St90 engine swap (lifan)

[slickmick]

First off, thanks for approving my request to join the forum! I'm a long time lurker and big time Honda fan. I'm currently restoring a 1973 Honda st90 in tahitian red and have another green one waiting for me to get finished so I can start on it. I am having the original engine rebuilt for the red, but I'm thinking about a lifan 125cc install for the green one. I've read just about all of the related threads and done tons of research on the internet looking for a bracket that I can use to mount a 2 hole lifan into the 3 hole mount on my st90. But, I can't seem to find a real one...

Does anyone know where I can find bracket/adapter for mounting a lifan engine into a st90?? I'm not a machinist or welder, but I would be willing to pay for a custom bracket if someone has some drawings for one and can fabricate it for me.

Thanks in advance for your help!

 

[69ST]

I seem to recall such hardware being listed on the dratv website. Look through more than just the ST90 section. They have a Lifan section, as well as performance parts section, tech info, conversions, etc.

 

[slickmick]

Thanks for the response! I have ordered tons of parts for my restore from dratv and just went back through the website and did not find anything of value for installing a lifan. I've read a few stories around the internet about guys fabricating a bracket to make it work, but I haven't found anything for sale that I could use. I probably need to work on my metalworking skills. Lol.

 

[69ST]

Here's the page I had in mind.

A rear mount adapter.
A footrest assembly adapter, plus more info.
Here's a pic of some bracketry, in an interim state of fabrication (I presume).

Don't know much about the architecture of the ST90 engine, it's outside my "wheelhouse" (no pun intended...sorta). That said, this may give you some direction as to how you might go about your proposed conversion. FWIW, I'd want to leave the frame unmolested, using custom bracketry and making any permanent mods to the engine, itself. From what I can still recall, fitting a CT90/110 engine to a CT70 frame requires relocating the lower mount to where the brake pedal pivot is located and eliminating ~.500" of interference at the upper mount. The upper mount, on that engine, can easily be trimmed to fit. Now I know that's going to be different with an ST90 frame and a Chinese engine having Z50-pattern mounts. The point is to get you thinking creatively. If the engine mounts are, say, .500" narrower than the engine mounts of the frame, it should be relatively easy to fab mount adapters from plate steel, or aluminum...plates & spacers as needed. With everything tucked inside the frame, the look would be very clean.