Noob w/basket '73 ST90 starting to collect info

[dieselkid]

Hey everyone-
Bought a basket case but complete(ish) bright green ST90 w/an engine that turns freely. Wiring is a mess, signals are busted, cables/tires will need replacing, etc etc etc...
Even so, I'm determined to get this thing running. I don't care abt originality, only that it's legal and runs well. I may wish that I bought a CT70 in the end b/c of all of the easily acquired aftermarket parts, engines, and tires but I have this thing and want to know what I'm up against.
I've scanned the ST90 threads and now know these are not rare, per se, but are rare enough to not have a lot of info floating around out there, nor the interchangability the other models enjoy. Too bad, really, as I bought it b/c of it's slightly larger size. I'm only 6' 170 but I like the 14" wheels and slightly taller riding height. I've downloaded the owners manual (thank you!) and hope to find a shop manual. Any tips would be great. I'll be asking more specific questions once I get cracking. Thanks, everyone-

Matt

[bjatwood]

Welcome aboard Dieselkid!
A good place to start looking for info and parts is here ST90_PARTS CLICK_ON_BIKE
They are a very good source for anything and everything from tools to parts.
Do you have any pics of the bike you can post here for us to see?
Most everyone on this site enjoys following rebuilds/restorations so ask plenty of questions and post lots of pics. There is ALOT of knowledge on this webboard about these little HONDA'S.


BJ

[dieselkid]

so i took out the motor, which is a three bolt configuration. i've read that there are other three bolt motors but the configuration is different. i'll try doing another search to find out for certain what engines (Lifan or OEM) will fit but i'm kind of hoping the Chinese engine will work, only b/c the one i just took off may not be worth rebuilding. besides, i'm used to a clutch and would love to have a 4 speed manual. i see these readily available from several sources starting in the high $200 price range. Any ideas on which kind i should look into? i'd probably start with the 110cc and up, but not stock. Thanks!

[on_ice]

I will be following this thread! I was in a similar situation (but not as bad it seems like) with my ST90, and ended up rebuilding it with a kit off ebay.

What kind of diesel do you drive?

[dieselkid]

I'd love to know how the rebuild turned out! I'm definitely going to tear this one down and check the condition of the internals. I've already removed the engine from the frame, not to mention the forks, wiring (which I had to cut in several places), fenders, you name it. I'm not really interested in keeping it stock- far from it. I'm probably going to half-rat it out; bob the rear fender, put on a tire-hugging front (plastic?), lose the OEM air filter for a foam style, put on small blinkers, etc. Even the seat is nothing but a pan- I'll have to fab that.
Overall, the project is simply to have a scoot-type bike that isn't the ubiquitous Vespa or Honda Elite, Yamaha, etc. I love things that are a little off the beaten path and want to ride this around town as a commuter. And since the thing was in such poor condition to begin with, I won't mind ditching the original (and knackered) parts for cheaper aftermarket stuff. It won't be pretty- it'll just be my beater scooter.
As far as my diesel? I'm sad to say I sold my 1981 Rabbit Caddy a year ago and really wish I hadn't. There's a very good chance I'll get my friend's BMW 524TD next year(!) which is also rare... making it difficult to find parts/service. At any rate, my only tattoo is of a Bosch diesel injector pump from a NA VW 1.5/1.6 on the inside of my bicep. I just love diesel technology and have for years.
I hope more ST90 folks can help me out with any info. And get back to me on your rebuild- I'd love to know what your experience was like. I've thought about finding an S90 4 speed engine and swapping it as it DOES have the same bolt pattern. Thanks!!

[motodevo]

hey is this link any helpCT90_ENGINE_SWAP PARTS_NEEDED SOME_INSTRUCTIONS

[dieselkid]

Thanks anyways, motodevo, but the bolt pattens on the engine are different. If you look closely on the top-most engine mounting hole, you'll see only one. The ST90 and S90 both have two mounting holes: one in the center of the Honda emblem and the other just above the front sprocket. The most common (fits Trail 50, CT70, CT90, etc) is like the one in the link you sent. Maybe I WILL eventually get a CT70 and bump it to a 110cc with one of the Lifans, but for now I hope to get this thing running. Thanks again-

Matt

[on_ice]

From what I hear the CT110 engines will bolt into our bikes. Its hard to find info though so I kind of gave up. My rebuild is ok, first bike rebuild and i wish i did some other things but hey it runs after 15 years of not running. It smokes a bit and idles funny but I attribute some of that because it has a CT70 carb with SOME st90 jets in it.....still trying to buy a ST90 on on ebay for cheap. Other then that it runs pretty good

<<<<<<-----------Drives a VW Jetta TDI, loving the 700 miles per tank!

[motodevo]

ct110 will bolt right in, i have a st90 and a ct110 engine sitting side by side and they're identical

[dieselkid]

motodevo-
the engines do look identical sitting next to one another, but the bolt pattern IS different. on the ST90 and S90, right above the is the forwad engine mount. right above the front sprocket is the second. the third is irrelevant as it's the top two that seal the deal (in terms of just identifying compatibility).
i immediately looked up pics of CT110 engines and sure enough, they're the same bolt pattern as the 50/CT70, etc. i'll try and upload a few pics of mine and show you what i'm working with. i may just have to get the CT70 and get the CT110 engine. thanks again