Project Dio Z4 – fastest GET motor on the planet

Hello everyone

This is DIO Z4 one of a kind and one of the few here in Italy….but I’d rather say Europe.


Here are pictures of the ported head with a surface treatment on the rockerarms, springs and all the components of the head to reduce friction and stress. I told the HTC guys not to increase compression but dunno if they actually did it and listen to me….let’s see once everything will be ready for start how it goes.


Due to the microscopic abrasion of the surface treatment to reduce friction of the Rocker-arms it’s necessary to put bigger shimmers as you’ll see the valve lash ain’t right. Before treatment I had intake valve shimmers of 0.21mm and now it’s necessary  0.24mm. Since its hand made for those that have a Honda Zoomer or a zdio Z4 with 4 valves the two intake shimmers might be different. In my case one should be 0.235mm but I’ve already ordered 2 for 0.24mm. Better to have more and than reduce it manually than less!


In any case even with older shimmers and wrong valve lash the engine started smoothly and had a very good acceleration compared to the stock engine….but it made some noise while idling…-t did sound like an idling DUCATI…which turned many heads at the traffic lights hahahah! Lol!


Following pictures of the various pics of the rebuilding process.



since this engine (at least the 4valve version) runs pretty hot I removed the thermostat. I’ve noticed it takes just a minute to reach 50degree C. Running temperature as you can see from the following video it’s fairly low. You can touch the radiator without getting burned. For tuned engine, at least up to the level I reached I would say it works as a mod.

Even at full throttle temperature never reaches 80 degree… in the video I was running slow because it was just rebuilt and it’s recommended to go slow for few miles.


The following mod is a performance exhaust and here we see the Polini for raced turned into a MIVV like exhaust… pretty sick looking!!! Sounds good as well!

66.72kmh top speed with stock muffler and Kitaco variator with 4gr rollers. 
64.01kmh top speed with the Polini exhaust and Kitaco variator and 4gr rollers



…The original muffler is more performing than the Polini with this configuration. Just the sound it’s better



There’s not much to say much about it. Looks Fantastic but with stock light bulbs it doesn’t let the light go through…may be if you put Xenon or led light it might work and go through it. I removed it cos wasn’t safe.



lightweight flywheel+kitaco variator+Polini exhaust+4gr rollers+Kitaco hybrid cdi: 78kmh

lightweight flywheel+kitaco variator+Polini exhaust+4gr rollers+Kitaco hybrid cdi+tuck: 84kmh

pimped engine block+lightweight flywheel+kitaco variator with 4gr rollers: 52kmh

pimped engine block+lightweight flywheel+kitaco variator with 4gr rollers+tuck+gy6 clutch conversion kit: 58kmh

pimped engine block+lightweight flywheel+kitaco variator+Polini exhaust with 5.5gr rollers+gy6 clutch conversion kit+tuck: 64kmh

ps. all the above mentioned where tested with valve lash not even checked!


pimped engine block+lightweight flywheel+kitaco variator+Polini exhaust+5.5gr rollers+tuck+gy6 clutch conversion kit+PERFECT valve lash clearance: TO BE TESTED!…I suppose it will be around 70kmh


pimped engine block+lightweight flywheel+kitaco variator+Polini exhaust+5.5gr rollers+Kitaco iMAP set on map n.3+tuck+PERFECT valve lash clearance+gy6 clutch conversion kit+a new belt: TO BE TESTED!…most probably 90kmh or 55mph!

with this new worked engine block seems that there’s too much fuel…so probably I’ll test it with a cone filter as well.

The ultimate goal is 62mph or 100kmh with the kitako or metropolitan gears.




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