Hi i have an aprilia sx 125 it is a 2010 model and i bought it a few weeks ago it came with the warranty book but no service stamps in it. My problem is that when running the bike mainly in 4th gear at 4500 revs doing 30ish , in 5th gear doing 5300 revs and 40ish the bike keeps losing power like then gaining again for instance when you pull back the throttle the bike hesitates. The bike just loses power then gains power then loses then gains I don't know if this is due to air intake or maybe a blocked jet any help Thanks Tony

David Parker

• 333 Answers
• Posted on Aug 10, 2009

SOURCE: Aprillia SX125 spluttering Mid revs too

Can you confirm if this has a 28mm Dell'Orto carb ?
I would think that you might be possibly running too rich in mid range between ¼ and ¾ throttle opening in which you could try to drop your needle (raise the clip)by two notches,and if this helps but not eliminates the problem,maybe a slightly smaller main jet.

Please get back to me if you need more help.

Thankyou

SOURCE: spluttering in mid revs.

Hi ....... The excuses you've been given might hold up either in Oz or tibet but as you say in Ireland it doesn't quite hold water.
Has anyone changed anything ? Pipe, airfilter, ignition ? The fact it takes off in the powerband show it's either not too bad or you've been luckey not to hole a piston. Try removing the spark plugs and note the colour, any colour other than a light tan is NOT correct and indicates fuel mixture as too lean/white (too much air) or rich/black (too much petrol). Too rich is preferable to too lean as being lean will hole a piston, burn out a valve or a partial/full seizure. Dependant on colour I'd then LOWER the circlip on the carb needle.
Let me know how you get on.

scott rimmer

• 162 Answers
• Posted on Feb 26, 2009

SOURCE: Bike won't rev up

i have had a lot of experience in this bike, the parts are really hard to get hold of from experience. this did happen to me but mine had a 65 bore kit on it and it turned out to be the bearings. there is not much that can stop a two-stroke bike reving up like that as the mechanics inside are very straight forward. a good tell tale is to check the inside of your sump plug, if there are filings on it as it is magnetic, this is more than probably the bearings and will need rebuilding. really sorry if this is nto the answer you are looking for.

SOURCE: aprilia starting problems

check the gap on the plug

Testimonial: "the gap was too big thanks so much"

Murtaza Akberali Versi

• 767 Answers
• Posted on Oct 30, 2009

SOURCE: Aprilia RS 125 Power Loss

I guess youwillhaveto adjust the clutch cable so as to open the plates more at the pressure plates to let the clutch plate rotate freely instead of binding thus the low rpm.
Hope this helps!