cough with with fuel injected

[Fallguy]

I have had the bike on the trickle charger for the better part of the last 3 weeks due to so much work and then rain. Had to ride today no matter what except was only for 30 minutes .. woohoo .. Anyway , at start on first turn-over it just coughed and on second turned right over and then idled fine.. Can anyone explain why it coughed or is it just a haven't run in 3 weeks thing ??

 

[bugdewde]

Usually, that cough is when the engine fails to fire off to continue the 4 cycles of internal combustion.
When the rotating mass doesn't get enough inertia to continue rotating (no ignition of fuel mix), it will stop rotating, usually before the high compression stroke.

In your case (probably), the inertia was just enough to get the rotating assembly into the compression stroke (blind luck) and the compressed, unburnt fuel mix was released either out the intake or sometimes the exhaust, depending on cam/valve overlap position.

In a nutshell, you didn't engage the electrical starting motor enough to complete the ignition process. Quite normal.

On a kick start Harley (and other bikes), that compression stroke would kick the starter lever back up, sometimes throwing your shin into the foot peg or even kick you in the back of the leg/knee if you didn't have a heel on your shoe to hold the kick starter on your shoe.

Electric start motorcycles are for "wussies" with a "P".......... Says my old Shovelhead buddies.

 

[BIKERSARGE]

Well said

Well said

Usually, that cough is when the engine fails to fire off to continue the 4 cycles of internal combustion.
When the rotating mass doesn't get enough inertia to continue rotating (no ignition of fuel mix), it will stop rotating, usually before the high compression stroke.

In your case (probably), the inertia was just enough to get the rotating assembly into the compression stroke (blind luck) and the compressed, unburnt fuel mix was released either out the intake or sometimes the exhaust, depending on cam/valve overlap position.

In a nutshell, you didn't engage the electrical starting motor enough to complete the ignition process. Quite normal.

On a kick start Harley (and other bikes), that compression stroke would kick the starter lever back up, sometimes throwing your shin into the foot peg or even kick you in the back of the leg/knee if you didn't have a heel on your shoe to hold the kick starter on your shoe.

Electric start motorcycles are for "wussies" with a "P".......... Says my old Shovelhead buddies.

Now that was well said

 

[Fallguy]

Thanks for the good explanation.. My Springer was an 02 carb 88ci and had 11 years to get used to it..There were no surprises there.