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Aprilia Rs125 workshop manual < claim your free manual here
Thursday 26 April 2012
Aprilia RS 125 engine removal / top end removal RS125 barrel cylinder piston replacement
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| Aprilia RS 125 engine 122 |
Aprilia rs 125 Rotax 122 engine removal
Aprilia RS125 engine removal refitting video
Aprilia RS125 top end rebuild
video
Top end removal pictorial (video)
Tools required:
5 and 6mm allen key
11mm ring spanner
13mm spanner
screw driver
stanley knife blade
mallet
needle nose pliers
10mm spanner
Additional key items:
2 stroke oil (I recommend castrol TTS)
A clean rag
window silicon, ideal for the o rings when they do not stay in place
New Spark plug
Full Top end rebuild items:
New cylinder or reconditioned cylinder
New piston
New piston rings
New little end bearing
New C clips
Top end gasket set
First off you need to remove the tank , once you have that off, remove the airbox (not easy)this will give little more space to work in you can remove the top engine mount .
Now you have even more room to work in you can go ahead and remove the carb/reedblock/manifold assembly in one go, you need to remove the 5x 5mm allen key bolts from the manifold then the whole lot will slide out and can be moved to the side of the bike out of the way , this was you can keep the throttle cable and oi line connected to carb.
undo coolant drain bolt the coolant ,as you will be removing the cylinder head and water jacket and these a filled with coolant and can be messy . There will be a drain screw on the LHS crank case cover, at the front, it will say DRAIN above it.
Tools required:
5 and 6mm allen key
11mm ring spanner
13mm spanner
screw driver
stanley knife blade
mallet
needle nose pliers
10mm spanner
Additional key items:
2 stroke oil (I recommend castrol TTS)
A clean rag
window silicon, ideal for the o rings when they do not stay in place
New Spark plug
Full Top end rebuild items:
New cylinder or reconditioned cylinder
New piston
New piston rings
New little end bearing
New C clips
Top end gasket set
First off you need to remove the tank , once you have that off, remove the airbox (not easy)this will give little more space to work in you can remove the top engine mount .
Now you have even more room to work in you can go ahead and remove the carb/reedblock/manifold assembly in one go, you need to remove the 5x 5mm allen key bolts from the manifold then the whole lot will slide out and can be moved to the side of the bike out of the way , this was you can keep the throttle cable and oi line connected to carb.
undo coolant drain bolt the coolant ,as you will be removing the cylinder head and water jacket and these a filled with coolant and can be messy . There will be a drain screw on the LHS crank case cover, at the front, it will say DRAIN above it.
Once you have drain coolant out , remove the HT lead and the spark plug.
Now remove the 4x5mm water jacket bolts so you can remove the water jacket, which will reveal the cylinder head, there will be 5x13mm bolts, which may be tight to undo, undo these each diagonally opposite to stop any possible cylinder head warping. Dispose of any gaskets or o rings, also clean the surfaces where the gaskets have been very carefully with a stanley knife blade.
Now you need to remove you PV from the cylinder, or blanking plate if you have a restricted bike (2x5mm allen key bolts).
Now the cylinder itself is ready to be removed ,try to avoid small parts falling into the crank case if you do engine removal and swilling out with old diesel will be required
, first remove the 4 bolts at the base of the cylinder (11mm spanner, also remove them in a diagonal fashion) once they are removed, lift the cylinder off the crank case making sure its going up straight and not at an angle, lift it about 25mm and stuff a rag into the crank case tightly t avoid any debree falling into the crank case.
Once the cylinder is out of the way you can begin to remove the C clips which are are at the side of the piston (set in about 5mm) once these are gone remove the piston pin / gudeon pin this can be tight so be carful when tapping and removing it brace piston if tapping is required once pin is removed, the piston will come off the con rod and you can remove the little end bearing.
Now remove the 4x5mm water jacket bolts so you can remove the water jacket, which will reveal the cylinder head, there will be 5x13mm bolts, which may be tight to undo, undo these each diagonally opposite to stop any possible cylinder head warping. Dispose of any gaskets or o rings, also clean the surfaces where the gaskets have been very carefully with a stanley knife blade.
Now you need to remove you PV from the cylinder, or blanking plate if you have a restricted bike (2x5mm allen key bolts).
Now the cylinder itself is ready to be removed ,try to avoid small parts falling into the crank case if you do engine removal and swilling out with old diesel will be required
, first remove the 4 bolts at the base of the cylinder (11mm spanner, also remove them in a diagonal fashion) once they are removed, lift the cylinder off the crank case making sure its going up straight and not at an angle, lift it about 25mm and stuff a rag into the crank case tightly t avoid any debree falling into the crank case.
Once the cylinder is out of the way you can begin to remove the C clips which are are at the side of the piston (set in about 5mm) once these are gone remove the piston pin / gudeon pin this can be tight so be carful when tapping and removing it brace piston if tapping is required once pin is removed, the piston will come off the con rod and you can remove the little end bearing.
Aprilia RS125 top end rebuild video pictorial
Friday 20 April 2012
Aprilia RS 125 carb jetting jets 28mm 34mm RS125
A simple equation for figuring you main jet is to multiply dia of carb by 5 and then multiply buy 0.85 for stock 0.9 for bike with sports airfilter fitted 0.95 for airfilter and exhaust .
28 x 5 x any of 0.85 - 0.90 - 0.95
3. float
4. atomiser
5. idle tube / pilot jet < same thing
7. needle valve and seat
8.main jet anti surge washer
air fuel is the angled screw towards the air box and is a air screw (not the one with the spring on thats the idle screw)
out =more air to fuel
in = less air to fuel
float height set at 14mm dellorto suggest 11 mm i ran 14mm tho
Aprilia rs125 34mm carb strip down video
The purpose of the carburettor is to provide your engine with the correct ratio of fuel and air. Although the carburettor can’t provide the ideal mixture at all loads, the different parts of the carburettor work to try and create this ideal mixture for proper combustion.
see more Aprilia RS 125 posts here
Aprilia rs125 carb jetting 34mm and 28mm
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Aprilia rs125 28mm carb on Ebay UK here |
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Aprilia rs125 carb jets on Ebay Uk here |
Dellorto PHBH28BD standard
you do not need to re-jet for derestriction but its always advisable after any change to do a plug chop test to test combustion conditions , this will give a clear indication of the jetting and running condition inside the cylinder , also its recommended to increase jets size 5 points for any sports airfilter or exhaust fitted and again do the plug chop test to ensure correct running conditions this is a good habit to get into after doing any work on your bike that may after fuelling .
starter jet 70
main jet 120
pilot jet 62
slide needle valve bn266
float needle valve 250
1. choke jet
2. main jet 3. float
4. atomiser
5. idle tube / pilot jet < same thing
7. needle valve and seat
8.main jet anti surge washer
air fuel is the angled screw towards the air box and is a air screw (not the one with the spring on thats the idle screw)
out =more air to fuel
in = less air to fuel
float height set at 14mm dellorto suggest 11 mm i ran 14mm tho
155 main
36 idle jet
1.5 turns out on the air screw
60 choke jet
k57 needle top notch
app 266 needle jet / atomiser
Aprilia rs125 34mm carb strip down video
The purpose of the carburettor is to provide your engine with the correct ratio of fuel and air. Although the carburettor can’t provide the ideal mixture at all loads, the different parts of the carburettor work to try and create this ideal mixture for proper combustion.
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Aprilia rs125 28mm carb see them for sale on Ebay UK |
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| You could just dump it all in your ultrasonic cleaner , get one they are excellent  |
Aprilia RS 125 carb set up , how do you do the plug chop , test engine running conditions RS 125
Basically a plug chop involves putting the bike under load at high revs
Chopping is where the ignition is cut at a certain RPM while the engine is under load
Hit the kill switch and pull clutch in fast , Slow down and with gloves on remove spark plug (hot).
the plug will have a colour which can be checked to given running conditions inside the cylinder at what every RPM or throttle position you did the run at . ie third , half full throttle or certain rev ranges .
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Black = rich
Brown = good
Grey / white = dangerous conditions
for advice on jetting and which jets to use see here
CARB SETUP
Set it to rev at 2000 with the idle screw, then twiddle the air screw just to the left of the idle screw... turn it all the way in, then back out 1.5 to 2.5 turns, listening to engine. As you turn it, revs should increase slightly. Set it to a point that revs are at highest and smoothest. Now use the idle screw to tune it back down to around 1100rpm ( i normally set mine at 1500rpm )... that should be the carb as set as it can be.
Carburetor Tuning : Listening For Rich And Lean Conditions
for advice on jetting and which jets to use see here
CARB SETUP
Set it to rev at 2000 with the idle screw, then twiddle the air screw just to the left of the idle screw... turn it all the way in, then back out 1.5 to 2.5 turns, listening to engine. As you turn it, revs should increase slightly. Set it to a point that revs are at highest and smoothest. Now use the idle screw to tune it back down to around 1100rpm ( i normally set mine at 1500rpm )... that should be the carb as set as it can be.
Carburetor Tuning : Listening For Rich And Lean Conditions
Carb settings and adjustments tutorial
Video series
BUY the ultimate Aprilia RS 125 workshop manual bundle HERE
Aprilia RS 125 RS125 air filters
Aprilia RS 125 Airfilter
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aftermarket air filters , They look good,
get rid of the horrible box but there is more to it than just putting it on.
If its a decent aftermarket air filter then it should let more air into your engine. Therefore you will need to alter the jetting otherwise your bikes engine WILL seize (more air in more fuel needed).
Basically, to put your new air filter on, simply remove the tank, remove the old air box and put on your aftermarket air filter.
some say they will add a bit of BHP but you probably wont feel the difference tbh,
just it will give a better induction noise and maybe a slight boost main advantage is getting rid of large airbox and looks .
Once you have fitted it you will NEED to do a plug chop test.
or even better dyno test machine and having carb jetting set correctly .
AIR BOX MOD
First off the snorkel/trumpets...
Take the tank off your bike and you will see your air box, coming out of it at the top will be a piece of rubber called the snorkel/trumpet... some say take the whole thing out others say pull it out, cut the end off that went into the air box then turn it around so that the end that was outside the air box is now inside it.
This will give a better induction noise, boost mid range power, however people can experience bad splutter around 5-6k,
change your jetting and this should improve and do a plug chop to test running conditions.
get into this habit , make any changes , do any work , test running conditions , spotting lean conditions will save you money and achieve longest life out of your engine.
get rid of the horrible box but there is more to it than just putting it on.
If its a decent aftermarket air filter then it should let more air into your engine. Therefore you will need to alter the jetting otherwise your bikes engine WILL seize (more air in more fuel needed).
Basically, to put your new air filter on, simply remove the tank, remove the old air box and put on your aftermarket air filter.
some say they will add a bit of BHP but you probably wont feel the difference tbh,
just it will give a better induction noise and maybe a slight boost main advantage is getting rid of large airbox and looks .
Once you have fitted it you will NEED to do a plug chop test.
or even better dyno test machine and having carb jetting set correctly .
AIR BOX MOD
First off the snorkel/trumpets...
Take the tank off your bike and you will see your air box, coming out of it at the top will be a piece of rubber called the snorkel/trumpet... some say take the whole thing out others say pull it out, cut the end off that went into the air box then turn it around so that the end that was outside the air box is now inside it.
This will give a better induction noise, boost mid range power, however people can experience bad splutter around 5-6k,
change your jetting and this should improve and do a plug chop to test running conditions.
get into this habit , make any changes , do any work , test running conditions , spotting lean conditions will save you money and achieve longest life out of your engine.
Also, purchase another panel filter, e.g. CMP Racing, Pipercross. These are usually washable and oiled, this will give a better induction noise too and better running of your bike.
Again, id re-jet not just stick it on
Aprilia RS 125 RS125 suspension tweak , adjustable shock
Aprilia RS 125 RS125 suspension tweak , adjustable shock .
i would not personally alter a road bikes suspension set up they ride pretty much fantastic on normal settings , doing so is at your own risk .
Setting up your suspension.
sliding your forks up through the yokes 1.5cm will increase the angle of attack and turning speed of your bike.
APRILIA RS 125 CHAIN SPROCKET INFORMATION ( WHATS BEST SIZE SPROCKET ) RS125
Aprilia RS 125
Sprockets:
The bigger your front sprocket is the faster the top end, the smaller it is the faster the acceleration .
The bigger on the back the quicker the acceleration the smaller the better the top end.
The standard set up is 16/39
39 tooth sprocket on the back , 16 on the front.
Change the size of sprockets for more or less acceleration/top end.
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| Aprilia rs125 sprocket mph graph |
bit more but it is well worth it as usual you buy cheap you get cheap
and with chains and sprockets you do not want any failures best to
stick with standard than change to cheap sprockets and chains .
see the sprocket calculator
the Aprilia rs125 blog
a sprocket mph calculator
sprocket calculator
I use DID gold chains as they are excellent and look great too .
Aprilia RS 125 34mm carb info RS125
.JPG "Aprilia RS 125 34mm carb info RS125")
.jpg "Aprilia RS 125 34mm carb info RS125")
.jpg "Aprilia RS 125 34mm carb info RS125")
.jpg "Aprilia RS 125 34mm carb info RS125")
1Choke jet
2. main jet
3. float
4. atomiser
5. idle tube / pilot jet < same thing
7. needle valve and seat
8.main jet anti surge washer
air fuel is the angled screw towards the air box and is a air screw (not the one with the spring on that is the idle screw)
out =more air to fuel
in = less air to fuel
float height set at 14mm Dellorto suggest 11 mm
APRILIA RS 125 Carb
8.main jet anti surge washer
air fuel is the angled screw towards the air box and is a air screw (not the one with the spring on that is the idle screw)
out =more air to fuel
in = less air to fuel
float height set at 14mm Dellorto suggest 11 mm
APRILIA RS 125 Carb
The older bikes uses a 34mm carb. The newer bikes have a 28mm carb. it was the pre 98 versions that were fitted with the 34mm carb , then after that unless modified it was a 28mm carb.
for better mid range power, and a better top end fit the 34mm carb.
for better mid range power, and a better top end fit the 34mm carb.
All you have to do is get hold of a Dellorto VHSB 34MM and a new inlet manifold because the original will be to small and then fit it onto your bike. The standard air filter will still fit this new carb.
check running conditions inside engine after every job you do like this , plug chop .
155 main
check running conditions inside engine after every job you do like this , plug chop .
155 main
36 idle jet
1.5 turns out on the air screw
60 choke jet
k57 needle top notch
app 266 needle jet / atomiser
You could just dump it all in your ultrasonic cleaner , get one
they are excellent
BUY the ultimate Aprilia RS 125 workshop manual bundle HERE
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