nice and tight, the con rod has a little side to side play but not too much, no up/down or radial movement so can't be the big end.

I didn't put in a new gudgeon pin with the bearing so could it be that the gudgeon pin itself is worn causing some movement?

Islander · World Chat Champion Joined: 05 Aug 2012 Karma :

Measuring the pin to see if it's within tolerances would be a good place to start. Wink

Amreet · Trackday Trickster Joined: 31 May 2010 Karma :

would be if I had a micrometer! or knew where to find MZ tolerances for that matter!

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

If it is a two stroke MZ then don't worry, they all sound like that.
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mattsprattuk · Super Spammer Joined: 12 Mar 2007 Karma :

Don't they have like 3 different sizes of gudgeon pin and about 6 different sizes of small end bearing?
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!! Mr. Green

Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

Amreet · Trackday Trickster Joined: 31 May 2010 Karma :

Yeah Mzs are noisy, but this one bothers me a little. Still gonna ride it like I stole it but for the £10 it could cost to fix I thought I'd look into it. I enjoy the time spannering to be honest!

As for gudgeon pin sizes, no idea! just tend to ring up Burwins tell them what I've got and they send the right thing so haven't had to worry about that much.