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Discussion Starter #1
Santa's bringing me one of these this year!


I'm going to play around with it. The unit has two tables that can be selected via a switch.
I'm going to set one table to match the factory spark advance (as a fallback if anything goes wrong while riding).
The second table will be a custom table.

It also has a global retard option that I can switch on/off. I'm going to use it to advance the ignition for premium fuel, and retard back for regular.
It will add a RPM limiter, and an optional shift light (just a little LED I'll tack on somewhere).

I'm adding a MAP sensor to measure carb vacuum and I'm going to advance based off engine vacuum.
I'm planning on linking the two carb vacuum ports to provide a more steady signal to the MAP sensor.
I'm adding T fittings to run to the petcock, the air bypass system, and the MAP sensor off the linked vacuum line.

This carb linking is going to be interesting. At idle, the carb will be able to draw through it's own throttle plate as well as the opposite carb's throttle plate. At least it will be a proper mixture either way. But I expect it to appear like a larger throttle opening than I actually have. Hopefully that only means I readjust the idle. On the other hand, the air in the linking tube might just oscillate back and forth and have minimal effect. At WOT, I don't see it having much effect. The vast majority of air will be drawn through the local carb body, with only a small amount drawn through the opposite carb. This I can test without changing ignition just by rerouting the hoses.

Once I have a working tune, I'll post my settings file online for others to use.
At the very least, this unit would make for a replacement ignition module if someone's original unit failed.
It's under $200 with custom wiring for this bike.
 

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Looks like quite an experiment. Get it working then you can try a nitrous bottle on it. 😈

Have you read the vacuum on one of the carbs yet? I expect there's no pulsing on a good engine, (at least above idle) so tying the vac lines together might not be needed.

Never had a vac gauge on mine, so I'm not sure, just thinking out loud.

You'd be a good candidate to test the white/red mystery wire on the CDI. 🤔 I think you could just flash the timing light and hit the start button while idling, see if the timing advances or retards. Starter clutch will prevent engagement of the starter.
 

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Discussion Starter #3
Looks like quite an experiment. Get it working then you can try a nitrous bottle on it. 😈

Have you read the vacuum on one of the carbs yet? I expect there's no pulsing on a good engine, (at least above idle) so tying the vac lines together might not be needed.

Never had a vac gauge on mine, so I'm not sure, just thinking out loud.
I had vacuum gages on the carbs when syncing. They required I adjust the valves on the gauges to keep the needle steady. Otherwise they bounced terribly! That might have just been the gauges I was using.

When running, each carb only pulls vacuum for 1/2 a revolution, and then has no action for 1 1/2 revolutions. I would imagine during that time that the vacuum would leak down through the throttle plate. I really ought to invest in a vacuum gauge to see what it's doing.

You'd be a good candidate to test the white/red mystery wire on the CDI. 🤔 I think you could just flash the timing light and hit the start button while idling, see if the timing advances or retards. Starter clutch will prevent engagement of the starter.
This has been bugging you for awhile, hasn't it! ;) I'll check it out while I'm at it.
 

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Discussion Starter #4
Guess what arrived today???
52850
 

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Yes it has been, I attribute that to it being winter. I did get a short ride in today. It was a balmy 44 degrees today.

Fascinating little gadget you have there. Curious to see how it works for you.
 

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Discussion Starter #8
My first goal is to get it running on a stock ignition table to verify I have everything installed/configured correctly. I have a few more parameters to set/adjust before I can install it.
1. I need to measure the angle difference between the pick-up coil and the target on the crankshaft (Base Advance).
2. I need to measure the coil dwell time (the time the coils charge up before each spark) on the stock system. The TCIP4 manual says to use one setting for < 2 ohm coils and another for > 2 ohm coils. The VN750 manual says the coils are 1.8-2.2 ohms, so I'm not sure what setting to use!!!
3. I need to transfer my safety cut out circuit over to the ground side of the ignition coil relay.

Then we experiment, and slowly make changes to the system.
1. Run the new ignition with a stock ignition curve to see if it runs properly. Check timing with timing light. Oil splatters everywhere! ICK!
2. Tie the two carb vacuum ports together to see if that affects how it runs. <-- This step alone will be quite interesting information for this bike! Some VW Beetle owners do this to smooth out their idle. I'm curious what it will do to the VN750.
3. Add in the MAP sensor and verify I have readings that make sense. I should be able to sync the carbs with the MAP sensor and a clothes pin, cutting off the sensor from each carb at a time.
4. Add my switches to toggle between stock and modified timing curves, and global retard (turned off for premium fuel).
5. Add a shift LED. Just for fun! :)
6. Get a few rides in to find some common cruise RPM and MAP readings. I'll have to wait for some warmer weather for this :( I'd like to cruise at 30 - 90 in 5th gear, holding at every 10, to find what RPM and MAP readings I get at those speeds. I also want to grab a WOT run in 3rd out to 8500 RPM and a closed throttle decel back down to idle, to see what I get for MAP readings at the extremes.
7. Rent time on a dyno, and tune those points for best response.
8. Upload my tuning file for others to use.
9. Enjoy the ride!
10. Post my impressions a few months later.

1-5 I can do before spring. 6-10 are going to have to wait for a bit.

52852
 

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I'll be watching this with interest for sure. I salute you from the peanut-gallery.
Don't forget to hit that start button with the stock IC plugged while you're slinging oil around to see if it does anything to the timing!
 

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Discussion Starter #10
I measured the coil dwell time. The first picture shows 50.3mS between sparks (1,193 RPM).
52868

This image shows a coil dwell time of 14.3mS.
52869

The portion where the current stops rising and goes flat means excess dwell time. That causes extra heat in the ignition coils. So it looks like 8-9mS is all that's needed.
52870

At high RPM, I had some interference. This is 7,998 RPM.
52871

At this high RPM, the dwell is cut down to 2.662mS. So this shows that at high RPM, the spark energy is only about 1/4 of what it is at idle.
52872

When I measured the base advance, I lined up 5 degrees BTDC.
52873

The coil pick up was right at the edge of the target on the crankshaft.
52874
 

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Discussion Starter #11
I put this info into the progammable controller, along with the stock advance (5 at 1,100 to 25 at 3,500). I plugged it in and she fired right up!

I checked the timing on the stock controller and the programmable controller and they both match! No need to spray any more oil.

On the stock controller, I didn't see any change with pressing the start button. So the Red/White wire purpose is still a mystery!

I put several Ts in the vacuum lines, so the two carbs are linked with the MAP sensor between them. Linking them makes it behave just a bit different. Higher idle and a bit of rev hang. I might have to readjust the idle mixture screws.

I tested the rev limiter by setting it to 5,000. It works well! When it kicks in, the tach goes nuts trying to match the missing sparks. But the revs hold steady. I reset the limiter to 8,500.
 

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Nice job on the swap. That'll be a huge boon to people looking to swap out their igniter.
I really need to make friends with an electrical engineer and have them figure out what that input is from the start button. I wonder if we could track down the original engineer at Kawasaki? XD
 

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It’s always a good time when you break out the O-scope! Really cool info. I read before that spark cuts down as RPMs increase, awesome to see the science illustrated. I have an old scope from tech school, I may try this someday to see how the bike matches up to your findings.

Great work!
 

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Discussion Starter #14
Here is the new controller, stuffed on top of the battery.
52875

Here's the connections. I tapped into the safety cutoff line (Neutral, Clutch, Kickstand) to run it to the negative side of my direct coil relay.
52876

The programming connection sits just under the seat and frame on the right side.
52880

T fitting on left side of the bike. The additional hose crosses over to the right side.
52877

The two T fittings on the right side. This ties the two vacuum ports together, and Ts off to the vacuum sensor. The vacuum sensor uses 1/8" line, so there is a brass size changer towards the top left of the picture.
52878

The vacuum sensor (three wires) is tucked behind the engine, with the hose routed over top the rear cylinder.
52879


All electrical connections are reversible on the road. If you look carefully in the second picture, the original controller is still in its stock location. Should I ever have a problem, I can return to the stock controller in just minutes. I'll have to ride it to see how the conjoined carbs feels.

When I am all said and done here, I'll upload my tuning file. It's going to have both a stock (no vacuum sensor) tuning and a modified tuning. I'm going to only run stock until I can get on a dyno.
 

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Discussion Starter #15
Just in case something happens and I never get back to this, here is my tuning file as of this past Saturday. This can be used as a stock ignition controller replacement. HOWEVER, it does NOT include the safety cut-off switches (Neutral, Side stand, Clutch).

This tuning file has an alternate table that is NOT tested, that is enabled by grounding the new controller's pin 8. It has a rev limiter programmed to 8,500 RPM, a shift light (PIN 3) at 8,000 RPM, and a MAP sensor (Pins 6, 16, & 17). The MAP sensor is ignored for the stock table.

Other than the safety cut-off switches, this is a plug and play replacement. Just rename the file to .ign in order to use.
 

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