Bastard Zeda 80-ish, smooth but no power.


New Member
Apr 19, 2018
Rod reads ZAE80, according to my wooden ruler it's a 38mm stroke. Started as a no-name kit bought locally. The kit ran 30mph with a 42 tooth sprocket. I took it apart and cleaned up the ports and put a little divot on the intake side skirt on the cylinder, ran 33mph till a wrist pin decided it was more important than the cylinder/piston ring mating. So I bought the zeda piston/jug kit here...

Smoothed out the ports, nothing drastic, pre-lubed the **** out of it, and after about .5gal of 16:1 it has smoothed way out, almost no vibration, sounds great. Also third ported the new piston.

Just doesn't go, I've vacuum tested it with carb spray (passed), three different size jets with all five needle positions with each one, and found a combo where it sucks less, but hasn't run like it did when it was all kit, no zeda parts (JLZeda?) Also fitted another NT carb and got frustrated and tried a dellorto clone I bought but never used. All run the same.

My hunch.... are the ports different for a 40mm stroke jug than a 38mm stroke?

This thing runs sooo smooth I hate to give up on it and get a cheaper jug to match the 38mm stroke, but by the time a bottom end to match the piston and jug I have i might as well buy the complete Zeda 80, admitting defeat (and pissing off the wife).

The piston bottoms out about 1.5mm before the transfer ports are fully open, is this normal? if I ramped the piston would that help?

I've left a lot out, so let me know what else I may have missed.

Oh, and the head is a stock angle fire that has been lapped a bit and I'm running a thin copper head gasket. Has good compression, no oil leaks anywhere.
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New Member
Mar 15, 2020
I'm having similar problem just ramped the ouston on exhaust side because I was coming nowhere near close opening fully at bdc and I lost a ton of power not sure why though ?????