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Discussion Starter · #1 · (Edited)
So I've been really really wanting to do a motorcycle engine swap for a while now. I've considered swapping a Honda Helix engine into a Ruckus frame. I've also thought about taking something like a 250cc cruiser and shoving the largest engine I could find into it. I even dabbled into seeing if I could get a scrap car engine into a bike. I want to do something silly just for fun. I think I've found out what I want to do and I figured out how to do it!

Start with a Ruckus or Ruckus clone:



Remove the engine + transmission + rear wheel combo. This will leave a nice space for you to play with. However, you won't have a swingarm since the Ruckus drive case acts as a swingarm.



I did some research into the engine mounting holes and they're actually a perfect place to mount a swingarm. Get a swingarm for an older enduro and you'll even have preexisting holes to mount the Ruckus' suspension. Something like this:



Great, now just pick up a rear wheel that's the same size as the front that is set up for a chain and brake:



And now for the heart of the operation. For this project, I'd use a 420cc Predator engine. These engines are normally reserved for minibikes, but I've seen them used on road bike projects because they're so dead simple to mount, run, and modify. Oh, and they're hilariously cheap.

A Ruck is normally a 50 and a Ruck clone a 150, this is more than enough displacement and one of these engines can be had for about $250 new on Craigslist or Facebook Marketplace. :) I've seen guys get 70-80+ mph out of these things, too.



Most of the parts on this engine can be taken apart and/or relocated, so it'll fit nicely.

Add a torque converter, connect it to the rear tyre via a chain, then enjoy one of the fastest small scooters that could probably kill you if you looked at it the wrong way.

The interesting thing about this to me is that you don't even necessarily need to go with that engine, either. With a little bit of backyard engineering you could fit any engine you can get to fit. I also had the idea to get a donor 400cc two stroke enduro and just swap the parts over...but even non-runner two stroke enduros cost a pretty penny.

As an alternative, I also thought about doing this with a 670 Predator V-Twin and a CB200 with a dead engine. Bolt in the new engine, get a torque converter, then connect to the existing rear wheel and sprocket.

Am I crazy? Yes, very much. :devil: :nerd:
 

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There's nothing wrong with crazy..

You will likely have to do some problem solving - odd things will come up like chain alignment and such. You may have to do a bit of welding here and there for oddball brackets and such. I don't think your idea is undoable, but there's always something that comes up when building or modifying.

Rather than looking for a torque converter maybe look at a friction clutch like the Coleman CT200 has. I'm pretty sure the parts are readily available at tractor supply and may be nearly a bolt on application for that engine. (My kids have a CT200 and it uses basically that same engine.)
 
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Discussion Starter · #3 ·
I looked into friction clutches and thus far I'm not sure how well it'll work. The engine produces 13bhp out of the box and have a rather large aftermarket for bumping up even more power. The good news is that either part is cheap enough and bolt on that you could try either out. :)
 
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Will this directly drive the rear wheel without a gearbox? Might want to use a variable v-belt drive like a snowmobile. That will make the most of the engine rpms.
 
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Discussion Starter · #5 ·
They come with 1" shafts, so you can slide on anything that'll fit. I have seen a couple direct drive builds with the smaller 212 Predator engines. Oooh, didn't think about a variable v-belt!
 

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Discussion Starter · #7 ·
"Variable V-belt drive" is essentially what a torque converter on a minibike/go-cart is.
Yeah, I was doing some research today on it and was like "wait, isn't that essentially like a torque converter from a minibike/scooter?" :)
 

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Wow, so it is! I had never really looked at a scooter that closely and wasn't familiar with their terminology. When you said torque converter I thought more of the thing between an engine and automatic transmission on a car.

Nothing to see here. Move along.
 

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Discussion Starter · #9 · (Edited)
Made some progress on this project! I should be able to do this without any major welding. The Ruckus has a very healthy aftermarket parts and I noticed that some of the metal floorboard mods are thick and large enough to become an engine mounting plate. Should be good enough for a "proof of concept". Then I could pair the engine to a series 40 torque converter and potentially have one of the world's fastest Ruckus type scoots to still use the stock frame.

Now I just need to get it home, rip out the stock engine, and gather my parts. The rear wheel and swingarm can come from a Chinese Honda Grom Clone. :)

Here's the little scoot as it sits right now. I removed the floorboards and skidplate to take it offroading:



 
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Discussion Starter · #10 · (Edited)
This is beginning to take shape! So while I originally planned for a 420cc Predator, I found something much better. This is a Briggs & Stratton Vanguard V-Twin engine. Originally designed for commercial and lawn applications, the DIY world bought these engines in droves for racing karts, racing mowers, golf carts, minibikes, marine, and even motorcycles. Nowadays B&S actually markets these engines for both commercial and powersports use.

It's a lot larger than the engine I planned this for (570cc v-twin as opposed to a 420cc single), however at only $150 (these things are hilariously expensive new) in running shape, that distinctive v-twin engine note, and more power (18hp vs 13hp), I see it as a win win! Bonus points for it not being a Chinese engine (so I've read, Vanguards are basically indestructible) and weighing the same as the smaller engine I was going to go with. I'll have to strip off that ginormous carb (sub Mikuni), airbox (sub pod filter), and any other bits I can relocate elsewhere, then mount it. Because of its size, I'll probably have to use a jackshaft, but that's no big deal.



Here's what these engines look like after most of the fat has been trimmed off them.

 

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Looking good. I assume you will be fashioning some kind of belt/pulley guard. You really won't believe what things look like when they get caught and tangled in those things. It ain't pretty. Your local osha at work.:grin:
 

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The Vanguard is a good engine - I used to work on a lot of them a long time ago. The good thing is they're still very well supported by B+S so you shouldn't have an issue getting parts.

This thing is going to be a monster!
 
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Discussion Starter · #13 ·
Looking good. I assume you will be fashioning some kind of belt/pulley guard. You really won't believe what things look like when they get caught and tangled in those things. It ain't pretty. Your local osha at work.:grin:
Many aftermarket torque converters come with covers so you don't become a part of your CVT. :grin:

Mounting the engine itself should be easy. I'm not sure how much the frame will be able to take all the extra grunt, so I'll want to employ my friend to strengthen it. I'll also have to figure out footpegs since there'll be an engine occupying the floorboard now.

The swingarm and rear wheel will be the hardest bits as I'll be likely be cobbling the rear end together using bits from other bikes. I'm gunning for a Honda Rebel swingarm and a Grom clone rear wheel, but have no idea if it'll actually all work together.
 

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If I remember correctly from a friend who had a Vanguard rebuilt under warranty by a dealer, his horsepower was increased by the kit that was sent because the original wasn't available at the time. This was in the beginning years for the Vanguard, I don't know if it still works that way now.
 

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I'm amazed at people that run open primary drives, belt drives with no guards, chain drives with no guards... terrifying the risk they are taking!

I've seen what 5 or 10 horsepower on a chain drive will do on a conveyor system at work when something gets stuck in the chain, I don't even want to think about what 15-50 hp engine would do to body parts caught in the drive system or dragged in by clothing!

Looking good. I assume you will be fashioning some kind of belt/pulley guard. You really won't believe what things look like when they get caught and tangled in those things. It ain't pretty. Your local osha at work.:grin:
 

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American Garage 54, oh yeah! I wait to see the results!
 

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Discussion Starter · #17 ·
I must admit I never completed this project. The guy holding onto my scooter never gave it back to me. To his credit he is literally never home, but the scooter still isn't in my possession. I will get around to doing this one day, somehow. :)
 

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Check out this young man's U-tube channel. He's a prolific builder of motorized bikes:


A guy showed up at a local vintage moto show with a Vanguard that his uncle had mounted on a Cushman Eagle. That's a LOT easier project than what you are talking about. It looked like a really fun ride, and it sounded and looked like a pocket size Big Twin. He said his uncle would ride the thing cross country on the freeway.

But none of these are crazy ideas. How about a pickup truck, powered by a 212cc predator, now that's crazy!

 
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