low idle... running rough down low

[dongie189]

my 93 idles very low and runs pretty rough in the low RPMs... the mechanic who inspected the bike told me to just try running sum cleaner through my next couple tanks... if this doesnt fix the problem do you guys have any other suggestions?

[M in KC]

Does it idle low and run rough after the engine is up to operating temperature? These bikes will stumble around until thye get warm. I wouldn't advise adjusting your idle until the motor is up to operating temp. But once it is you can adjust it up if you need. Where is it currently idleing at? Is your choke working properly? What is the known condition of your air and fuel filters and your spark plugs? SeaFoam and other cleaners can work in certain circumstances.

My advise would be to sort it out this way 1. good fuel 2. new or recently changed fuel filter 3. new or uncompromised air filter 4. new or uncompromised spark plugs 5. engine up to operating temp and adjust idle as necessary (IIRC 1100-1200 rpms) but I would need check a service manual to be for sure. If all those items are good and your idle adjustment after the motor is up to operating temp doesn't improve your low idle/rough running then a treatment of some appropriate cleaner could be used. Again you and I have a bike that is 16 years old if you still have the original throttle and return cables that haven't been adjusted over the years they have likely stretched and now your slides hang lower in the bodies of your carbs and thus your idle is lower and the motor runs rough. Just one theory.

[DonTZ125]

M in KC - ummm... you do realise these bikes use CV carbs, and the length of the throttle cable has nothing to do with the position of the slides? (Ok, for the pedantic out there - a stretched cable will affect the position near WFO, but not at idle!)

Beyond that, I agree with what you said - carb / FI cleaner and check the easy stuff first, then balance and set the idle. If it still doesn't play nice, strip and clean the carbs.

[dongie189]

it idles around 800(pretty rough)... got the bike the end of last season so i still have a lot on my to do list (fuel filter, air filter, plugs) hopefully that will help. just dropped money on new tires and mirrors, so far ive only done an oil change but it did pass inspection!

i only put premium in the bike... still way cheaper than filling up the f150 haha

i have no idea if the throttle cables have been adjusted... didnt even think to check them out, thanks... ill see how it idles/runs after doing the fuel and air filters and plugs, do i have to pull the tank to get to the carb/idle screw?

[the_finch]

The carbs actually have an idle knob that you can access while stopped at a light.

Sit on the bike with it in neutral. Reach your left hand under the frame rail (just under the choke/petcock area). Carefully feel around (it's hot!) until you find the little knob under there. Turn to adjust idle as necessary.

I didn't get a manual with mine, so I found mine by accident.

[megaloxana]

do i have to pull the tank to get to the carb/idle screw?

no, get a phillips screw driver and adjust the idle knob. Ive included some pictures to help you.

This is what the knob looks like on the carbs.



This is approximately where it is located, you should see it and should be able to turn it with a screw driver from here.