Rupp Roadster2 - HS40 Questions
Maybe start off with the correct numbers found on a Rupp 1971 HS40 55388C :thumbsup:
a 55355C will be a Rupp used engine but it is non lighted, its what the Enduro/blackwidow/hustler used. It will share the same longblock and carb/intake as the Roadster2 but since its not lighted the shroud, and flywheel/ignition is different.
the 55356c seems to spec out the same as the 88c (slanted/lighted) but may have been a different color, like say silver for a speedway or something like that :shrug: The carb numbers show different, but they are both bowl carbs.
a 55358C shows as a non lighted, standard length bushing crank, standard (not slanted mount) configuration.
I dont have any photos of a 1971, just of a nicely redone 1972 55388c that I had awhile back, but it had the Dell upgrade and bolt on header/straight pipe though:
a 55355C will be a Rupp used engine but it is non lighted, its what the Enduro/blackwidow/hustler used. It will share the same longblock and carb/intake as the Roadster2 but since its not lighted the shroud, and flywheel/ignition is different.
the 55356c seems to spec out the same as the 88c (slanted/lighted) but may have been a different color, like say silver for a speedway or something like that :shrug: The carb numbers show different, but they are both bowl carbs.
a 55358C shows as a non lighted, standard length bushing crank, standard (not slanted mount) configuration.
I dont have any photos of a 1971, just of a nicely redone 1972 55388c that I had awhile back, but it had the Dell upgrade and bolt on header/straight pipe though:
Here is an Ebay link for a 71' Roadster 2 Motor. Again 55356C
Tecumseh HS40 Rupp Mini Bike Engine 4 HP Black Widow Roadster Lighting Coil | eBay
Tecumseh HS40 Rupp Mini Bike Engine 4 HP Black Widow Roadster Lighting Coil | eBay
That explains why the 56c specs out the same as the 88c. the remains of a 1971 rupp specific 88c I have here a later in the year built serial number and their changes were usually mid year. I noticed my tag is stamped type even for my 1971 where the 56c is embossed. All I saw was the carb numbers show different, and its hard anymore to find correct carbs left on even "restored" bikes to see the differences. I know they made a throttle arm change sometime around that point but I cant see them changing the engine numbers for that (the arm went for the flat tab to a humped tab that fit a barrel clamp better).
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Maybe you guys can help me figure out what the story is with the numbers on my bikes. When I bought these 2 bikes, both 1971 Roadster2's I was told they were purchased new in 71' as a pair for a brother and sister, They sat for many years and were purchased from that family estate and are in survivor condition. The only difference in the 2 bikes is, one had a float bowl carb and a slanted intake- #55356C and the other had a straight intake and a diaphragm carb- #55331C. Has anyone else come across the #55331C and does this mean it would have come with the diaphragm carb????????
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Interesting.. I bought another 71 Roadster 2 a few years ago for parts.. It had the same tag 55331C and it had a diaphragm carb which I thought was strange. An issue of mini bike guide that came out in 71' had pics of a roadster 2 with a straight intake and diaphragm carb. looks like both numbers are correct...Looks like we may have solved that mystery.
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Is the date code on the 33c earlier or later than the 56c? Blurry but looks like 1006 (the first week of January) That would make sense with the slanted intakes just coming online at that point. The specs show it with the standard intake and 631588 carb which is the one that the 1970 engines were equipped with, but with the updated cam. Lots of numbers popping up showing alot of changes, opens up a bit of options if your building a 1971 Rupp :thumbsup:
Markus, the date code on my 55331C is 1006 making it an earlier production date than the 55356C, and like Bob said you nailed it. I would like to thank both you guys for helping to answer the question I had about this for a while now.
When I get a chance I'm gonna pop the seats off both bikes to look at the Id numbers on the frame tags. Would I be correct in thinking that the bike with the motor with the earlier build date would also have a lower numerical number on the tag???
When I get a chance I'm gonna pop the seats off both bikes to look at the Id numbers on the frame tags. Would I be correct in thinking that the bike with the motor with the earlier build date would also have a lower numerical number on the tag???
That's really cool info to learn, thanks for posting that stuff up! Now I wonder if the 31c was on the 1970 model too. One of the 1970 roadsters I owned had a factory born on date of june 18th with a 55282b, which had a flyweight compression release cam. I never recorded the numbers off the others 
I'd be curious to know if the color effected the numbers or not.
I'd be curious to know if the color effected the numbers or not. 
Well I am restoring a 71 Roadster 2, it will have a 55388C (one difference might be the exhaust - screw in gear flange or two-bolt?). I think markus is correct - first the 55331C, then 55356C and by the end of the year, 55388C. I believe 88C came at the end because I have seen 72 Roadsters that had them. It's all moot for me; I'm on engine number 2 and still have no spark, but I'm hopefully making progress. My hubs came back from zinc plating and look as bad as they did before being sent out...and I still have only incorrect fenders. Oh, and the chrome plater said my headlight brackets and rear shock end caps will be done...in mid-June. So it's a good thing there appears to be some wiggle room on what can be considered correct! And finally, I have the small print on my seat cover when all indications are that the large RUPP logo is correct for 71. Doh!!!!!!!
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Just got the paint laid down on this engine the other day, Its a 55th day of 1971 55331c off a Roadster2. Its been a long road trying to get this one together for the guy, Tried my best to save what he had but it didn't work out and had to source another block and put alot more NOS parts in it than we wanted too!
getting ready to decal it. I dug this thread up hoping to find a photo of one of these to see the placement of the air cleaner service decal, But didn't see a photos of the Diaphragm carbs still on there others on here. cant remember if it was right up topside or off to the right so its more visible :shrug:
getting ready to decal it. I dug this thread up hoping to find a photo of one of these to see the placement of the air cleaner service decal, But didn't see a photos of the Diaphragm carbs still on there others on here. cant remember if it was right up topside or off to the right so its more visible :shrug:
