The Helios Project (Aprilia RS 125 Rotax 122 Biaggi Race Replica)

[declan]

@calum don’t know what your on about mate looks ready to race to me what did the piston look like

[Calum]

@declan Piston wasn't too bad. Could have used that. But I threw it in the bin. Wasn't even forged.

[declan]

@calum so maybe a stupid question but was it rebuilt badly or not rebuilt at all

[Calum]

@declan Nah man I don't think it's a stupid question.

So it's been stripped before.

There was a rusty bolt on the inside of the engine. That suggests that they just used a bolt that would normally be outside the engine on the inside. Since it was an OEM bolt.

Also, the crank is really solid.

I reckon, someone who didn't know what they were doing, rebuilt it poorly. Started it up. heard a horrendous noise, and then gave up on the idea after sinking too much money on it.

The barrel doesn't look to have been rebored. So it was likely a new barrel at the time. The piston wasn't the highest quality, but it was a decent piston.

I doubt the mains were changed, and they clearly didn't bother with the gearbox bearings. I reckon the minimal amount was done. But once it still didn't run right, they gave up on the idea.

It's funny though.

As I say, the cases are handy for my next project I'll be doing on this bike.

And all I really wanted was the kickstart. I've managed to sell some of the bits I've stripped from it on eBay. So that's some way of clawing the money back out of it.

[declan]

@calum sold bits already? Well it’s a good thing You didn’t want the engine as a whole isn’t it

[Calum]

@declan Literally just wanted the idle gear and the kickstart mate. The rest I already have.

But for this tasty little conversion I am going to do, it would be nice to have a pair of crankcases to hand

I ain't saying no more than that, you will see the results when I finish.

[Calum]

Updates are coming...

But who can guess what custom modifications I will be doing on my RS?

I won't take credit for the idea. I always wanted to do it on my DT, but just couldn't justify the price.

I then found a thread detailing a certain other bike made by Honda, whom did the exact conversion on these engines.

HM CRE 125 if you're wondering. Looks awesomse, same engine as these RS's, except they ran electronic oil inject for 50% less oil consumption. Amongst other mods.

But after not being able to find the parts I wanted, I gave up.

Then I found this build thread on a certain other website, and mans was like...yes I'm doing that.

[finnerz89]

@calum hydraulic clutch?

[Calum]

@finnerz89 Spot on mate. How did you know?

[declan]

@calum damn give me a chance lol

[Calum]

Front Mud Guards Arrived

I look forward to fitting that this weekend

[declan]

@calum that looks slick how’s the engine coming along?

[Calum]

@declan Should have some updates later in the week.

[finnerz89]

@calum I've had 2 bikes with hydraulic clutches, recognised the cylinder lol

[NINJA]

@calum I'm just curious, are the Magura Hydro clutches not compatible???

[Calum]

@ninja They're mega bucks though ain't they.

And probably not.

This is the clutch actuation on these engines

[Minia]

This is really looking sweet

[NINJA]

@calum The Magura clutches are expensive, but apart from the cheap Chinese ones on ebay, there's not a lot else too choose from. I want one on my MX for-sure, can you post a link to the thread you found detailing the hydro conversion please???

[Calum]

@ninja You won't like it, lol. It was using PhotoFuckit and all the photos are messed up.

I'll have this one done by the end of the week.

Here is how Honda did it

They've used the original clutch actuation for it.

Here is the thread.

http://www.125ccsportsbikes.com/forums/index.php?showtopic=100907

[NINJA]

@calum OK Thanks, perhaps if you have the time you could post a tutorial on how to do it and the parts needed etc. please.