Jackyl71
07-10-2015, 02:21 AM
So I was pretty happy when I solved my spark issue on my ATC70 the other day... Now came time to put some gas to it and see if it would fire!
I installed a new Chinese carb, gassed it up, flipped the choke, and pulled away for a few minutes with NO results... No sputter, no popping, no running - nothing.
SO I figured fuel problem. Cheap carb must be junk. I swapped out for the one that came with the trike when I bought it, and tried it again, and still nothing.
Hmmm...
Pulled the carb, and just for test purposes, dripped a little gas directly into the intake and pulled. I got a POP and a backflash into the intake (nothing big, but a little flame. And no damage or anything). But after that I noticed something. When I would pull with the started and look into the intake, I could see the spark! And that means that the intake valve was still open when the plug was firing...
So here are my questions to the Forum:
1) Does my 70's plug fire once per revolution? In other words, it fires at the top of the compression stroke (normal), as well as at the top of the exhaust stroke (wasted spark)? I am guessing YES, as this isn't the most sophisticated ignition system.
And 2) If so, the fact that I can see the spark through the intake while the intake valve is still open (presumably the wasted spark - or else there is something much worse going on here), is my timing too far advanced (sparking late, after the valve opens)? Do I need to retard it so it sparks before the intake opens to draw fresh fuel into the cylinder?
The reason I am asking about the timing is because I originally set my timing using the "Static Timing Adjustment" method, and per everything I have read and watched, I should be set dead-nuts (the light dimmed EXACTLY when the FIRE mark on the flywheel hit the alignment mark on the engine case). Could the timing be set just right using this method, but still not set right to actually make the trike run?
Should I be looking for another culprit?
As always, thanks for any help of information you all can provide.
Jackyl71
I installed a new Chinese carb, gassed it up, flipped the choke, and pulled away for a few minutes with NO results... No sputter, no popping, no running - nothing.
SO I figured fuel problem. Cheap carb must be junk. I swapped out for the one that came with the trike when I bought it, and tried it again, and still nothing.
Hmmm...
Pulled the carb, and just for test purposes, dripped a little gas directly into the intake and pulled. I got a POP and a backflash into the intake (nothing big, but a little flame. And no damage or anything). But after that I noticed something. When I would pull with the started and look into the intake, I could see the spark! And that means that the intake valve was still open when the plug was firing...
So here are my questions to the Forum:
1) Does my 70's plug fire once per revolution? In other words, it fires at the top of the compression stroke (normal), as well as at the top of the exhaust stroke (wasted spark)? I am guessing YES, as this isn't the most sophisticated ignition system.
And 2) If so, the fact that I can see the spark through the intake while the intake valve is still open (presumably the wasted spark - or else there is something much worse going on here), is my timing too far advanced (sparking late, after the valve opens)? Do I need to retard it so it sparks before the intake opens to draw fresh fuel into the cylinder?
The reason I am asking about the timing is because I originally set my timing using the "Static Timing Adjustment" method, and per everything I have read and watched, I should be set dead-nuts (the light dimmed EXACTLY when the FIRE mark on the flywheel hit the alignment mark on the engine case). Could the timing be set just right using this method, but still not set right to actually make the trike run?
Should I be looking for another culprit?
As always, thanks for any help of information you all can provide.
Jackyl71