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Syncing carbs using two MAP sensors? (Read 250 times)
N8
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Syncing carbs using two MAP sensors?
Jun 12th, 2014 at 5:02am
 
Hey everyone, thinking of trying to use two MAP sensors two sync up my carbs on my 1994 Honda Shadow VT600.  What are your thoughts?  Will the signal be clear enough to use as a sync tool?
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Daniel
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Re: Syncing carbs using two MAP sensors?
Reply #1 - Jun 13th, 2014 at 9:48am
 
Great idea, let’s see some captures.  Smiley
This VFR was out of sync.
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N8
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Re: Syncing carbs using two MAP sensors?
Reply #2 - Jun 13th, 2014 at 11:11am
 
I'll have t find some MAP's with harnesses, but I'll try it since its starting to slow down in the shop, I can play around again with the scope
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Olly
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Re: Syncing carbs using two MAP sensors?
Reply #3 - Oct 15th, 2014 at 7:24pm
 
Daniel wrote on Jun 13th, 2014 at 9:48am:
Great idea, let’s see some captures.  Smiley
This VFR was out of sync.


Can someone show me here how to identify where this one is out of sync, I'm stuggling with it a little.

Cheers Smiley
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StitchB
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Re: Syncing carbs using two MAP sensors?
Reply #4 - Jan 10th, 2015 at 5:43am
 
Here is an idea but not with MAPS. Does require some butchering but in the long run good.   Place and O2 sensor in each exhaust stack and shoot for 1/2V.

As stated have never done but would  Buy a couple cheap o2's

Have never done this but read about it and makes perfect sense.

When I read it I thought that is about as exact as you can get. My thought is even reading intake volume on a multi cyclinder volume of intake as sometimes they are separated, may not actually be synced as far as power produced due to wear variations. Is actually what an ECM does regulating injector volume to accommodate different cylinder pressures.

Hooked my Pico up to My KLR 650 and was surprised to see that the coil is AC 120 volt as that side of the alternator is not converted through diodes down to DC and would never have caught it except it was not 12 volt supply but 120 AV.  Coil is about the size of a roll of dimes as volts times amps is watts and if the supply is almost 10 times higher you don't need as large of unit.  Ignition from coil looks like a screw rather than a wave jumping up from ground, strange.

Regards Larry
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Olly
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Re: Syncing carbs using two MAP sensors?
Reply #5 - Jan 10th, 2015 at 1:10pm
 
StitchB wrote on Jan 10th, 2015 at 5:43am:
Ignition from coil looks like a screw rather than a wave jumping up from ground, strange.


I find allot of the bike systems i come across look a little like what you are describing. Mostly on the carbeurated bikes with a CDI type ignition system.

StitchB wrote on Jan 10th, 2015 at 5:43am:
Hooked my Pico up to My KLR 650 and was surprised to see that the coil is AC 120 volt as that side of the alternator is not converted through diodes down to DC and would never have caught it except it was not 12 volt supply but 120 AV.



I believe this is probably a CDI type of system where by the coil is excited by a large & short release of voltage from the capacitior in the CDI ignitor unit. Rapidly creating a field in the primary windings.

Rather than the typical Transistorised type Ignition controll where by 12v is constant to the coil and the computer rapidly switches to ground to collapse the magnetic field.

I have found that on most bikes around a 200 peak voltage signal is normal minimum at idle going up to over 400v on some.

As for balancing with O2 sensors i would assume you could get a good result form testing this way. my only concern would be that alot of bikes have a cold air bleed into the exhaust for emmision controll in the exhaust port (which is a mechaincal type valve that opens) so you may well end up balancign to compensate for tollerances in that system also which shouldnt play a part in the combustion process.

But other than the issues of mounting the sensors i cant see why you couldnt get as good or arguably a better result this way. It would be good to try this and run it against a Map waveform and see if there is any noticable difference in the accuracy.
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Re: Syncing carbs using two MAP sensors?
Reply #6 - Jan 11th, 2015 at 7:08am
 
Olly, yes the bike is a CDI so would concur with what you stated.
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