Y bike hard to start after a stationary drop?

[Guest alxfoo]

Hi all, today i had a stationary drop while the engine was running. After i turn off the engine and carry up the bike, the bike was super hard to start again. I had to keep pressing the starter and keep throttling. After more then 10 tries, the bike suddenly started with a very high rpm. Was there any dmg to the bike?

[Raptor]

For a carburated bike... the engine will get flooded with petrol when the bike is tipped over. The carb float bowl is designed to work with the carb in the upright position but will not stop fuel flow from the tank if it is not in the upright position.

 

The fastest way to restart a flooded engine is to hold the throttle wide open (to allow more air to go in during the cranking to dry up the fuel) during the starting.

 

Trying to start the bike normally will result in slow drying up of the cylinder which means more starting cycles, just like what happened to you.

 

When you crash alot of times like me on the tracks... you will learn that this is the best and fastest way to restart a bike after its been down.

[Guest alxfoo]

Thanks for the tips! Anyone knows any shop that does small paint job to cover few scatches? And what is the cost?

[JackOHJack]

For a carburated bike... the engine will get flooded with petrol when the bike is tipped over. The carb float bowl is designed to work with the carb in the upright position but will not stop fuel flow from the tank if it is not in the upright position.

 

The fastest way to restart a flooded engine is to hold the throttle wide open (to allow more air to go in during the cranking to dry up the fuel) during the starting.

 

Trying to start the bike normally will result in slow drying up of the cylinder which means more starting cycles, just like what happened to you.

 

When you crash alot of times like me on the tracks... you will learn that this is the best and fastest way to restart a bike after its been down.

 

Whoa! Now that is something they dun teach us in driving schools!

[chuan.z]

For a carburated bike... the engine will get flooded with petrol when the bike is tipped over. The carb float bowl is designed to work with the carb in the upright position but will not stop fuel flow from the tank if it is not in the upright position.

 

The fastest way to restart a flooded engine is to hold the throttle wide open (to allow more air to go in during the cranking to dry up the fuel) during the starting.

 

Trying to start the bike normally will result in slow drying up of the cylinder which means more starting cycles, just like what happened to you.

 

When you crash alot of times like me on the tracks... you will learn that this is the best and fastest way to restart a bike after its been down.

 

Noob qn: wouldn't holding the throttle wide open flood the carb even more? Or is it have to turn the fuel petcock to OFF position first?

[GuiNNeSS]

nope, what raptor said is tried and proven

 

i do that oso.

[Raptor]

Noob qn: wouldn't holding the throttle wide open flood the carb even more? Or is it have to turn the fuel petcock to OFF position first?

 

Cranking the engine with the starter or kick starter does not turn the engine at normal idling rpms... its very low.

 

Because of the low flow of air through the carb even though the throttle is held wide open... the fuel cannot be drawn up through the main jet. This means there is more air going into the engine than fuel.

 

When the engine is flooded with fuel (as a result of the tip over).. combustion does not occur since the fuel mixture is way too rich for the spark to ignite. By holding the throttle wide open while starting... fresh air is drawn in to dry up the combustion chamber until the air/fuel mixture is of the correct ratio and then ignition can occur.

 

The bike will stutter and slowly fire up as the mixture becomes correct.

[queirtus]

Cranking the engine with the starter or kick starter does not turn the engine at normal idling rpms... its very low.

 

Because of the low flow of air through the carb even though the throttle is held wide open... the fuel cannot be drawn up through the main jet. This means there is more air going into the engine than fuel.

 

When the engine is flooded with fuel (as a result of the tip over).. combustion does not occur since the fuel mixture is way too rich for the spark to ignite. By holding the throttle wide open while starting... fresh air is drawn in to dry up the combustion chamber until the air/fuel mixture is of the correct ratio and then ignition can occur.

 

The bike will stutter and slowly fire up as the mixture becomes correct.

 

but does it apply to 4 stroke or 2 stroke bikes?

[xiaobanz]

Wow i really didn't know that.. No wonder that time i drop my super four and thought i dmg the engine cos cannot start...

[Raptor]

but does it apply to 4 stroke or 2 stroke bikes?

 

Both are the same.. as long as it has got a carb.

 

For fuel injected bikes like the CBR1000RR I used to have... there is an overcentre sensor. Once the bike is tipped over, the sensor will cut ignition and fuel pump.

 

To fire up the bike again... I had to turn the ignition off then on again to reset the sensor. Or else you can crank the engine till the cows come home and the battery go flat and it still won't start.

[kurarensu]

great info.. learnt alot frm raptor by jus reading these few post..

 

this shld be sticky mans aha

[zyrofillica]

usually ill close the fuel petcock and then kickstart with full throttle. Once engine roars to life release throttle open petcock. This is usual practice for 2stroke scram after a drop.

[chuan.z]

Cranking the engine with the starter or kick starter does not turn the engine at normal idling rpms... its very low.

 

Because of the low flow of air through the carb even though the throttle is held wide open... the fuel cannot be drawn up through the main jet. This means there is more air going into the engine than fuel.

 

When the engine is flooded with fuel (as a result of the tip over).. combustion does not occur since the fuel mixture is way too rich for the spark to ignite. By holding the throttle wide open while starting... fresh air is drawn in to dry up the combustion chamber until the air/fuel mixture is of the correct ratio and then ignition can occur.

 

The bike will stutter and slowly fire up as the mixture becomes correct.

 

Oooh. Now it makes sense! Great piece of info

[pixeLFreak]

good info by Raptor.

 

another way is to clean the flooded plugs tip.

[austinlim]

Both are the same.. as long as it has got a carb.

 

For fuel injected bikes like the CBR1000RR I used to have... there is an overcentre sensor. Once the bike is tipped over, the sensor will cut ignition and fuel pump.

 

To fire up the bike again... I had to turn the ignition off then on again to reset the sensor. Or else you can crank the engine till the cows come home and the battery go flat and it still won't start.

 

on/off the kill switch twice as stated in the user manual of CBR1000RR, this will overwrite the overcenter sensor...