Any and All ST90 engine Mods?

Old Guy Too Many Bikes

Old Guy Too Many Bikes

Well-Known Member
As I remember, the ST90 engine is kinda milktoast as far as 90's go. Not a lot of power and only 3 speeds. As nica said, a carb won't do much, a little higher compression would help though. However I believe an S90 or a CL90 engine will bolt right in and wake that thing up.
 
Old Guy Too Many Bikes

Old Guy Too Many Bikes

Well-Known Member
If you want to retain the original engine, you could have the head milled to raise the compression, and check into a 90 head with bigger valves. You could also do a little porting with a grinder on the head and intake manifold. Then maybe go with a larger carb. I wouldn't go with a cam since it would make the powerband more narrow and peaky and you only have 3 speeds.
 
Shortiecar

Shortiecar

New Member
Old Guy Too Many Bikes said:
If you want to retain the original engine, you could have the head milled to raise the compression, and check into a 90 head with bigger valves. You could also do a little porting with a grinder on the head and intake manifold. Then maybe go with a larger carb. I wouldn't go with a cam since it would make the powerband more narrow and peaky and you only have 3 speeds.
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Thanks!
 
N

nica582

New Member
Just an FYI anyone who has come across the 6 bushings (swing arm,rear wheel) knows the hell it can give..I got a 22mm hole saw and pulled them right out
 
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