hello i need a help
in my friend's CBR250RR the idle had been set to 2500rpm. we tried to reduce it to 1500rpm (while the engine was hot) which is recommended by Honda. but when the rpm needle came around 2000rpm the engine died. it happened several times in several attempts.
so we removed the carb and cleaned, put the mixture settings to the standard and balanced, cleaned the petcock and also checked the ignition system and charging with a multimeter. all were in specs and working fine.spark plugs were bit old but didn't noticed any dry or wet fouling at all. they were all in tan color.
but still we couldn't set the idle to 1500rpm. if we were to keep the engine running we had to set idle to at least around 2500rpm. what could be wrong with this bike? can some one give some advice please. thank you

 

How did you sync the carbs?

 

first i bench synced it after cleaning the carb. then i synced it using a manometer. i had used the same procedure for my bike which is also a CBR250RR. it idles fine at 1500rpm. thx

 

That sounds right. Are you sure that the tach is correct? Mine is off by about 100 rpm.

 

at the time he bought the bike the RPM gauge wasn't working. later it was repaired. may be something is wrong with that. coz even though it's at the 2500rpm, it seems much lower by the engine sound. pretty strange but it does. may be we have to check that rpm gauge again. thx

 

no worries. you might want to pick up a bench tach to troubleshoot with. Mine is an Actron and it's accurate and easy to use. I think they are $30-40US, but you may find them cheaper

 

thank you very much for the details. i'll look for it. thx again

 

+1 on it being the rev-counter, especially after what you said about repairs.

If you have your own bike to compare, I'd just go by how the two bikes sound.

 

yea i have the same bike model. will compare it with my bike. it seemed much lower than 2500rpm by the engine sound. thank you