Techumseh HS40 55388C for a 1970 Rupp Roadster?

M

MiataMan

New Member
#1
#1
OK, I know this engine probably isn't an exact match for a 1970 Rupp Roadster. I haven't found the serial number but the engine is black. It has the rounded cover and it has the lighting pack. I think it must have been from a Roadster II - maybe '71 - '73? Besides color, is there any difference between this engine and one for the 1970? I want to make it look right for 1970. Besides painting it silver, is there anything else I need to do to make it look like it belongs on a 1970 Roadster?

Also the exhaust port has a threaded manifold with the locking ring but it also has the 2 screw holes for a bolt on manifold. Which one is right to use for a 1970 Roadster please?

Any help would be greatly appreciated!!
 
markus

markus

Well-Known Member
#2
#2
we were just discussing this, this thread has some good info on the numbers for the Rupp engines: http://www.oldminibikes.com/forum/mini-bike-discussion/128446-rupp-roadster2-hs40-questions.html

the 88c started late 1971, so the intake and carb will be different than what 1970 used, the throttle arm will look different (but not too noticeable) and of course the ID plate will not have correct numbers, and most likely different style of stamping, If I am not mistaken the air deflector for the cylinder is slightly different too, it does not have provision for the kill wire connection on it

Internally the difference would be the Camshafts and lifters, but its just a difference in the way the compression release operated and does not affect overall running, just something they changed.

Rupp used a threaded manifold on the Roadster, in 1971 the Performance straight pipe that came on the "black widow" had a bolt on/flange header to open it up a bit, The same header could be used with the stock exhaust as well to open up that exhaust a touch.
 
Last edited:
Ajf

Ajf

#5
#5
Early rupp 71 engines still had the regular intake and diaphragm carburetor just like the 1970 models had. I'm not sure when it was changed but it was a very early thing.
 
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