aprilia af125 project 108 confusion

[mikes045]

I have recently bought a af125 and like any other af125 it has many problems... the main problems are scorn cylinder, missing radiator and hosing, rusted tank, have of the rave valve is missing. also missing a coil

the cylinder already had an oversized piston by .50 and the score what is already in the bore is about a mil deep. im quite sure its the rotax 127. the cylinder only has rotax, made in austria, and a few numbers under black paint. the engine has rave written in the casting of the cylinder.

1st question... does the 122 cylinder or the 123 cylinder fit onto the 127.
2. can i get a larger piston again and find out the ring diameter so i can re-bore the cylinder to the correct size.?
3. what coil is used for the 127 engine?
4. does anyone have any spare parts?
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Michael heape

[Kickstart]

Hi

It is a 127 engine. Neither the 122 or 123 barrels will fit. Rotax do list a replacement liner (not sure if it is still available) or I suspect PJ Engineering could make and fit one for you.

Not sure an official piston is available that is over 0.5 but a pattern one might be available.

The 127 ignition is not the same as the normal 123 (let alone the 122). It has no advance / retard setup. They are pretty rare (the very early 123 in the Aprilia cruiser used the same coil I think, but you have a lot more chance of finding a 127). The stator will not work with the blue coil from a 123 engine (the 127 coil is black). You can swap the entire ignition I think.

There are other things to watch out for. Rear tyre is a 120/80 16 and they are hard to find (it was the only bike sold in the UK that used that rear tyre). The rear shocks are not always long lived and although the fitment is the same as the later AF1 and RS125 it is quite a bit shorter than the later shocks.

Splash some pics.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Kickstart]

Hi

Just checked the parts list and Rotax DID list a 0.75 oversize piston so you do have one more official rebore size. Part number 293 658. A new liner if available is 223 155.

However you might have a delay getting one. Last time I needed an over size piston Peter Knight (Rotax guy, 0176 141 4106) said he didn't keep them in stock as little demand and had to order one in from Austria.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[mikes045]

thankyou very much for your help. i guessed the coil was going to be the hardest thing to find. i'm an engineer myself and will bore it out to 0.75. i would make the piston my self but they are very complex due to the fact that a piston isn't circular.

i will get up pictures soon. ill get the frame powder coated and the engine rebuilt and take photos as i go

again thanks for your help, mike
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Michael heape

[Kickstart]

Hi

If you need any help then shout. We have a few of these, and I do have the parts list as well.

Few bits have other sources. Indicators are shared with the early 1990s Triumphs (different stalks at the back but the stalks rarely break and can be swapped over with little effort). Think the headlight is used on the Triumph Trophy as well. The front tank rubber mounts are used on a few other Aprilias (and also used as fairing spacers on the Cagiva Freccia / Morini Dart). Tail light is used in a load of bikes (including Matchless G80). Think the suspension linkage bushes are the same as the RS125..

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing