aprillia rs125 problem ???

[sunbear]

hey there

my first post so treat me good bitches.

brought an aprilia rs125 replica a couple of weeks ago. has been bore out to 160cc but doesnt seem to go as quickly as it should. not even as quick as my old tdr125!!!! its got a scorpian exhaust, k&n filter and even an alloy frame, but just isnt a patch on my old only slighly destricted mito. any ideas?

cheers

[Kickstart]

Hi

Performance as standard should be within a gnats of the Mito (they are so close that what you had for breakfast will have about the same difference).

The big bore kits often do not give that much extra top end power, mainly power in the low and mid range.

Realistic top speed should be about 100mph, with quite a bit more indicated (based on one with the 34mm carb). On my early model one (large white tacho) I have had an indicated 115mph (185kmh) and 100mph is quite easy to get sitting upright (remember these are indicated speeds, so bear little resemblence to reality, I really should get a GPS unit).

The K&N will only do a tiny amount of good, and only if jetted appropriatly. No idea about the Scorpian exhaust.

First thing to try is a compression check and to check that the power valve is working (and also is the right way up, seen dealers get this wrong). The power valves do tend to stick if the bike has been run at low speed for quite a while (such as running in a new piston).

All the best

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

[sunbear]

cheers mate. probably guess im not too hot on the technical side so wont beat around the bush . had a thought it might be the power valve but aint got a clue where im looking

[killa]

Welcome to the forum mate.
Go to the workshop section of the forum for manual stuff, have a look see for the power valve location.
All those mods you have done would be great if jetted and carb’d up right, IMO taking the RS to that level is mental! Lol
Good luck!
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Cleverly disguised as a responsible adult.
Bike:- Yamaha TRX850 | Killas Biking History | Killas Gaming History | Killas autmotive history

[sunbear]

Cheers

[Kickstart]

Hi

Lift the tank up and under the battery above the exhaust you will find the power valve. It has a cable going to it. The housing for the power valve has a rubber cover over it where the cable connects. Peel the cover back and start the engine. You should see the cable (and the very end of the power valve) moving as you rev the engine. The valve should be open below 2500rpm, then closed from there to ~8000rpm, after which it opens again.

The exact revs at this stage do not matter too much, just check it is opening and closing.

Also, the bit of the power valve that you can see moving should have the cable connected to it. The end of the cable has a bobble on it which goes into the power valve. From the position you are looking at it the bobble should not be visable. If it is then the valve is in upside down.

All the best

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

[sunbear]

Nice one mate, will give it a look