ETZ 125 power unit overhaul

[Jay Bee]

I spotted a con.rod kit on offer at what seemed a very reasonable price, took a chance and bought it - this provided a fresh impetus to resurrect this job (abandoned long ago).

The kit in question is a MZA item (part #15415-A-M); comparing it to the original rod I note a couple of differences :-
1/ The new rod has a small-end width of 20mm. - the old rod is 20mm. relieved either side of the bearing eye to 17mm., presumably to aid lubricant to reach the s/e needle roller bearing.
2/ The original crankpin (28mm.) is hollow - bored 12mm. throughout. The new crankpin is solid, being merely counterbored with centres.
I'm assuming these differences will also account for a variation in weight; the crankshaft is still assembled at the moment, and so I am unable to actually weigh the old parts to make a direct comparison. I certainly have no wish to put time and money into building an engine that vibrates unnaturally !

Have any of your seasoned members any knowledge/experience of these con.rod kits, and their use in these engines?
And what would be their advice regarding piston choice ?

Thanks in advance,

[arry_b]

I've fitted a few of these. They're fine, no extra vibration and no sign of early failure.

[Jay Bee]

Thanks, arry-b.
Crankshaft and con.rod assy. are now with my local engine shop for pressing apart/re-assembly.
Now to sort out the rest of the parts required..........