The Helios Project (Aprilia RS 125 Rotax 122)



  • The Kids Are Alright and so are these bikes.

    Ever since a good friend of mine rocked up to my house on a 2001 Aprilia RS50, I knew that one day, I too would own something as cool as that. Too true this was as well, only a few months later did I take delivery of a low mileage 2007 Aprilia RS50 Spains No 1 Race Replica.

    I always wanted the bigger, 125 variant, but at the time I simply couldn't afford one. Besides that, I ended up getting a DT 125 anyway.



  • Rebooted this thread.
    But that feeling never left me, so in December 2015 I imported an RS125 into the UK.

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    Well I say an RS125, what I mean is a frame that was originally an RS125.

    So here I started, my Superteen RS 125 Road Racer build.

    It's a 2007 Spains No 1, but I will be building this bike in homage to Max Biaggi, and as such, I will be going with his Livaries. It'll be white, with touches of red.

    I will finally be building this bike from the ground up. Everything I buy, will be repaired, painted and fixed onto this frame. Starting with the swinging arm.

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    I spent hours, hand buffing the deep scratches and dents out of this rear arm.

    The rear suspension linkage was completely shot and needed overhauling.

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    Like the DT, I'm going with Candy Red for my paint colour. The photos don't do it justice. It's an eye popping colour, and when offset with the white, it goes really well.

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    I've gone with Gloss White for the contrast colour.

    The swingarm was stripped of all its bearings and bushes. Replaced with new OEM counterparts.

    I've gone with a high weave, carbon fibre rear hugger and chain guard. I'm using aluminium paddock bobbins to grant me access to maintenance when the item is pieced together. Also titanium chain adjusters.

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    The shock has been replaced with a superior YSS unit. It's fully adjustable with an internal reservoir. Sorry but I couldn't justify the price for the external reservoir ones. Especially as I only intend on using this bike a couple of times a year. Who'd have thought white would be hard to keep clean lol

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    It's better than stock, but it isn't quite SuperTeen Standard. But I want this bike on the road by the summer, so I will make some sacrafices. I can always replace this later.

    The sticky rubber that I've chosen is a pair of Diablo ROSSO II

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    These were by no means cheap, but were near enough the best that you can get for the road for these bikes. Not great in the wet, but this is totally a Blue Skies Sunny Day Bike!

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    The core components I got done in candy red. You won't see the subframe, the frame will be shown behind the fairings, and the wheels will of course be on display. So whilst it looks like a sea of red now, most of it will be hidden, and only you sneaky little devils on the forum will see its true form.

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    I manage to snag a set of clocks with a measily 1.5k miles on. Although to be fair, I really don't care for mileage.

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    I got the rear linkage fully rebuilt with new bushes and bearings and seals. All resprayed.

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    And of course, packed full of grease.

    New grommets, bushes and a respray for even the smallest of components, the fuse holder.

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    Fitted to the battery bracket.

    Which again, stripped painted and new grommets.

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    The devil is in the detail after all.

    These bikes didn't half come with some stopping power.

    Aprilia built savage four pot radial caliper for the front. With a nice dual pot rear caliper. But the pair I got needed an overhaul.

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    For this, powdercoating can damage the integrity of the brakes. No fancy colours here, these items are exposed and a damn nuisance to clean. I'm simply going for a rebuilt, Titanium split pins and brembo pads.

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    I split and rebuilt them. Clean up all the rust and muck, sprayed Matte black to allow brake dust and dirt to simply blend into the paint work. No not the best but hey, noone's perfect lol.

    Don't need these for the moment. They can stay in storage.

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    I got a set of forks, that needed a rebuild. Don't know where the photos are for this, which is a shame. But again, fully stripped and all genuine parts replaced. New Silkolene fork oil and lovely anodised aluminium red fork top caps. All ready to fit to the frame.

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    I need a few more components, then I can assemble the rolling chassis. I aim to have the rolling chassis complete February. Awaiting funds....

    At the heart of any rolling chassis is the engine. Now I know what I would like to do with this project, Rotax 257 engine transplant. But instead I'm opting for the SuperTeen Engine, Rotax 122. Very capable engines used throughout the Go-Kart Juniors. Lots of tuning parts available for these engines and very capable of that golden 33BHP mark on road fuel. I'm not saying mine will get that much power, but high twenties would be nice.

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    Here it is then.

    Looking a little worse for wear I'll admit.

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    Let us first examine barrel.

    Unlike the DTR, this engine is cylinder inducted (similar to YZ's)

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    The engine utilises Rotax's appropriately named RAVE (Rotax Adjustable Valve Exhaust)

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    Similar to Yamaha's YPVS system, the RAVE setup uses a cutaway blade to adjust the port height. It is attached to a piece of wire, which is fastened onto the chassis. The wire is pulled using a solenoid, controlled by a separate ECU.

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    The transfers on this thing are HUGE, and the exhaust benefits from two axillary ports.

    The engine relies on the Japanese to keep it lubricated

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    But once again, I intend on having this engine ported so my reliance on the pump is not needed.

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    Like the DT, the oil pump and water pump are both driven from Nylon cogs.

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    Unlike the DT however, the primary shaft and balancer shaft are also driven by nylon cogs. When this engine is shifting at 14,000 RPM making 30+ bhp, these are so prone to failure. So these will be replaced with new when the time comes.

    With all this power, the clutches are also prone to slip. So this will be uprated when the time comes also.

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    Oh dear, this engine is unfortunately scrap!

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    Unfortunately, even the other side suffered, so the crankcases were thrown in the bin. I promptly received a partial refund (enough to buy another set of cases).

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    Only the finest components were used on the rebuild. A new set of cases ordered. professionally cleaned and returned. I then went away and renewed the crank case bearings.

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    With the connecting rod having gone through the crankcases. The whole gearbox needs stripping, inspecting and rebuilding. Unfortunately there are some 8 8mm needle bearings. At £20 each I haven't justified buying them just yet. As such, the cases have been in storage ready for the crank and gearbox rebuild. I intend on rolling the chassis before building the engine. With the chassis nearing completion, it'll soon be time to resurrect the engine rebuild.



  • Nice one Calum, those wheels look terrific



  • @oldman They look better with the rubber on, better contrast between the red you see.

    I'm just waiting on spacers so I can fit it into the swingarm, which should look really nice.



  • @calum what do you think is the maximum output for a tuned rotax 122? 45 hp+?



  • @irongamer727 On race fuel with countless thousands spent on it. Maybe.

    Pump gas, I'd say 33-35. GP bikes probably just shy of 40.

    But then remember it's not all about peak power. Power is no good without torques. And this, whilst being superteen imititated, is meant for the road, where torque is so much more important.

    So, whilst I will be getting the engine ported, it'll be for road tune.



  • 45+ no chance best I saw online is 45 bhp by some crazy guy with no sense and too much money he was from Italy I think I can't find any info on it anymore shame not that anyone would do the same unless they were rich and enjoyed rebuilding it daily

    but people get 28 bhp all the time 35 has been reached by many

    she looks a stunner in bits beautiful bikes swing arms are a piece of art thank god you didn't follow the crowd and polished it I found that Continentals Conti Attack 2 feel better on rs duo to the bike being so light the angle helps in corners and there great in the wet to maybe give them a go on your next set

    looking forward to seeing progress



  • @terry-tz Hey cheers mate.

    You know what, I have been looking at builds and have been told that I should have polished it. It's nice to hear you think otherwise.

    I know keeping it clean is going to be a nightmare. But I really think it's a once or twice a year bike so it shouldn't be too hard to keep it mint.

    Yeah, also note that different dynos give different readings. I think what really matters is how it performs out on the road, for a road bike that is.



  • @calum agreed follow me so I can message you it came up with an error



  • wash every time you use most probably



  • Chipping a little more off, but money is tighter than I was expecting.

    Got some lovely bits in the post, but can't use them just yet.

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    Light weight Carbon Fibre sprocket cover. For an engine that is no where near built.

    Light weight captive wheel spacers, some 100 grams lighter than the original, well every little helps.

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    As said, forgot to grab the photos of the wheels with rubber, helps the camera pick up the actual colour of the wheels.

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    I get it won't be to everyones taste, that's fine.

    Rear linkage mated to the dog bones.

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    Counter sunk stainless steel hex head bolts for the seat lock. Won't be seen but at least I know it's fresh!
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    Battery box fitted to the brackets. Very snug fit with those new grommets.

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    All fitted to the frame using high quality titanium bolts.

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    The rolling chassis so far!

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    It's getting close to being able to wheel it into and out of the garage.



  • @calum she is becoming a beauty



  • @terry-tz Cheers mate 😃

    Long way off anything being anything yet.



  • That's better! Those wheels look tremendous, a man after my own heart! Also replace bolts and fixings with quality even when they will never been seen, will be one of a kind completed.



  • @oldman Unfortunately, one of a kind, it will not be.

    As said, these bikes are used for the Junior Moto GP racing, or were used rather (replaced with four strokes today).

    So these bikes tend to get built to an exceptionally high standard. I don't have those sorts of deep pockets, but I will do my best where I can. It'll be SuperTeen Inspired for sure 😃

    I just need the right sized circlip for the front wheel then I can put the forks and swingarm on.

    Hopefully next weekend.



  • A few little bits arrived for me today.

    I got this exact disc on my DT. It was absolutely lovely, and was £60 cheaper than what I paid for it, so I jumped at the opportunity.

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    All fitted to the wheel using Titanium bolts.

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    Genuine handle bars and switch gear arrived. Plus Titanium wheel nuts and aluminium fork top.

    Thinking of getting the handle bars painted, to contrast the white triple clamps. Then I can look to assemble it. Got some titanium handlebar bolts with these as well.

    I've also redone the swingarm bolts with titanium, which was expensive. But it feels nice to chuck the money into this vehicle as it'll be a real nice sunny ride.

    Although, I totalled the cost of the remaining parts, the price is eye watering. I think you could have bought two of these bikes brand new from Aprilia for the cost that this one is looking at. But of course, this will be far superior spec.


  • Global Moderator

    @calum only a few emojis seem to be working ⌨ 😂

    EDIT: nevermind, they are now 🤔



  • @irongamer727 0_1515853458962_2018-01-13 03.23.49.jpg

    Works fine for me.

    You have to give it a while. It uploads it to my server, which uploads it to imgur and then embeds the link. So just because it says 100 percent that just means you have uploaded it to my server



  • @calum where do you buy all of your titanium screws? Ebay presumably, but from whom?



  • @irongamer727 Company called raceti