Honda s90

YellowBeetleSB

YellowBeetleSB

Member
Does anyone know of a forum like this but for the Honda s90? I'm trying to find resources for parts, and other people doing restorations on these bikes. Thanks very much.
 
dratv.com has some parts for S90s. And the engines for the ST90s are esentially the same except for the transmission (st90 is 3 speed) and the camshaft.
 
I think the standard Dr ATV cam is stock. But you can buy a longer duration but only slightly higher lift cam. I have one (won in a raffle) and might someday tell you how it works.

Rick
 
Someone on here did a mix and match of S90 and ST90 parts and found that the stock S90 cam was hotter than the dratv hot cam
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That someone was me. The best way to tell is to mic both of them, which I did. The S90 cam had a very tiny extra lift. It also had a long duration like the DR ATV cam. This is the way I see it, the DR ATV cam is an aftermarket version of the S90 cam. The quality of the S90 cam seemed to be higher. The circular part of the cam lobe was smaller on the S90 cam then on the DR ATV cam. The DR ATV cam appeared bigger, but the circular part of the lobe was just bigger. The difference between the circular part and the eccentric part is the actual lift, and the S90 cam just beat the other.

Other things. The ST90 tranny is crap. The S90 is good. The ST90 has an auto clutch, where the S90 is fully manual. So the clutch side engine cover is different. The splines used in the shafts are different depending apon the year of the S90. later ones have no separate circular clutch cover on the clutch side engine housing and the same splines as the ST90. Earlier ones do not. Really early S90's have a lighter piston, a separate oil strainer cover on the bottom and an aluminum cylinder with a sleeve. I don't really know when all of these changes too place.

I've never used this place, but I found it one day: Tena Vintage Shop

Lots of parts are shared between different 90's. The engine is the same basic design.

For example: My ST90 engine has mostly S90 guts (cam, tranny, clutch). I got another piece to adapt my ST90 splines to the old style S90 splines. It was a later style clutch drive plate that was listed for an ATC90. It wasn't really from an ATC, but I recognized it on ebay. Here's the thread on my bike: http://lilhonda.com/webboard/f14/st90-college-project-bike-11291/

Have fun!
 
Thats right! Sorry, you slipped my mind joe.
I dont know how long they made S90s for, but the lighter piston/aluminum cylinder/seperate oil strainer were last on 1964/65 models. They also had an oil line going directly behind the clutch for better lubrication and a very desirable offset aluminum intake. My S90 engine is from one of these early ones, unfortunately I do not have the offset intake though, which is why it hasnt sold yet.
 
titan joe said:
That someone was me.

For example: My ST90 engine has mostly S90 guts (cam, tranny, clutch). I got another piece to adapt my ST90 splines to the old style S90 splines. It was a later style clutch drive plate that was listed for an ATC90. It wasn't really from an ATC, but I recognized it on ebay. Here's the thread on my bike: http://lilhonda.com/webboard/f14/st90-college-project-bike-11291/

Have fun!
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T-Joe - I too have the guts of the Honda S90 (actually CL90 but nearly same thing). I however don't have a rack. Where did you buy your CT70 rack? It looks a bit small.... Would you be able to carry a case of beer on it?
 
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