Ru-p Roadster 2 engine replacement

#1
I have a 1971 Rupp Roadster 2 with a tired engine. I am considering replacing it with a new motor. From what I understand, a Predator 212cc is the way to go? I see Harbor Freight has them for under $200. How much of the existing items can I reuse And what else would I need? Thanks!
 

toomanytoys

Well-Known Member
#2
I had one temporarily in a rupp black widow. If I remember correctly i was able to use everything factory had on there.

Although you need to do a cone filter intake and you'll need to make a header. Remove the fuel tank and use the frame mounted tank like factory. It works great overall.

Personally I feel like finding a good hs40 or hs50 and put it in rather than a predator... I had the predator in there just to do it. Took it out and put a NOS HS40 to keep that factory look.
 

mustangfrank

Well-Known Member
#3
I have a 1971 Rupp Roadster 2 with a tired engine. I am considering replacing it with a new motor. From what I understand, a Predator 212cc is the way to go? I see Harbor Freight has them for under $200. How much of the existing items can I reuse And what else would I need? Thanks!
A Predator is ONE way to go...just looks really wrong in a vintage slant mount frame. What's in it now, original engine?

Post some pics of your Rupp.
 
#4
I had one temporarily in a rupp black widow. If I remember correctly i was able to use everything factory had on there.

Although you need to do a cone filter intake and you'll need to make a header. Remove the fuel tank and use the frame mounted tank like factory. It works great overall.

Personally I feel like finding a good hs40 or hs50 and put it in rather than a predator... I had the predator in there just to do it. Took it out and put a NOS HS40 to keep that factory look.
Thanks for the response on your experience. I am not the most experienced mechanic so this seems a little intimidating to me.

Are NOS HS40 motors hard to find? Definitely would reuse the original tank as it looks way better than the predator motor mounted tank. Did Black Widow make a header? I seem to recall…
 
#5
A Predator is ONE way to go...just looks really wrong in a vintage slant mount frame. What's in it now, original engine?

Post some pics of your Rupp.
Original engine is in it currently. What‘s another option? I am looking for something easy for me to do with my level of (in)experience and up the performance a bit. Thanks!
 

toomanytoys

Well-Known Member
#7
Thanks for the response on your experience. I am not the most experienced mechanic so this seems a little intimidating to me.

Are NOS HS40 motors hard to find? Definitely would reuse the original tank as it looks way better than the predator motor mounted tank. Did Black Widow make a header? I seem to recall…
I made my own header.

You can find anything if you look enough. But 10 years ago no one gave a crap about minibike stuff. I picked up a nos 1970s HS40 for 75 bucks. Never started in the original shipping box.

That bike is pretty nice to put a darn predator in. But I'm a purist most of the time.m.
 
#8
I made my own header.

You can find anything if you look enough. But 10 years ago no one gave a crap about minibike stuff. I picked up a nos 1970s HS40 for 75 bucks. Never started in the original shipping box.

That bike is pretty nice to put a darn predator in. But I'm a purist most of the time.m.

I am hoping the motor can be rebuilt. Was told that the thrust bearing is bad among other items. Not even sure where the thrust bearing is or what it does! It may just motivate me to clean out the garage and work on it myself…
 

mustangfrank

Well-Known Member
#9
Original engine is in it currently. What‘s another option? I am looking for something easy for me to do with my level of (in)experience and up the performance a bit. Thanks!
There are a few guys that rebuild/restore them properly (NOT small engine shops, don't waste your time). A Tecumseh flathead from a snowblower donor with your tins installed is a cheap(ish) way to run it, look right and preserve the original engine. A 5hp HS50 looks identical to your 4hp HS40 externally, you'll just have to research the swap because of the longer Rupp specific PTO length your engine has now.

Bike looks nice, It'd be a shame to put a Chinese engine in it IMHO.

Black Friday is coming, for less than a proper, original Rupp HS40 sells for outright you can buy a Coleman minibike and go ride instantly if you don't want to fix your vintage minibike.
 
#10
There are a few guys that rebuild/restore them properly (NOT small engine shops, don't waste your time). A Tecumseh flathead from a snowblower donor with your tins installed is a cheap(ish) way to run it, look right and preserve the original engine. A 5hp HS50 looks identical to your 4hp HS40 externally, you'll just have to research the swap because of the longer Rupp specific PTO length your engine has now.

Bike looks nice, It'd be a shame to put a Chinese engine in it IMHO.

Black Friday is coming, for less than a proper, original Rupp HS40 sells for outright you can buy a Coleman minibike and go ride instantly if you don't want to fix your vintage minibike.
I want to fix this bike. vintage for me. I waited my entire life to get one of these Rupp Roadster 2 mini bikes. Couldn’t afford one when I was a kid so now is my time! Got a suggestion on who could rebuild the motor for me in the correct way?


I am not saying I wouldn’t still get a modern one…
 

mustangfrank

Well-Known Member
#11
I want to fix this bike. vintage for me. I waited my entire life to get one of these Rupp Roadster 2 mini bikes. Couldn’t afford one when I was a kid so now is my time! Got a suggestion on who could rebuild the motor for me in the correct way?


I am not saying I wouldn’t still get a modern one…
I haven't dealt with any directly so I won't recommend one over another but post a Want Ad on here and see what responses you get, you can always look at past posts and history to "vet" one.
 
#12
I am not saying I wouldn’t still get a modern one…
It's over, your done...Before you know it you'll have 10 in your garage.
Seriously if you want an easy to start, pretty low maintenance motor there is nothing wrong with the predators. But definitely keep that motor and have it fixed to your liking. I really prefer the look of the old tecumseh.
 

toomanytoys

Well-Known Member
#13
I was all in on vintage but these new coleman bikes are awesome. You never feel guilty doing anything to them.

I have a 12x20 shed full of vintage bikes but only ride my coleman bikes. They are all amazing! BT200X and CT200U are the best in my opinion.
 
#16
Thanks for the link. Got a lead on an old snowblower about n hour from home. HS50 engine that supposedly runs well. $80.you said the drive shaft is longer and or tapered compared to the HS40?
Rupps usually have a longer crankshaft on the PTO side. The pinrepair website has a ton of info on converting snowblower engines over. I would never put a chinese OHV engine in a vintage minibike but lots of people do it.
 
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