Motorcycle Quickshifter

Hi,

I am intending to make an ignition cut out module for a motorcycle using the arduino. The ardunio will basically cut the ignition coils so that the gear can be changed at full throttle (The ignition cut will take the load off the gearbox and allow the next gear to be selected).

I have not actually purchased anything yet, because I am confused about how to go about integrating the 12v electrics on the motorcycle and the 5v power of the arduino. I have a step down buck converter I can use to power the arduino via the Vin pin.

I have found a wire on the motorcycle I can cut (12v), once the circuit is broken this stops the coils from firing. I can connect a relay to this wire in a NC configuration and trigger it from an arduino output pin. I think this will work, however I need much faster switching than a mechanical relay can provide.

I have done a simulation of this here: https://circuits.io/circuits/2604466-quickshifter/

The bulb represents the ignition coils of the motorcycle and the push button will in reality be a microswitch or a proximity sensor on the gear linkage, it will sense when the gear is about to be changed. I have set the delay to 500ms, just for illistration purposed but in reality the ignition off time will be around 60ms. This is why the switching time is important.

I have been looking into solid state realys or a depletion mode MOSFET (possibly with NPN transistor as well?) to break the 12v circuit but I am not sure where to start. I have done a lot of reading and come to the conclusion that depletion mode MOFSETs are not widely used or very good.

So, I am looking for help on a circuit to make this work. I need it to be fast switching, faster than a mechanical relay. It will also be activated quite frequently. (It is used on a racing Motorcycle, when going up gears). Also, should the arduino fail, I need the 12v circuit to be closed.

I have been reading a thread on here: P-Channel mosfet controlling car 12v light - General Electronics - Arduino Forum Seems similar to what I need but I realise I have no idea about whether or not I need resistors coming from the arduino output pins and how to determine the correct size of the resistors also.

I have measured the current on the 12v circuit. It is around 2A maximum. I have not tested it when the engine is running close to full revs, I am not sure if it will change, the coils will be firing more often.

Thanks in advance for any guidance

Regards,
David

You have electronic ignition or magneto?

Won't there be a risk of backfrires with unburnt fuel in the exhaust manifold?

It is an electronic ignition. Honda CBR 600 RR. It is actually in a formula 2 racing sidecar, but the engine and electronics are taken from a motorcycle.

The wire I am cutting is a common wire that also goes to the injectors, so I believe that the fuel will also be stopped, so there should be no backfires. Flames out of the exhaust are cool though!

A lot of quickshifters work this way so I don't think unburnt fuel is a big problem.

flames.jpg886×637 41.1 KB

rickerman:
A lot of quickshifters work this way so I don't think unburnt fuel is a big problem.

Can you explain more ?

This sounds like a motor problem rather than an Arduino one.

rickerman:
Hi,

I have done a simulation of this here: https://circuits.io/circuits/2604466-quickshifter/

That link appears to lead back to this post, a bulb has very different characteristics to an ignition coil.

The picture with the flames is taken from my sidecar a few years ago when it had a quickshifter fitted. The strain gauge sensor was broken due to a "racing incident". I never had any problems with that quickshifter, just the occasional flames from the exhaust and occasional backfires. I can buy another sensor or make a switch myself (with a micro switch or proximity sensor) and my quickshifter will work again, as the ignition cutting functionality is contained in the ECU.

This post is about my brothers sidecar, his ECU does not have any provision for a quickshifter so I am trying to make a DIY one with the arduino. Commericial quickshifters that are avaiulable work in exactly this way, they connect inline with the ignition coils. I have attached a picture of a commercially available quickshifter. All I am trying to say is that I am not concerned about unburnt fuel.

Boardburner2:
That link appears to lead back to this post, a bulb has very different characteristics to an ignition coil.

I have attached a picture of the simulation.

I realise that ignition coils are very different to a light bulb. I was just using it as a test. I want to break a 12v circuit with a 5v signal recieved from the arduino. A bulb was just a way for me to simulate a closed circuit.

Capture.PNG1050×537 36.6 KB

rickerman:
Hi,

The bulb represents the ignition coils of the motorcycle and the push button will in reality be a microswitch or a proximity sensor on the gear linkage, it will sense when the gear is about to be changed. I have set the delay to 500ms, just for illistration purposed but in reality the ignition off time will be around 60ms. This is why the switching time is important.

So, I am looking for help on a circuit to make this work. I need it to be fast switching, faster than a mechanical relay. It will also be activated quite frequently. (It is used on a racing Motorcycle, when going up gears). Also, should the arduino fail, I need the 12v circuit to be closed.

I have been reading a thread on here: P-Channel mosfet controlling car 12v light - General Electronics - Arduino Forum Seems similar to what I need but I realise I have no idea about whether or not I need resistors coming from the arduino output pins and how to determine the correct size of the resistors also.

I have measured the current on the 12v circuit. It is around 2A maximum. I have not tested it when the engine is running close to full revs, I am not sure if it will change, the coils will be firing more often.

Regards,
David

It sounds like a job for a relay.
They can be had with on times of less than 10 mS but switching current may be a problem.
If the coil is not taking current at the time the relay operates then contact arcing should not be a problem so long as the contacts can take the operating current when closed.

Sorry not that familiar with what you are trying to do though.

I am not a engine person so this might be a dumb question:

If the engine is running and you cut the ignition to shift, won't the engine stop running ?
Does it restart automatically just like pushing a car and popping the clutch ?

The engine has inertia. It stops accelerating when the fuel or ignition is cut. But it doesn't immediately stop spinning and throw you over the handlebars like a cartoon.

This is also only a very brief cut. Maybe 1/10th of a second. Just enough to get it out of gear and then the motor slows down to pick up the next gear.

Is this similar to what Honda call their Speedtronic transmission system ?

(Can be driven manually with paddles.)

Since you're operating the gearshift at the same time as you want the engine to cut, why not just fit a push -to-break switch in the power line to the coils?

regards

Allan.

and throw you over the handlebars like a cartoon.

been there, done that, on a Yamaha FJ-1100 , when I got sandwiched in between two cars and the car on the right was a late model white Cadillac. The driver heard my handlebar scraping the paint on his door so he punched the accelerator creating a large speed differential between the car on left and the car on the right, causing the front wheel of my motorcycle to jam all the way to left with no way for the motorcycle to fall down (being sandwiched) so the front wheel could not rotate so it acted like the front brake was locked up , abruptly decelerating the bike and launching me over the handlebars. It's true what they say about time standing still in a moment of crisis because while I was still airborn I was able to think that I should do a Judo roll when I hit the ground to avoid breaking every bone in my body. I actually did just that and , thanks to the helmet and leather apparel, was able to drive the bike home with only the rear brake functioning, instead of waking up in the hospital. That was a one of my worse days on 2-wheels,
surpassing the time I hit transmission fluid on a curve while canyon racing in Topanga Canyon in Southern California (USA). That, by comparison, was just another day at the office.

allanhurst:
Since you're operating the gearshift at the same time as you want the engine to cut, why not just fit a push -to-break switch in the power line to the coils?

regards

Allan.

Because I want the time of the ignition to be cut to be controlled by the arduino. As I need the ignition to be cut for as little time as possible. We are talking about 60-100 ms.

I'm beginning to think that I need a solid state relay for this to work effectively. I don't understand enough about MOFSETs to make a working circuit.

I need to do a current test when the engine is running at full speed. I'm not sure if more current will be drawn if the coils are firing more often.

A lot of the 5v solid state realys I can find come on a board with other components. What are these extra components? Can I not just buy a SSR and hook it up to the load and arduino output pin?

Regards,
David

Make sure to buy a DC SSR ( not AC)

Whats the difference between these 2?

http://www.ebay.co.uk/itm/1-pc-GJ-5FA-L-DC-DC-PCB-SSR-In-3-32VDC-Out-5-220V-DC-5A-Solid-State-Relay-/361458810235?hash=item54289fbd7b:g:orwAAOSwNyFWg~Dh

http://www.ebay.co.uk/itm/1pc-1-Channel-SSR-Solid-State-Relay-High-low-Trigger-5A-3-32V-For-Arduino-Uno-R3-/231742565205?hash=item35f4eeeb55:g:rMAAAOSwI-BWOHRz

I have been watching this video: Optocoupler MOSFET based DC Relays Using Photovoltaic Drivers - YouTube

This looks like it could be what I need.

However, I am confused as to how I can connect the Drain of the MOSFET to my already complete 12v circuit. I need to break into the +ve feed of the 12v circuit. The MOSFET would need to break this circuit when it is activated.

What you are describing is a high side switch. Without the motorcycle schematic it is uncertain whether you need a high side or low side switch.
High side uses P-channel , low side uses N-channel.