Aprilia 125 RS Power Valve

[GazJD]

Hey all, I am trying to take out the power valve out of my Aprilia 125RS (05 model) to give it a clean (I've been told to because I'm loosing power between 5k and 7k) I have found it and have taken the outer casing off but I'm not entirely sure how to take out the blade, I've tried pulling it out and it's jammed in there pretty good, am i doing it wrong or am i just being a pansy?

Any help would be appreciated

GazJD

[PBCup]

How are you doing it?

Haynes says the proper way is to remove the radiator and I would imagine this will make it easier.

However and dont take be suprised if some says this is wrong.

I used a metal bar and tapped it very gently with a rubber mallet and it came out no propbs at all.

BTW the vavle does not work between 5-7k the reason you have a drop in power is due to the CDI pulling back the timing around these revs.

[GazJD]

Oh ok ... well it only started doing this a few months back and i hadn't changed anything when it started doing it ... and excuse my ignorance but what is a CDI?

Thanks for the help though

GazJD

[ms51ves3]

CDI is a Capacitor Discharge Ignition. It determines when the plug(s) on an engine spark. It is electronic unlike points (which is mechanical and lives on the end of the crank) which are found on older bikes. The reason points was replaced with CDI is because CDI needs virtually no maintenance where as points need to be checked and adjusted.

[GazJD]

Thanks ... so what do i need to do to the CDI to stop it stuttering at 5k - 7k then? I may have worded the problem wrong, it's not loosing power its stuttering and basically not pulling away at all, any ideas?

[Kickstart]

Hi

CDI mod only affects from 5k to 6k, with no effect at all outside that range. It is a deliberate flat spot caused by a massive amount of ignition retard between 5000 & 6000. However the CDI unit has both that ignition map and the decent one built in, but you need to cut away a chunk of the casing to expose a bridge on the circuit board and break the bridge. This trigger the unit to use the decent ignition mapping.

As to getting the valve out, take out the battery and battery box (easy) which gives you room to easily get at it from above. The just use loads of WD40 and repeatedly push it in / pull it out. Do not hit it or use much force as it is fairly common to break the power valve blade if you do.

All the best

Keith
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[GazJD]

Thanks, I'll give the WD40 a try. I just don't understand though because I've been riding for just under a year and it's only recently started stuttering.

[Kickstart]

Hi

Heard of it happening to a few people. Only thing I can think of is that water has got into the bit of the cdi unit that has been dug out.

The powervalve opens at just under 8k, so below that it will not have much effect (unless hideously cacked up).

Suppose it is possible that the bike is suffering from wear to the attomiser tube / carb needle, but not heard of anyone finding this problem before on the RS125 (common problem on Yamahas with downdraft carbs, and also bikes fitted with Dynojet kits).

All the best

Keith
____________________
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[stirlinggaz]

hi,
have you checked to see if the pv blade is actually moving?
lift tank, remove battery & battery box, as Keith suggests. (never had to remove radiator to get blade out)
you will then see blade housing.
re-connect battery & start up, blade shoud move at around 1500rpm (cleaning cycle) & 7800rpm.
if its moving, it WILL come out-so stop being a pansy, lol. seriously they blades are made out of some sort of cheese & tin alloy invented by rotax & aprilia , so as they snap as soon as you grip em with pliers! just to screw you out of 60 quid for a new one.
as for taking the blade out, i find it easier when its warm.
as before, remove battery etc.
remove the 2 hex bolts, (i use small socket set- 1/4 inch, i think, with 5mm hex bit).
give it a good coating of wd40 or similar.
leave it for a while & just pull it straight out.
done one other day, had never been out since 2001 & took no more than an hour & that included cleaning blade with degreaser & dremel with brush attachment due to solid bits of carbon & polishing blade up.
shouldnt do any harm to clean the blade, usually makes a bit of a difference, but doubt it will be the answer to your problems.
as for cutting the CDI bridge, thoroughly recommend it.
done it 3 times (made an arse of my first attermpt, due to ignorance/stupidity) but other attempts were cheap, easy & worthwhile modifications.
cheers,
GAZ