Cant Figure out why Bike cant idle

[niteblade]

i finally got my cbr400 issues sorted out but now my cbr125 started having issues idling....

The bike keeps stalling at idle when cold unless i hold the throttle the keep the revs up...
once warmed up the bike runs perfectly fine

When im riding and coming to a stop at a traffic light, the bike stalls once i clutch in and let the revs drop.... after warming up, its fine tho...

i've took out the carbs for a good cleaning and changed all the possible stuff like the spark plugs, air filter etc...

i've tried adjusting the idling screw... the bike idles at 1.5-1.7 when warm but when its cold it is around 1-1.2 and barely seems to be able to stay running

the rpm seems to get stuck at 4-5k RPM randomly when reving in free gear too when it warms up

can someone help me? im really at a loss here

[tigerclaw]

This is a bit of a guess but it sounds to me like its intermittently pulling air through between the carbs and the motor at idle its leaning out to much and dying and when you rev it in free gear its also leaning out and holding the revs

[Goulime]

Do you look at carbs trumpets ? If they are not seal perfectly in carbs they can do that. (Too much air, some time ...)

[dunkenb]

Check the inlet rubber that mounts the carb to the cylinder??

[niteblade]

i've done some reading up on the issue and it seems that this is a jetting problem... my mech put in 115 and 38 size jettings instead of the stock 118 and 35 (can anyone clarify whether this is really the stock size for cbr125)....

it seems to me that the bike has poor acceleration when it is cold so its running lean?

i'll probably try going one size bigger but what confounds me is the pilot jet

it seems that my bike's idle is rich when cold and lean when warmed up(sometimes gets stuck at 4krpm then slowly goes back down).... so how do i go about trying to remedy this?

Lean condition: Poor off idle throttle response, idle that flutters a little after a throttle blip then slowly returns to the idle that you've set, popping back through the carbs when the throttle is blipped.

Rich condition: Off idle response may be good unless plugs are fouled from a way too rich mixture. After a throttle blip the motor will dive down below set idle and will either die if way too rich or may return to set idle if it can recover.

[bourne92]

Id start by checking for an air leak first mate. Start the bike up and spray wd40 around the intake/carb rubber etc.... youll know if you have an air leak or not

[dunkenb]

Lean when warm maybe because every thing has expanded and more air is getting in somewhere, if the carbs be off a few times i'd check its seated properly, And fit the standard jet sizes.