rs125 question

dardappa2004 · Nova Slayer Joined: 02 Mar 2008 Karma :

hi there fellow bikers,

what would you recommend for an rs125 with a big bore kit on and a cone air filter for jet sizes and needle height? At the minute it has a 155 main jet? i just wanna improve top end as feels as if it stops pulling above 90mph so i dunno???? the spark plug is carbon fouled so how could i also sort this????

Many thanks in advance Thumbs Up

bmwsport · Nitrous Nuisance Joined: 25 Oct 2008 Karma :

155 is pretty heavy.. my f.p rs125 with a arrow exhaust runs a 120.. i take it you have the 28mm carb still?

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hi,
get a few different sized main jets & start plug chopping, lol
but if you still have the standard 28mm carb, then you definately need the vhsb 34mm & manifold.
if its the 34mm carb you already have, that main jet is way too small, you should be looking at around 168+ for a bbk. (which bbk is it?)
cheers,
GAZ

dardappa2004 · Nova Slayer Joined: 02 Mar 2008 Karma :

hi there , yea i have a 34mm carb erm i bought a 185 tried that and wouldnt rev past 6000rpm . I have 159cc polini one? Thought that its runnin rich so shouldnt i down size? im really a noob when it comes to carbs Crying or Very sad

dardappa2004 · Nova Slayer Joined: 02 Mar 2008 Karma :

hi there , yea i have a 34mm carb erm i bought a 185 tried that and wouldnt rev past 6000rpm . I have 159cc polini one? Thought that its runnin rich so shouldnt i down size? im really a noob when it comes to carbs Crying or Very sad

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hi,
i wouldnt have thought you would need to go smaller.
i was running with a 162 main jet,34mm carb, jl twin exhaust & vectorcone airfilter.
& that was without a bbk.
get a hanfull of jets & start plug chopping, lol
suppose it depends on what other mods you got? (what exhaust you got?)
still think you should be looking at around 170-175 though.
whats the mixture screw at?
& needle height?
how does it perform throughout the rev range?
it may well be running rich, but not at wot.
hence the need for a plug chop.(with a clean plug)
might just be simply a case of moving the clip on the needle.
cheers,
GAZ

dardappa2004 · Nova Slayer Joined: 02 Mar 2008 Karma :

i have the exhaust that came with it, its de-catted. ok so ill buy some bigger jets and adjust needle height and guess it trial and error,

Many thanks

Cool