1969 and older rupp 3.5hp question

markus

Well-Known Member
#1
All the 1969 and older Rupps were single speed jackshafts correct? and the 5hp 2 speed models were all 3/4" clutches correct?

Also, it looks like there is room, but does anyone know if the old GEM straight shot intake setup will clear in the 1969 and older frames?

I dont see them on blackwidow, but technically the option hi-po straight pipe should work with a 3.5 as well I would imagine, I kinda thought that was one reason they never utilized the HS40 in 1968-69. Did Rupp offer and adapter/bolt on header for the 3.5's :shrug:

Thanks for any info
 

Rupp 72

Active Member
#2
In 1968 and 1969 the only bikes that came with 2 speeds were the TT500, Goat, and Roadster which all had the H50, however rupp did sell a 2 speed kit. In 1968 the two speed jackshaft was 3/4in but in 69 the two speed jackshaft was 5/8in. The 3/4 inch max torque clutch on the two speed is much harder to find than the 5/8 version on the 69 bikes.
 

markus

Well-Known Member
#3
Thanks for the info, I probably should have worded that better, I was thinking about the driver clutch on the engine and the crankshaft size the 2 speeds used as the small frame engines all seemed to come with 5/8 shafts on the chain driven rupps. Was going to put a ball bearing supported crankshaft I just got in a 1969 Rupp correct H35 engine to go along with GEM hop up parts....its a 3/4" crankshaft though not 5/8". I was setting that up to just sell after it was built as I didnt have a use for it so I was also curious about the fitment of the custom parts and if they will work with a Rupp suspension frame.

All that stuff just went out the window though...Out of the blue I just stumbled onto a 1968 C-250 roller, with tank and chainguard even that was a fair price :freakout: so I guess I will have to wait for that to get here to see if I like it or not before I use the parts on something else. That frame will have more than enough room to fit fit the carb/air cleaner and a header since its an open hardtail :thumbsup:
 
#4
Thanks for the info, I probably should have worded that better, I was thinking about the driver clutch on the engine and the crankshaft size the 2 speeds used as the small frame engines all seemed to come with 5/8 shafts on the chain driven rupps. Was going to put a ball bearing supported crankshaft I just got in a 1969 Rupp correct H35 engine to go along with GEM hop up parts....its a 3/4" crankshaft though not 5/8". I was setting that up to just sell after it was built as I didnt have a use for it so I was also curious about the fitment of the custom parts and if they will work with a Rupp suspension frame.

All that stuff just went out the window though...Out of the blue I just stumbled onto a 1968 C-250 roller, with tank and chainguard even that was a fair price :freakout: so I guess I will have to wait for that to get here to see if I like it or not before I use the parts on something else. That frame will have more than enough room to fit fit the carb/air cleaner and a header since its an open hardtail :thumbsup:
Was curious Markus. Besides the straight shot intake what other gem upgrades you have in the works? Let me know if you need any more of those intakes. Got a hs40 slant and a H25/30/35
 

markus

Well-Known Member
#5
Was curious Markus. Besides the straight shot intake what other gem upgrades you have in the works? Let me know if you need any more of those intakes. Got a hs40 slant and a H25/30/35
I got what I think is a GEM exhaust from the same seller when i got the intake, Its like a taylor spark arrestor, but its larger dia pipe and would be a more universal pipe (would fit and H and HS40 with small air cleaner or modded intake). Probably use that depending on fitment as well in the c250 frame, and probably a stack on the carb. Other than that just some internal mods I like to do, unless I find a GEM head or something!!!

I like the intakes, problem is they really need to be on a bike with a remote tank or you wont get fuel to the carb. Thats why I was thinking about the 1968/69 Rupp bikes for it. Moreso a post 1970 performance part but pretty close still :thumbsup:
 
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