entropy
Moderator
Posts: 8671
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posted September 06, 2006 04:30 AM
ign trigger on cam: how close does it have to be???
I am sure we have some folks who can shed light on this...
I recently rebuilt Buddy's 1375 after he had a rod sling thru the block & cases.
During the build I removed the trigger on the end of the exh cam, and THEN noticed that the orig builder had ground off the lil "tit" which sets the trigger position wrt cam lobe position. He apparently somehow had indexed the trigger for the cam/ECU model years, but didn't mark the "right" position.
Buddy messed with the position and got it to run but the question is "how close does it have to be to the exact position"??
What exactly does that trigger control? Is it degree for degree to ign timing?
How does it relate to the trigger which is on the end of the crank (cam chain driver)???
Any info wjould be much appreciated
Thanks!
Karl
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buddy
Expert Class
Posts: 335
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posted September 06, 2006 05:40 AM
Messed with it? I made a little jig out of solder and wrapped it around the trigger of a stock cam I have. It went around, over and had a pointer to point to a place on the lobe. I transferred the jig to the race cam and set the pointer to the same place. Messed with it? I think not! 
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entropy
Moderator
Posts: 8671
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posted September 06, 2006 05:55 AM
quote:
Messed with it? I made a little jig out of solder and wrapped it around the trigger of a stock cam I have. It went around, over and had a pointer to point to a place on the lobe. I transferred the jig to the race cam and set the pointer to the same place. Messed with it? I think not!
ALLRIGHT!!!
I KNEW you could figure it ou!!!
Now we just have to be extra careful to assure that close is close enough, especially with the load of juice you blast into that beast!
:thumbsup
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osti33
Needs a job
Posts: 2973
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posted September 06, 2006 02:23 PM
quote:
I am sure we have some folks who can shed light on this...
I recently rebuilt Buddy's 1375 after he had a rod sling thru the block & cases.
During the build I removed the trigger on the end of the exh cam, and THEN noticed that the orig builder had ground off the lil "tit" which sets the trigger position wrt cam lobe position. He apparently somehow had indexed the trigger for the cam/ECU model years, but didn't mark the "right" position.
Buddy messed with the position and got it to run but the question is "how close does it have to be to the exact position"??
What exactly does that trigger control? Is it degree for degree to ign timing?
How does it relate to the trigger which is on the end of the crank (cam chain driver)???
Any info wjould be much appreciated
Thanks!
Karl
Karl,
I don't think it can be degree for degree to ign timing since the cams go around only once for every two revolutions of the crank.
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kcadby
Pro
Posts: 1733
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posted September 09, 2006 08:24 PM
It doesn't have to be exact (deg-for-deg) or it wouldn't be posssible to degree the cams anything other than stock...right???
It tells the ECU when #1 is coming up on compression so the fuel and ignition can be fired sequentially on the proper stroke...
We found out how far you CAN'T move the Bbusa cam (INTAKE Cam where pin is on Bbusaz) before the bike wouldn't run right 
Started but ran like ass...we spent HOURS over 2-3??? nights trying to find what was WRONG with the bike because it had been ALL appart and had MANY new and different parts including the USB Ignition Module (motor wasn't even the same either) ...
Turned out our rather odd (was experimenting) Cam timing (that was done on bench before THIS motor had ever been started) "pissed off" the ECU...LOL...
ANYWAY...
Re-read my first sentance...IF yer memory is as good as mine 
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entropy
Moderator
Posts: 8671
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posted September 10, 2006 01:00 AM
KC,
thanks for the info. Yep, it couldn't be degree for degree as you point out.
Dave Owen scanned & sent me a page from the Busa workshop manual which shows exactly how the cam trigger and the ign trigger work together to provide info for the ECU to time the fuel & ignition. He had experienced a Busa which started but didn't make any hp, and eventually traced it to the cam trigger/sensor.
Good stuff!!!
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megabyte
Pro
Posts: 1047
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posted September 10, 2006 08:41 PM
quote:
Messed with it? I made a little jig out of solder and wrapped it around the trigger of a stock cam I have. It went around, over and had a pointer to point to a place on the lobe. I transferred the jig to the race cam and set the pointer to the same place. Messed with it? I think not!
Buddy,
How much did you pick up w/the Race Cam?
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buddy
Expert Class
Posts: 335
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posted September 11, 2006 06:56 AM
I never ran the motor without the race cams. It ran 5.62 on motor with the cams.
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