Monday, 22 July 2013


If you live in the USA click here for Used / new Aprilia RS 125 parts 


SEE also the basic maintenance specifications post for measurements and recomended oils etc.

The RS provides the high potential for circuit use. Lack of the basic maintenance, however, will result largely degraded performance. Servicing should be regularly performed and parts be periodically replaced, if needed. 

aprilia racing
aprilia rs125 

Periodic replacement parts see your manual
Item Intervals Criteria 
Plug cap Every (cleaning for each maintenance) 
Cylinder Wear or damage 
Piston Damaged skirt or wear 
Piston ring Partial loss of identification point, wear 
Piston pin Burning, damage, stepped wear 
Piston pin clip (Every time clip is removed) 
Connecting rod small end bearing Burning, wear, damage 
Crank shaft ormation, damage 
Clutch outer Wear, damage 
Spark plug Wear 
Ignition coil Wear, damage 
Reed valve Loose, damage 

rs125 spark plug
aprilia rs125 spark plug 

other items needing regular attention
Front/rear suspension 
Cables (throttle or clutch) 
Brake master cylinder 
Steering stem 
Suspension link 
Wheel bearings

aprilia rs125 shock 

Checking other fasteners
Check the brake system, front section, or rear axle section for loose fasteners. 


aprilia rs125 vertex piston 

• Piston contact
Piston contact should not usually be removed. Severe contact with the cylinder is attributed to some other reasons. Pistons have special profile (out of round), which is designed to produce heat emission, providing proper contact when pistons and cylinders are subject to deformation.
Accordingly, careless piston modifications in profile will degrade the ideal profile, resulting in more contact with other portions.

Ring sticking

With the increase of service engine speeds year after year, even if keystone rings are used, sticking may result.
If rings and pistons are new, ring groove modifications are not required against sticking. However, if stuck rings are found at the time of maintenance, the modifications must be done. Stuck rings may cause engine troubles as well as a significant power drop.
Stuck rings can be identified by signs of a failure exhibited at the engine start, such as unwillingness to start engines or abnormal engine noise emitted from the silencer.

aprilia rs125 cylinder barrel 

                                                                aprilia top end removal / refitting
                                                                      top end rebuild video

Extreme care should be exercised during handling cylinders or cylinder heads.
In particular, flawed mating faces may deteriorate adherence, causing blow by.
If there are projections caused by flaw or dent, they should be removed using abrasive paper to make the surface flat.
However, if flaws are present across O-rings or flaws are present in the O-ring grooves, appropriate cylinders or cylinder heads should not be used since O-rings cause blow by. 

aprilia rs125 engine clutch plastic gears 

aprilia rs125 carb 

                                                      Aprilia Clutch removal and refitting video

Clutch outer section 

The clutch outer section should be periodically serviced and replaced if necessary. If excessive plays or cracks are found during servicing, defective parts should be replaced as soon as possible. 


When cleaning carburetors, do not apply high pressure air to carburetors with floats installed. High pressure air would cause oil level in carburetors to get out of order, resulting in significantly wrong settings. 

Carburetor float 

Carburetor float section is a very delicate part. Extreme care should be exercised during disassembly.
If oil level should go wrong, see owners' manual for proper adjustment. Wrong oil level would cause rich or lean mixture, or hesitation. Also, check that floats are smoothly going up and down. 
If floats do not move smoothly, rich feeling or hesitation may result when beginning to open the throttle. Also, unstable fuel mixture would cause frequent detonation. 

Making reed valves thinner allows easy opening, and installation of supports secures functioning of valves when wide-open.

aprilia rs125 reed valve 

wiring connector blocks are prone to corrosion and cause many electical problems so clean these 
out regular also .

basic aprilia rs125 maintenance

aprilia rs125 chain sprocket 

drive chain and sporkets

chain stretch , maintain regular lack of maintence will 
damage your sprocket more quickly.
check for play via WSM .

oil the chain whilst warm after being ridden .

aprilia rs125 brake caliper and pads 

brake pads 

check pads visually for friction material wear , replace when low 
but long before they may damage disc .

aprilia rs125 battery 


check fuid levels (uper-lower levels)

aprilia rs125 air filter 

air filter 

clean frequently AFTER cleaning reoil the filter element
without oil you filter is useless .

aprilia rs125 iridium spark plug 

spark plug 

inspect for wear , wire brush clean , re gap or even better replace
they are cheaper than chips .
makes sure you fit exact spark plug .

aprilia rs125 fuel tap 

Fuel system 

inspect fuel tap and pipes , clean filter on the tank and at the carb and any inbetween.


clean filters in tank and carb if you suspect fuel starvation ,if not used for long intervals 
turn off fuel but expect to clean carb out before reusing bike
ive known this to occur after only a few weeks 

aprilia 34mm carb strip down video 

                                                       28mm carb strip down video


make sure all cable are in good order no fraying or other damage make sure all are adjust correctly 
especially the oil pump setting < visually check oil is being delivered 
i do this everyday maybe more often .

idle speed 

make sure this is set correct after adjusting cables .

cooling system 

check coolent level , check for leaks ,check fins of radiator for blockage clean if ness ,
signs of water in the oil then seals could be gone on the water pump , rust coluoured ? flush system and clean , check anti
freeze levels after , you can test thermostat in hot water if you want to also 
but not really basic maintenance .

Rave valve 
regular maintenance of this is important as deposits on blade with cause bad running and wear soloniod faster ,
remove valve from cylinder and clean thoroughly .
fit as per WSM and adjust cable and pv gaps correctly !!

exhaust and silencer 

clean these out at regular intervals ( not cat models just silencer) replace gaskets on refit .

transmission oils , 2t oil 

obvioulsy 2t should be checked daily , it seems to happen a lot where people run out of 2t 
this is stupid these bike will last about 3 or 4 miles if you lucky with 2 stoke oil this should be a daily 
check or even after every journey , also check that your pump is delivering the 2t correct and check for sir locks
and bleed oil pmup through some times water can acumulate in bottle and this seems to block line , i always bleed oil pump
untill good clean oil is coming out .

check the sight level glass on engine for oil levels regular , top up where neccesary and replace regular .
as per WSM .

check brake system over 

check levers and pedals for correct operation , any looseness , out of shape or any damage whatsover replace , make sure all mounts
and brackets banjo bolts etc are tight and not leaking , check pads for wear see earlier , and top up fluid levels ,check alll hoses for 
twists damage etc , if brakes are spongy then bleed brakes , i change the fluid on all new bikes i get completely i flush new fluid by bleeding untill
clean fresh oil comes out , check  brake lights and switch function correctly , inspect the discs for any damage scrathes out of true , wear etc , 

wheels and tyres

check tyre condition and tread depth , check  wheels for balance , and check bearings for excessive play  .


Aprilia rs125 Fork removal video 

very important to keep regular checks on your suspension .

check  for binding during forks operation , inspect forks for signs of wear , corrosion and pitting , check the oil seaks for signs of weepage
replace where any problems are found .
inspect rear shock for wear and any signs of leakage ,
there should be no binding in operation or any side to side movement of swing arm , tighten nuts if any movement is found ,
pull wheel upwards there should be no play , if this is felt its possbile wear of bearings / or linkages , or mountings replace where needed .

steering head bearings
check for play and replace where neccesary (see WSM) .

lighting system 
check all lights and indicators for correct operation and adjustment 
check the contacts or bulbs and repalce where neccsary .
problems can occur due to corrosion within the connector blocks
these must be cleaned regular .

stand and oiling 
should be lubicated regular as these are exposed to elements , alond with other exposed 
items such are levers , foot rests , brake levers , chain cables , check operation of the stand switch .

oil pump test

oil pump
check that throttle operate pump smoothly , and that all adjustments are correct
ensure scribe mark on pump are aligned perfectly .
check all pipes from and to the pump are safely connected
any leakage must be corrected as ths cause oil starvation to 
engine .
at high milage or after siezure clean out the oilfilter or 
replace pump altogether .
always bleed pump after fitting or hose removal , 
bleed untill good oilis seen leaving the pump ,
see above video on how to test pump any testing or bleeding should be done with 
premix oil in tank to avoid engine damage .
CHECK oil tank level and CHECK oilpump operation daily or even prior to every journey!!.

compression test 

see the post named after this process in the blog
archives or click here , this is an important test and should be
done weekly , if you dont do this and your engine siezes 
then you only ave yourself to blame.
low compression signals piston/piston ring wear 
and these must be changed as soon as the compression 
becomes too low .

piston change

aprilia rs125 top end rebuild video 

easy to do see the dedicated posts to these in archives or click here
ill be updating and making better videos, and posts
and pictures as i go .

front forks oil / seals change

aprilia rs125 fork oil amount 430ml
aprilia rs125 fork oil type SAE 10~20

forks exploded diagram aprilia rs125 

again very easy to do hardest part is removing from the bike
but ill do a video on this soon !! .





Repairing an End Can silencer

Here is an alternate way of repairing an end can if the carbon-kevlar tube is not totally junked and replacing is not mandatory.

The part of the damaged tube must be removed. I would still be comfortable if the rest of it is 20cm in length at least. Use a piece of thick sandpaper to mark your cutting line. Any metal saw will do the rest of the job.

The same length should be removed from the perforated pipe.

And then welded back in again if necessary.


Piston to barrel clearance

 something everyone should have in his toolbox. Piston fit fillers are cheap and very useful. You will need 0.002, 0.0025 & 0.003 inch feeler guages as these will cover most of your needs. 

you can pay up to £400 for a set of feeler gauges not what id pay but you can if you want
me i bought the ones below in link not that expensive but not cheap .


Cylinder honing 
again buy good not cheap rubbish 

aprilia rs125 blog 

see more Aprilia RS 125 posts here 

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  1. Have you got the dellorto carb tuning manual for the 34/28 vhsb please and can I buy it off you

  2. Please contact me about bundles but I need it printed will pay you but only own a phone

    1. hi mate the carb manuals are on the blog free somewhere in the carb posts ,
      i dont have printed ones sorry .