hi. i have a question about the carb. me and my friend both have the same CBR model. same carburetor settings and jet sizes. both have slightly used OEM air filters. stock exhausts and almost all the other parts are stock. but my friend's one is running too rich. we have no clue how it happens.

so i have three questions,
1) we are planning to reduce the pilot screw by 1/4 turn. it will help to reduce this rich condition but will it affect the bike's power in low RPM ?
2) does the pilot screw only affect the idle or a range of low RPM ?
3) even though we have the same air filter, carb settings/jet sizes and exhaust recommended by Honda why does his bike run too rich ?

thank you

 

1) I'd rather my bike be burning fuel at the optimal settings than having it too rich and hope that it will get me more power. I always assumed that the correct A/F ratio (correct air fuel ratio of 14.7 to 1) also would give me the most power as well.

2) I think that I read that the pilot system affects like 1/3 of the throttle, it is more than just idle.

3) How are you so sure that it is running rich? Just to confirm, this isn't an overuse of the choke issue, is it? I try to use as little of the choke as absolutely possible as I know it will foul up the plugs.

There are more than just the pilot system that could make the settings rich. I guess they're called circuits...I'll link a picture to better describe that.
https://www.howtomotorcyclerepair.co...2384914268.jpg

 

thank you very much. there's a slight dry carbon foul in all plugs. we can see that dry soot there. we checked the choke too. it was ok and was in closed position.