How often do the coils spark?
03-11-2010, 08:02 PM
#1
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How often do the coils spark?
I had a reading on my timing light (which has a tach function) that was double what the bike's tach was saying. Do the coils fire on both the compression and the exhaust stroke?I'm getting ready to install to install some #48 pilots and wanted to dial them in with the 50 RPM instructions in the manual.
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03-11-2010, 08:17 PM
#2
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you know I haven't seen anything in the book, and normally I would say no, seeings how it has a coil per cylinder, and I know the converter has two separate wires being grounded by the ICM, but I found the same issue when I tried hooking up another tachometer from a different bike. So I would hazard a guess and say yes it's waste spark for some reason.
03-11-2010, 08:22 PM
#4
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Wah? Is his a trick question? We don't have twin-fire coils I believe. So the coils fire every 1,440 degrees of rotation or 1 time for every 4 rpm, thus divide by 4, or 2 if the TL reading is double the VTR's tacho. I presume you are also synchronizing (balancing) the carbs but its hard on the VTR because of its huge carbs to get an appreciable RPM change using the pilot circuit fuel screw and the VTR won't run down at 50 RPM anyway. However, none of the jets (pilot, main or air) don't care what RPM the engine turns... Dropping the revs using the idle fuel screw to 500~600 rpm is low enough to sync; also check balance at 4~5k revs. Set the fuel screws to 2-1/2 turns out +/- a 1/4 turn and fugetaboutit.
I had a reading on my timing light (which has a tach function) that was double what the bike's tach was saying. Do the coils fire on both the compression and the exhaust stroke?I'm getting ready to install to install some #48 pilots and wanted to dial them in with the 50 RPM instructions in the manual.
Thanks
Thanks
03-11-2010, 10:00 PM
#6
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Wah? Is his a trick question? We don't have twin-fire coils I believe. So the coils fire every 1,440 degrees of rotation or 1 time for every 4 rpm, thus divide by 4, or 2 if the TL reading is double the VTR's tacho. I presume you are also synchronizing (balancing) the carbs but its hard on the VTR because of its huge carbs to get an appreciable RPM change using the pilot circuit fuel screw and the VTR won't run down at 50 RPM anyway. However, none of the jets (pilot, main or air) don't care what RPM the engine turns... Dropping the revs using the idle fuel screw to 500~600 rpm is low enough to sync; also check balance at 4~5k revs. Set the fuel screws to 2-1/2 turns out +/- a 1/4 turn and fugetaboutit.
Now for the 50rpm mentioned, You set the pilots by turning them in until you get a 50 rpm drop and then you open them 1\2 turn.
03-12-2010, 05:08 AM
#7
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Wah? Is his a trick question? We don't have twin-fire coils I believe. So the coils fire every 1,440 degrees of rotation or 1 time for every 4 rpm, thus divide by 4, or 2 if the TL reading is double the VTR's tacho. I presume you are also synchronizing (balancing) the carbs but its hard on the VTR because of its huge carbs to get an appreciable RPM change using the pilot circuit fuel screw and the VTR won't run down at 50 RPM anyway. However, none of the jets (pilot, main or air) don't care what RPM the engine turns... Dropping the revs using the idle fuel screw to 500~600 rpm is low enough to sync; also check balance at 4~5k revs. Set the fuel screws to 2-1/2 turns out +/- a 1/4 turn and fugetaboutit.
03-12-2010, 06:53 AM
#9
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I didn't see anything either, nor did a search here turn anything up. My timing light doesn't like the multi-spark system I have on the Healey and at first, that's what I figured the hawk had. Talking to a friend about it, he mentioned his Harley triggers a spark every time the piston approaches TDC.
03-12-2010, 08:52 AM
#13
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You kind of lost me on some of this..... The VTR uses a wasted spark system. The easiest way to prove this is to look at the cam installation procedure. You set the timing mark on the flywheel to TDC of the cylinder you are setting but there is no mention of checking the ignition rotor position because it doesn't matter.
Now for the 50rpm mentioned, You set the pilots by turning them in until you get a 50 rpm drop and then you open them 1\2 turn.
Now for the 50rpm mentioned, You set the pilots by turning them in until you get a 50 rpm drop and then you open them 1\2 turn.
yep
03-12-2010, 10:15 AM
#14
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That's my main problem with the #45's, I have what feels like a lean spot just as I open the throttle. I have the pilots out about 3¼ to 3½ turns now. I have a Dynajet w/K&N and Micron exhaust to stir the pot also.
Last edited by Gregw; 03-12-2010 at 11:29 AM.
03-12-2010, 11:11 AM
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I think you missed the point I was trying to make. If this was a single fire motor, you would not only need to know the cylinder was at TDC but also the position of ignition rotor. Which you would need to know in order for the cylinder to fire at TDC on the compression stroke.
The fact that it doesn't matter what position the ignition rotor is in tells me that the coils fire every time the motor reaches TDC or a wasted spark ignition.
Yes I know the motor doesn't fire exactly at TDC it is a example before anyone get to picky.....lol
The fact that it doesn't matter what position the ignition rotor is in tells me that the coils fire every time the motor reaches TDC or a wasted spark ignition.
Yes I know the motor doesn't fire exactly at TDC it is a example before anyone get to picky.....lol
03-12-2010, 11:15 AM
#17
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