Rieju Marathon AC SM 125 Project Build

Rieju is a Spanish motorcycle manufacturer (Now owned by Piaggio of Italy) of small displacement engine bikes mostly in the off road category however they also have some road only bikes too.

I had liked their bikes for some time and always wanted a small cc trail bike to go rip some trails when I felt the need, but also wanted to get into a challenging project build again.

So I set about finding the cheapest Rieju I could find. One that was a little worse for wear and tear but I knew could be resurrected to some form of road and trail capability.

After scouring the local ads and online sources, I eventually found a Rieju Marathon 125 Air Cooled Supermotard on Facebook Marketplace which I was able to strike a deal on. Although the price was acceptable for me at the time, in reality when I picked up the bike it would require a lot more work than I had originally assumed, so you might say the £500 I paid was too much considering the amount of money that it would take to make it road going again.

So this page will provide links to the playlist of videos of the full build and final review as well as photos and information resources too. I will add a simple spreadsheet at the end to give you an idea of how much the total project cost, but be under no illusion…these are cheap bikes to buy in the first instance, so the value of the bike would probably be less than the money spent on it overall…as most projects are!

Rieju Marathon AC SM 125 Project Build Playlist

Workshop & Owners Manuals

Engine Service Manual 125 CBD AC

Marathon 125 Chassis Manual 2019

Marathon 125 AC Euro 4 Owners Manual

MRT 125 AC Euro 4 Owners Manual

Marathon 125 Owners Manual

Marathon 125 2012 – 2015 Parts Catalogue

Marathon 125 2016 Parts Catalogue

Rieju Marathon AC SM 125 Torque Figures

Other Rieju Motorcycle Owners & Workshop Manuals

Yamaha WRLC 125 Engine Workshop Manual

Century 125 i.e E4 Engine Workshop Manual

Motor AM6 Workshop Manual

Marathon 125 Chassis Workshop Manual


Marathon 125 AC Owner Manual

Marathon 125 LC 2015 Owner-Manual

Marathon 125 Cross Workshop Manual

Motor CBD 125cc Air Cooled Engine Workshop Manual (Spanish)

Engine 50 Engine Workshop Manual

MRT 50 Chassis Workshop Manual

MRX-SMX 125 Electric System Engine Workshop Manual

MRX-SMX 50 Chassis Workshop Manual (Spanish)

RS2 125 Naked Electric System Engine Workshop Manual

Marathon 125 PRO Euro 4 Owners Manual

MRT 50 Owners Manual

Strada 125 ie Owners Manual

RR-Spike 50 Engine Workshop Manual

RS2 50 Chassis Workshop Manual

RS2 125 Electric System Engine Workshop Manual

RS3 125 Engine Workshop Manual

Strada 124ie E4 Engine Workshop Manual

Tango 250 Chassis Workshop Manual

Tango 125 Euro 4 Owners Manual

Tango 125 Owners Manual

Tango 125 Chassis Workshop Manual