yup... the jug is still in great shape... a broken fin on the outside but the bore on this one is imaculate... I've just throwing out conservative numbers until I find out more about this engine... Just bought it a few months back and set it aside until I got my shop set up... still got a lot going on there too since I haven't hired any help yet. But I'm sure it can make the big power by adding more rpm so the torque shouldn't be too strong for the cvt belt... If I can get upwards of 10hp just by upgrading the intake and carb that's a really sweet deal.
The engine costed me $430 after shipping costs. The big bore kit is only $100 and if I remember right, the intake and reed upgrade isn't very expensive either. the link at treatland is messed up right now but here's the direct link to the engine's description...
https://www.treatland.tv/franco-mor...start-eng-p/franco-morini-complete-engine.htm
Here's the big bore kit that bolts up to it...
https://www.treatland.tv/malossi-45...BK-MORINI-p/cvf-mbk-ew-malossi-kit-314195.htm
Kinda hard to pass up this deal so mine will most likely get this before I get a chance to install it in anything... Just gonna have to build a really strong frame, drive train, and rear wheel setup if it has the potential you say it can do when upgraded... Here's the link to all the upgrade parts treatland has that fit this engine...
http://www.treatland.tv/SearchResults.asp?Search=MBK+CVF+EW+50+av14 May need to do something different for a better reed unless you got any links that wold help in that area.
How are the ports on the 5.8? is it a 4 port with a boost port on the intake? The 50cc jug that's on it has very similar ports to the 70cc cylinder in the pics at treatland... I did notice the ports were pretty well sized for the engine when I pulled the head after I got it. If the 5.8hp version has the same type ports then it most likely could make closer to 10 hp or more just by letting it breathe and rev up more. I'm assuming this thing can rev pretty high once it can breathe, and these may have been detuned to 3.9 hp for the type of bike it was in and the age group of the riders the bike was built for etc.
I'm starting to like this engine a LOT better already and may shift my thinking on what to build with it... this May just be a good cantidate for making a Boxxer type bike to put it in after all

... May be paying harbor freight another visit to get some tube bending equipment real soon... now I Really wanna make a killer frame to put this engine into...
