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#52049
Hey, my latst project idea is to efi convert a yamaha 1988 FZR250. For those unfamiliar, this bike is a 4 cylinder 250cc motor that redlines at around 18,500rpm. So obviously this makes it a bit of a challenge with such small cylinders (62.5cc) in regards to finding itbs etc. The main questions I have is about the speeduino capabilities however.

1- how will the software/hardware handle such a high rpm? Is there a known limit to how quick this computer can run an engine?

2- the fzr has an 'EXUP' valve which is just a large valve in the exhaust which creates backpressure at low rpm. Its controlled using a stepper motor from the factory. Is there a way to get that to be controlled? Possibly involving editing the base code in the arduino ide? The valve starts opening around 4krpm and is fully open around 10krpm.

3- i want to develop my own PNP board, because things aren't complex enough already :lol: . Mainly though because I think I can make the package smaller to fit in the limited space. With the high rpm, I'm concerned with heat build up from the MOSFETs. Anyone got some insights? Also any particular protocol for wire routing on the pcb to avoid unwanted noise etc?

At this point the first step would be to control the ignition first before tackling the fuel side. Few more things are, bike runs wasted spark and pick-up is a VR sensor so obviously will need conditioner. Can this be integrated into the motherboard or just buy a module?
Cheers
#52051
1. Not a problem. Just use a 24-1 or lower toothed wheel. RPM isn't an issue. Input frequency is. Mega tops out around 9khz range from memory.

2. Can't do. Not easily. If it was PWM then could use the VVT table.

Just have it open permanently. The CBR's of that era didn't run a valve and ran fine.

3 what mosfets do you expect to "heat up"?

There won't be any heat created at all basically. Ignition module though would be separate ideally as they are noisy.

You can integrate or use module. It's your project. You can build it as you wish.
#52056
Great, thanks. In regards to the valve, although it does run fine without, it runs better with it. Although the vvt pwm sounds promising, if I added another bit of circuit to convert the signal around a bit. In regards to mosfets, I've had them get very hot in past projects with pwm, however that was a large load being switched. Thanks for the advice
#52058
Hi neoncrypnid,
Actually I use a 2 stroke motorcycle (177cc) everyday with a NO2C fitted..

1- NO2C with 12-1 trigger wheel has been tested up to 12k rpm, I have some sync loss issues sometimes when changing gear without clutch. Everything is about the quality of the sensor, of the trigger wheel, of the resistors used on the vr conditioner and on the filter set on tunerstudio..
2-I don't tried it, but I think with VVT control it can be possible. I'm also interested in because I should run no2c on a rotax 122 with exhaust valve.
3-have you considered the NO2C PCB?
4-integrating everything on the MoBo means not being able to replace a single module anymore if it gets damaged, like the vr conditioner (personal opinion)
#52059
Rather than modify the main speedy firmware I would look at using a nano or mini (328p) type board (or teensy if you prefer) to drive the stepper for the exup valve based on the signal from the vvt output.
Are you sure it is a stepper? I know some had a drive unit attached to the valve mech via two drive cables. That motor unit was actually a motor with potentiometer feedback and operated like a servo(think RC) when added to the correct controller .
#52064
I'm planning to use the existing pick-up coil but at this point the project is still in the hypothetical stage so I can always change this, and since the stock cdi works with this sensor im hoping this will be adequate.

NO2C board does look good, I'd missed that on my scan of the wiki. I'm still tempted to make my own board just for the experience.

Thats a solid idea using a nano or similar to run the valve, ill definitely try to get that going.
You might be right about the motor that controls the valve. I've got one sitting around but never got around to installing it. Another thing to look into...
#52103
dazq wrote:
Tue Jul 27, 2021 8:25 am
That motor unit was actually a motor with potentiometer feedback and operated like a servo(think RC) when added to the correct controller .
I saw an exhaust valve opereted by a RC Servo on a Yamaha RX engine with a cylinder swap, by two wire, but is possible to use an RC servo directly with speeduino?

maybe it is OT but can be useful also for the author
#52104
danizichi wrote:
Wed Jul 28, 2021 12:32 pm
dazq wrote:
Tue Jul 27, 2021 8:25 am
That motor unit was actually a motor with potentiometer feedback and operated like a servo(think RC) when added to the correct controller .
I saw an exhaust valve opereted by a RC Servo on a Yamaha RX engine with a cylinder swap, by two wire, but is possible to use an RC servo directly with speeduino?

maybe it is OT but can be useful also for the author
You should be able to use PWM using the VVT table as suggested above. The servo would probably need to mounted away from the exhaust heat.
#52105
JHolland wrote: You should be able to use PWM using the VVT table as suggested above. The servo would probably need to mounted away from the exhaust heat.
Sure! Speeduino's VVT pin out is at 5V or 12V?

EDIT: It should be 5V
#52112
The motor unit I have from the exup valve IS a servo ,just like the RC ones, a motor and a feedback potentiometer. You just need the appropriate drive circuit which is easily achieved with a nano etc.

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