Ignition Test Bed

[linguist]

Hi All,

I have been playing around with an Ignition system for a motorcycle that I am building in an attempt at a land speed record either this year or maybe next year..

I have attached several pictures & need some help with things--as usual!

First up I built a small test bed as shown, it has the flywheel generator at one end & is driven by a small universal ac brushed motor cooled by a microwave oven fan. I made a motor control circuit to vary the speed etc as shown.
(Yes, I have a cover for the bottom of the red switch so the connections are not bare as shown, thought I'd get in first as someone would have said something .

The drive motor is only 900W & is only capable of driving the generator to around 3500rpm--NO GOOD!
I then found a couple of other universal motors on some leaf blowers at the local tip, on the specification tags they are rated at 2400W.
I tested the current draw on the leaf blowers but they only draw around 4 Amps from the supply making them about 900W or so?
Shouldn't they draw 10 Amps making them 2400W or are they not loaded enough in the leaf blowers to draw this current?
Or are the manufactures misleading people?

If these motors are not suitable & to small which appears to be the case, what other motors can I use that I can control the speed of with my circuit used for the universal motors.
Can I use a 240v Induction Motor, the ones without the centrifigul switch or capacitor start?
Not sure about this or what types of motors I can control with my circuit, it's pretty basic?

The next thing is the CDI Ignition circuit.
My bike has a battery & a cdi ignition with an advance curve that is suitable for granny motoring to the shops & cannot be adjusted.
I need to discard the battery totally for weight reduction & have a CDI that will have some advance with no breaker points & no battery.

The circuit first:
The spark at the spark plug is not a solid single spark but a multitude of very fine sparks, a weak spark.

Could you have a look at the circuit attached & see where I can make some improvements in the output.
I have tried several capacitor values at C4 & C5 but it is best with the two cap values as shown at the moment.

I can only test to 3500rpm at the moment & at 3500 rpm the output from the gen coil-source coil loaded with the circuit, plug, coil etc is around 40v peak.
The bike will rev to about 8500rpm when finished & I am unsure what the gen output will be at that rpm until I can drive the test bed to that.
At lower rpm the spark plug still fires no problem but with several fine sparks instead of a single solid spark.

Maybe I need to rewind the Gen source coil for a higher output but I didn't want to do that until I can see what the output is at peak rpm now.

Thanks

 

[cowboybob]

Just a thought. and I am by no means an expert here on this issue, but have you considered a magneto? No battery required.

BTW, pretty cool you're going for a land speed record. No doubt you've seen "The world's fastest Indian". What an outstanding movie. I've watched it 5 times and still keep seeing something new.

I love how the character, at the beginning of the movie, on waking up, looks at the bike (off screen) the very first thing. My other fav is when he chokes off the carb with his hand.

Where are you doing the speed record attempt?

 

[jpanhalt]

I can see how the battery weight issue comes into play for long distances and efficiency, but for a short speed run, I am less convinced that a high-capacity, high-discharge LiPo or similar battery would have a disadvantage compared to the power drain and weight of a generator system.

Are you aware of the several threads on modeling sites for CDI systems with advance curves for aircraft and boat engines turning in excess of 20K rpm. What rpm will you need? How many cylinders?

John

 

[linguist]

Thanks for the replies,

cowboybob,

Yeah I looked at a Magneto but thought I may be able to modify the existing setup, their are a few options & I am open to suggestion.
I think the movie is a classic as well, he did well for a carpenter by trade.

I am going to attempt a record at Lake Gairdner South Australia, I won't get a world record with my single cylinder but I am shooting for a class record for the bike. World records need multi cylinder engines really. After I run this bike I may look further into it.

jpanhalt,

Yes I see your point about the weight issue, my biggest problem is that the bike is heavy & I am
183cm & 80kg at the moment, i'll be a lot less when I have the run though.
Every ounce or gram of weight reduction is imperative.
In saying that the rotating mass of the flywheel & the load on it along with the stator weight etc etc has a huge influence as well.

This is a single cylinder 500cc the redline will be about 8500 to 9000rpm, I build race engines & am shooting for a lot of Torque high in the rpm range rather than very high rpm to try to keep the old girl in one piece.
No I haven't seen the RC Ignitions but I am certainly interested in having a look.

Yes for short duration runs a lightweight small battery could be used, good thought.

Any help will be appreciated.

Thanks.

 

[jpanhalt]

Here are some of the links I have:
http://www.modelbouw.gompy.net/newcdi/index.htm
http://www.sportdevices.com/ignition/ignition.htm
**broken link removed**
**broken link removed**
http://www.rcuniverse.com/forum/m_4344316/mpage_16/key_/tm.htm

The threads tend to get quite long. The first link is an actual construction site. Gompy (aka BigBoat) uses these ignitions in racing model boats. Those really turn up the rpm. 500 cc is not that much bigger than some model engines. Desert Aviation (DA, no link real handy) in the US may have an off the shelf ignition that will work for you. 9000 rpm is not that high for model engines. I thought you would be doing twice that.

For a 15 minute or less speed run, a small battery pack will be more than sufficient and weigh far less than any 900W generator you may come up with.

On the above sites, a person named Nyemi is mentioned in several places. He is the programmer. The typical approach is to use a CDI with homemade coil (for weight reasons), Hall pickup (a 4-cycle has a waste spark), and a PIC chip using a lookup table for the advance. The 16F628 chip is popular, but the most recent versions use a newer chip and bootloader so you don't actually have to have a PIC programmer, if you have the chip with bootloader already in it. Several of the activists in the projects are from Oz. I think one is named 'bluejets."

John

 

[linguist]

jpanhalt,

Thanks for the links, i'll have a look at them & see.

9000rpm for a 500cc single cylinder engine is enough without exotic components the redline std is 6500rpm, Formula 1 engines only spin to 20k or Nascar to about 9k & there big money engines.
Model engines are small & lightweight so can spin to a lot higher rpm.
My piston would weigh more than a model engine complete.

Giving some thought to this today & seeing that engines are application based as is everything.
There's two ways to look at this, lightweight flywheels etc enhance acelleration, but for this application where I want to wind this thing out for maximum speed not acelleration a heavy flywheel may be of advantage.
My thinking is at this stage that a heavier flywheel when motivated has more inertia & will tend to want to keep the bike going.
Lighter components as used for most racing purposes help the engine acellerate harder.

An engine with a heavy flywheel is slower to acellerate but harder to stop as well.

So I'm back to being undecided I have to say?

More testing to be done yet.
Thanks

 

[jpanhalt]

Don't forget the gyroscopic effects of a heavy flywheel either. The Gnome rotary engines (https://en.wikipedia.org/wiki/Le_Rhône_9J) made the aircraft on which they were used a bit squirrelly to fly.

John

 

[maq67]

Hi All,

I have been playing around with an Ignition system for a motorcycle that I am building in an attempt at a land speed record either this year or maybe next year..

I have attached several pictures & need some help with things--as usual!

First up I built a small test bed as shown, it has the flywheel generator at one end & is driven by a small universal ac brushed motor cooled by a microwave oven fan. I made a motor control circuit to vary the speed etc as shown.
(Yes, I have a cover for the bottom of the red switch so the connections are not bare as shown, thought I'd get in first as someone would have said something .

The drive motor is only 900W & is only capable of driving the generator to around 3500rpm--NO GOOD!
I then found a couple of other universal motors on some leaf blowers at the local tip, on the specification tags they are rated at 2400W.
I tested the current draw on the leaf blowers but they only draw around 4 Amps from the supply making them about 900W or so?
Shouldn't they draw 10 Amps making them 2400W or are they not loaded enough in the leaf blowers to draw this current?
Or are the manufactures misleading people?

If these motors are not suitable & to small which appears to be the case, what other motors can I use that I can control the speed of with my circuit used for the universal motors.
Can I use a 240v Induction Motor, the ones without the centrifigul switch or capacitor start?
Not sure about this or what types of motors I can control with my circuit, it's pretty basic?

The next thing is the CDI Ignition circuit.
My bike has a battery & a cdi ignition with an advance curve that is suitable for granny motoring to the shops & cannot be adjusted.
I need to discard the battery totally for weight reduction & have a CDI that will have some advance with no breaker points & no battery.

The circuit first:
The spark at the spark plug is not a solid single spark but a multitude of very fine sparks, a weak spark.

Could you have a look at the circuit attached & see where I can make some improvements in the output.
I have tried several capacitor values at C4 & C5 but it is best with the two cap values as shown at the moment.

I can only test to 3500rpm at the moment & at 3500 rpm the output from the gen coil-source coil loaded with the circuit, plug, coil etc is around 40v peak.
The bike will rev to about 8500rpm when finished & I am unsure what the gen output will be at that rpm until I can drive the test bed to that.
At lower rpm the spark plug still fires no problem but with several fine sparks instead of a single solid spark.

Maybe I need to rewind the Gen source coil for a higher output but I didn't want to do that until I can see what the output is at peak rpm now.

Thanks

Hi, I need to build a test bed for cdi, can you send me the plane or report the type of engine you are using? sorry I do not speak inglea, tradutor use google.