1970 rupp sprint needs help looking for ideas

So I have a 1970 rupp sprint. I have the frame , wheels tires , bars throttle not much else other than a vintage Briggs and Stratton engine

I need a cross shaft and torque converter etc. But I dint want to spend a lot of money on this, I want it work as cheaply as possible so my kids can play with it and o can use it as a pit bike for my race cars.

Maybe not a torque converter maybe just a centrifugal
Clutch whatever the best way to get it running cheap is what I’d like to do.


Thanks Manchester I thought that might be possible. Wasn’t sure though that’ll work to get me going and later I’ll install the parts for the x shaft when I know everything else is worthy

Question : does anyone know what size chain these used, Link size?

If I were to just invest in a jack shaft will this work on a 70 it’s listed for 68-69 assuming there’s a difference or they’d have listed it that way if it fit. http://blackwidowmotorsports.net/_13132j_2_speed_jackshaft_kit_1968_69.html

Fits under the category of you dont know what you dont know . This is not a restoration project too far gone for that just want a fun old school bike to ride around in the pits and let my kid have fun with it.
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Take a look at my pics tel. Me if that looks like a sprint? It looks like it had the tube for a jack shaft does yours have that? Thank you for the info on the chain. I appreciate the help any chance you have the length on that chain as well? Just to give me a starting point on what size to order.
I can measure if you don’t it’s Ok but makes it easy to have the inf from someone who knows for sure.
thanks again for responding

Wondering is that tube is where you have the plugs in yours are those plugs available still or aftermarket?


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Well-Known Member
Not sure about where you live, but around here, you could probably sell that for about enough to buy a new Coleman CT100.
No hassles, no modifications to fit that big engine, no chasing parts. I am in North Carolina. Might consider a trade for a running bike.
Up in CT so not exactly close by.
This is the same
Mini bike o had as a kid.
Mine didn’t have a jack shaft either but I always thought it was just rigged up that way.
but yeah I probably could sell it easy enough to cover a new one that running.
I’d consider that as I have plenty of other projects that need my attention. Speed Boats and race cars etc . Just can’t keep up these days. Getting old I guess.
it’s worth putting some money into. You have a lot there. Just a FYI. There is a swap meet on Sunday May 6 at Rentscher Field in East Hartford. It’s an Automotive type meet but there is always small engines, go kart mini bike stuff too. You could probably fine a nice vintage Tecumseh engine there, I found one last year on a leaf blower
Thanks for the heads up on the swap meet maybe I’ll check it out. Haven’t been to one in years used to go to Stafford all the time. Heard they are pretty much like Amazon junk these days in comparison but never know I guess. Need some old vintage Lakewood square tube traction bars too if anyone happens to run across any. 69 camaro firebird. .

many anyone ever needs any alluminum done I have a vapor blaster and do a lot of car parts comes out like new . Could be helpful w anything alluminum on mini bikes as well . Not that these have a lot of alluminum in them . But I’ll probably do the wheels at some point I’ll post the results so you guys can see the difference .
Ok so I have it all mocked up w a 6hp Honda that I had on an old pressure washer. Engine actually fit really well in this little bike and should be very reliable . (I know it’s not a tecumpseh) but it’s what I had . Git the rear wheel figured out and mounted (though it was missing some parts but it’s working well . My question is

does the 70 roadster seat fit this sprint? They have a nice 70 road set seat cover on Amazon not super cheap but will like nice.
Amolace ti get pre cut seat foam?