2004 Aprilia MX125 powervalve?

[daz125]

i've not had my bike for long and it is totally standard, would it come as standard fitted with a powervalve (i hear some other makes of bikes have them fitted but where they don't work) or is it an extra i would need to buy. i'm going to buy an Arrow exhaust for it and i'm unsure as to whether theres a powervalve fitted already

basically i would like to know how to derestrict it, is it just the exhaust i need or will i need extras to get it pulling well

i know its a n00b question but hey, i'm a n00b

[Kickstart]

Hi

It might have the power valve. Look at the exhaust where it joins the engine. On the barrel just above that look for a bolt on housing (2 bolts) with a cable coming off (pointing forward and up at about 45 degrees). If that is there then it has a power valve fitted.

All the best

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

[daz125]

it does have the housing

does that mean its got a power valve fitted and i need to do something to it to get it to work (other than swapping the exhaust)

thanks for your help

[veze]

i imagine its got the rotax 122 or 123 engine, same as the rs. the have an exhaust valve know as a R.A.V.E valve which stands for Rotax, Adjustable, Valve, Exhaust or sumthing like that.
Have a look at the cable coming of it, and try and follow it back, it should locate in a solenoid, which will look like a small metal cylinder. that solenoid will pull that cable which makes the power valve slide out at precise engine speeds, (in this case 8000rpm). it operates at 1200 revs, then closes then opens again at 8000rpm. have a look at the solenoid while you rev the engine slowly and see if it moves, if it does, then its operating fine. now, if the solenoid is working fine, it could mean that you power valve is upside down. the power valve blade itself has a taper on it, this taper should be placed in so the tapered part of the blade is facing down. let me know how you get on matey.
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tlm50,mt5,sr50. rs125 extrema, cbr 400rr nc29 suzuki gs500e.Honda cbx250 rs . FJ1200 .fz6,fjr1300

[BenR]

As far as I know the MXs are the 122 engine, the 123s haven't been around since 1998. You only need to derestrict the CDI. Guide here -> https://www.125ccsportsbikes.com/forums//index.php?showtopic=31334&mode=threaded
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Current bikes: suzuki RG125UN wolf. Yamaha MT-07

[daz125]

thanks guys, i'm beginning to understand now, i'll keep you informed

[Kickstart]

Hi

The cdi does not restrict the top end power. It does cause a deliberate flat spot (in the mid range between 4750 and 6000rpm (with about 20 degrees of ignition retard between 5000rpm and 5750rpm), probably to get the bike through some noise or emissions tests but the "derestricting" of the cdi has no effect at all outside that rev range.

As said above, check the cable is there and that the operating solonoid is there (although it might be there and disconnected). Also worth checking that the valve isn't sticking.

All the best

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

[rich16]

i think ive found the solenoid but can only feel it not see it? its right under the tank isnt it?

[ash-2009]

does it not kick in so far through its gears and go balistic??

where u from dazz?

[rich16]

what do u do if the solanoid isnt working? i assume u can check if the cable is moving at the powervalve and the solenoid. coz its a bit too hard to see the cable into the solenoid. ive tried looking at both, defo isnt moving. just had the valve out and its a bit shitty, but tapered end is facing down so its the right way round..