why does my rs125 aprilia splutter ?

hi
I have aprilia rs 125 07 I was doing about 60mph on my way home and then I lost power it was doing no more then 40mph I just made it home i brought all new head gaskets and piston and rings all rubber seals to i put it all together and when i put water in the bottle it took 2 jugs full off water when i try to start bike without spark plug in there was lots water spitting out off hole where spear plug gose why that anyone no why that is

waynee
February 2015

Hi I've not long bought a rs 125 iv owned 1 b4 had to the best bike I've owned so I recently brough a new 1 its a 08 plate I'm having a aproblem with the revs it seems to be limited it revs to 10000 iv drilled the cdi gettin good speed top evarythink is workin as it should but I'm missin the best part ov the rev range can eney 1 point me in the right direction as what to do thanks.

scott
October 2013

hi adam,
crank seal gone??!!!!! i dont like the sound of that.
what sort of smell are we talking about?

ive had a look at the cdi and no it has not been carved out.
(which fooks me off because ive just sold a power kit with 1 of them in it. :-(
i got told that befor about doing that bridge thing befor but just didnt have a clue how to do it.
did you manage to find one at work?
(what is it you do my friend,? )

i will hang in there adam as i love these rs's and its the only 125 id have.
once again thank you for all your help doctor. speak soon.

a very sad steve
August 2010

steve it sounds like the crank seal on the left hand side of the engine may be gone .its hard to tell from what you have said for sure but it will have funny smelling smoke from the exhaust if it has,these dellorto carbs that they fit to these bikes are really crap though and it takes alot of tuning to get them running ok.another thing to check is that the rev limiter isnt still active as it sounds like it is to me,there is a small section of the cdi unti that you carve out and then break a small metal tag that unlimits the revs the cdi unit is right up under the pillion seat and really you need to know where to dig into it for the tag ill have a look at one i have got at work and see where the tag is and also it may be worth googling it.good luck hang in there with it steve

adam bike doctor
August 2010

hi again adam bike doctor.

i took carb off and cleaned it and made sure all the jets were not loose.
put it all back together.

i also changed the power valve servo and when i did that the power feels alot better (when not spluttering)
but it still does splutter.
also if im riding down the road and pull my clutch in and rev the bike it only gets to about 8-8 and a half thou and then sounds like its bogging.

when i said my power valve blade it blacky wet, so is the spark plug.
ive just order a new 1 and that a iridium 1.

my bike is a 52plate.
thank you again for all of your help. i really am greatfull.
hope to hear from you soon.

a very sad steve
August 2010

lol i knew it would be a 122 rotax as its only the early chesterfield m1 rs's that have the 123 as a rule and af1 futuras and europas.the powervalve blade will always look like that mate they get blasted with burnt 2 stroke oil when its running.to get to the carb just undo the two 8mm headed bolts from each corner of the air box note only two(diagonally) hold it to the frame then undo the big clamp on the back of the carb to air box and lift the airbox out,then undo the smaller front carb clamp and pull the carb out or twist it so you can get to the 14mm bolt on the bottom of it in the centre,undo this (fuel will pee out) then pull the float bowl off and you will see 3 jets the biggest one is the main jet and the other two are a pilot jet and a choke jet check all the sizes and clean any water or crap out from the float bowl ok good luck.adam

adam bike doctor
August 2010

hi there adam bike doctor.
thank you for your reply.
it is a 122 engine (how did you know)

it is the servo power valve and when i lifted the tank up and rev'ed it the cable didnt move till over 6 thou rpm,
ive just changed the servo and it now moves at about 3 thou rpm.
also when i removed the spark plug and the power valve blade both were wet throughg,
like a blacky oily wetness.
the exhuast thats on it is a leovince but ive just brought a standed exhaust that has been cut open and had the cat removed.

ive never opened a carb before (belive it or not)
so i really dont have a clue with them.
what may i need to do?

thank you so so much for your help with all of this mr doctor.

a very sad steve
August 2010

sorry steve i dont do private emails,but i can suggest the problem/s that the bike may have
firstly i assume its running a rotax 122 engine?
these bikes use a dellorto carb and have a choice of at least 3 different venturi sizes it will be apparent in the number on the side of the carb i.e something like phb28... the 28 or whatever it is refers to the venturi size.
now this spluttering is likeley to be one of 3 things
1,the choke may be stuck on or a jet has come loose and the carb is putting too much fuel into the crankcase and making it run very rich
2,the powervalve is shut completeley(is yours a model that has a servo assisted powervalve ?)
3,the exhaust has a collapsed baffle or more likeley a catalyst that has come loose(very common)
to be honest the most likeley is 1 or 3 above if you have a mate who has an rs try his pipe and his carb one at a time if not then check your choke is shutting right off by seeing if there is free play in the cable when its off and check the jets are tight and the sizes are right for the carb size
then take the exhaust off and give it a shake and see if you can here any loose bits ,if you can saw it in hafl and take any loose stuff out and any catalyst and get it welded back up
also check to see if the powervalve has any cable going to it ,its on the front of the barrel just above the exhaust pipe.
let me know what you find ok.

adam bike doctor
August 2010