hi i have a 125 gilera runner 2002 plate i have a flat spot when i pull the throtle over half way and start to loose power ive taken it to the garage 3 times and they still cant find the problem. ive had the carb cleaned and re set twice the compression checked,new spark plug ,new egnition coil and a new manifold please can someone help im at my wits end ?

david, March 2010

chech you diaphram in you carb, have had a few go hard and also the slide can score and get worn, also on the side of the carb is a round filter with gold mesh in it make sure this is clean, check to see if it has an accelerator pump on the carb and its not just running off the fuel from that, also check your ignition coil, blue in clour right hand side of th frame jst behind inspection cover where your right foot goes, sometimes the lead will go very hard and brittle causing it to break internally causing flatspots and hesitation

m, March 2010

p.s is it a two or four stroke model ie a vx or a sp or fx as this will affect my answer just given if its four stroke.

adam bike doctor, March 2010

ok sounds like you have taken it to some muppets,i would give the job up if i couldnt fix that problem.
ok try this where the airfilter draws its air from the atmosphere it has a concertina type air hose if you look at it from the left side of the bike (kickstart side)you will see the big air box and behind it the black air pipr from the air box to the back of the carb and to the left of it a hise as described above(concertina pipe)i would try to restict the flow of air on this hose by maybe putting a couple of pegs on it just to establish if its weak or not.the problem sounds like the mixture is weak and this will increase the vaccum in the carburettors venturi if you put these pegs on the pipe therefore pulling more fuel up from the main jet.see if this helps it and get back to me.it may also be a prob with either the reed petals or one of the crankseals.it may even have water in the fuel or have a faulty fuel pump or ir leak.just let me know if the pegs make it a bit better first.

adam bike doctor, March 2010