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Problem with my 125CC Bike? Answered

In day time i find my bike running not smoothly.But in night time i found that my bike is running very smoothly.My question may seems like silly.But i want to know the reason.After that i was thinking about how the bike will run smoothly in night time, suddenly a thought strikes my mind,that is in my country night time is slightly cold.Bike engines mix the fuel and air for combustion.In day time the air in the surroundings will not be in cold condition it will be slightly hot.So the ignition is rough and in night time the air will be cold,so ignition process goes smoothly in night time.The mixing of fuel and cold air makes the bike to run smoothly.This is the idea that strikes my mind.Is it correct or not.If it is not correct then explain me what was the reason for the bike to run smoothly in night time.



I don't know what the temperature difference is there between day and night, but in general, it is possible. Air is more dense when it is cold, so the air fuel mixture might be able to burn. If the air is hot, the air fuel mixture might be too rich. Does your bike have black smoke in the exhaust during the day? I wouldn't think you're engine is that sensitive, but it's possible. You could try to lean out (lessen the amount of fuel being fed into the air) your carburator. This is usually done by screwing in the main jet or getting a main jet with a smaller hole. If you bike uses gasoline mixed with oil, I would be careful as you can lean it out too much which would starve the engine of lubrication and your engine would need costly repair.

vapor lock

am I the only one for whom the last letter, or punctuation gets cut off on this site? I try to remember to put a few spaces after a "?" or a ".". But my "?" got cut off on

"Vapor lock?".

your comment seems like not related to the subject

are you familiar with vapor lock? It is more likely to occur at higher ambient temps.

Are you more cautious and back off from the throttle at night?

throttle controls speed of an engine,then how can I back off from applying throttle?.Without applying throttle no one cannot drive


1 year ago

Do you own a Honda Shine? Anyways in day the density of fuel is less and at night the density of fuel is more and opposite for the vapour pressure in fuel tank ( I know that's not a correct term). That's why it is said to fuel up in early morning or late night.

This makes carburetor slightly off (only if it's not a CV carb). If you own a Honda Shine then get the air vent in your fuel tank lid cleaned and the throttle body and carburetor too.

One method to determine rich/lean status is to feed it some propane while it's running. If engine goes faster, it has been running lean. If it runs slower, it is rich, or balanced naturally.