Building an Adjustable/Tune able CDI

[Rubbersalt]

Does anyone know if an adjustable or Tune-able CDI is available for the blaster?

If not, I think I should create one. I've already done extensive research and began reproduction of the Tecate 3 CDI (first to be produced in 30 years!). I've began creating the schematic for the Tecate to allow for some adjustments and tuning. Then it came to me... My favorite quad doesn't have any CDI adjustments, only a crappy ignition curve!

In the past, we've used the hotshot CDI and adjusted timing 4 degrees, but that can only do so much.

Would anyone be interested in a tune-able/adjustable blaster CDI?

Below is an example of a couple of my prototype CDIs that have a way more aggressive timing curve. They are 2-3 times the size of the OEM blaster CDI. These are my Tecate 3 CDIs. Due to demand on a 32 year old machine, I opted to use a 3d printed housing opposed to a molded one.

Let me know your thoughts, comments, and suggestions below.

 

[79 bronco]

This is interesting!

 

[Jimmer]

Here it is:http://www.hpi.be/item.php?item=068K067

 

[Rubbersalt]

Headlights aren't an option with that. It's the same problem the Tecate set up has. Either buy the rare discontinued CDI, or by a complete PVL set up (just like that hpi) and get rid of the lights. Your also limited to 2 settings with that. I'm looking for at 27-64 combinations. essentially a few adjustments for the entire curve, mid, and high.

I've got a PVL set up for my Tecate. While awesome for reving fast, it doesn't hold the torque for my fatness while riding lol. Those set ups are great for pencil thin drag set ups. They don't have much inertia due to lack of outer rotating mass. Heavy flywheels rock when shifting gears. Much bigger power hit, the engine doesn't bog. It does take a little longer to rev up though.


This will be an OEM plug and play style with options to adjust the timing curve.

 

[Rubbersalt]

I've got the CDI torn apart. Talk bout a cheesy set up. It's got 9 components. The board was speced to have another cap, but doesn't. It's completely missing from the factory.

The film cap is rated for 250 volts. About average I suppose. Not Eve close to the 600 on my tecate setup.

All the resistors are quarter watt and the diodes don't look any better. I'm going to start drawing the schematic out tomorrow and see where I can go from there.

 

[Rubbersalt]

These are the images from the tear down. As you can see, the spot labeled "C3" is missing a component. That || is the symbol for a non polarized capacitor. In this case, it'll be a film cap. Ceramic caps don't hold true to their capacitance at lower voltages.

The black gunk you see on it is the encapsulation resin. It is designed to protect me from digging into this like so.

This is the list of components inside the CDI:
1 - Capacitor - Film - 1uF 250 Volts
1 - Capacitor - Electrolytic - 22uF 25 Volts
1 - Resistor - 2.2k
2 - Resistors - 1k
1 - SCR - 2p4m - rated at 400volts
3 - Diodes - D9
1 - Diode - 1D2NB

 

[Rubbersalt]

I finished up a rough schematic of the CDI. This should suffice.

 

[Jimmer]

I certainly get the no headlight charging coil part. You can program in any curve you want with the HPI and have two different setups at a time if I understand it correctly. I think your idea with a real flywheel and more curves would be useful. So you would be able to have numerous curves and change it with a dial switch ? I noticed we are both in Wichita btw.

 

[Rubbersalt]

Correct, I'd be either a set of Dials or switches and dials. There will be an equivalent to OEM settings marked, but the ability to change the curve all together.

It is still going to be an AC-CDI, like the blaster, and be a direct plug in play with all the OEM components.

AC-CDIs are CDI's based on alternating current. They have a source coil, and may contain a trigger coil(blast does). They cannot advance the timing, only retard it. There is no crank position sensor.

The problem with the current set up of advancing the stator, is that your going to be stuck picking were you want your power to be. You can advance it, and at one RPM range, it will run amazing. The other parts will be missing out on potential power. At the upper end of the RPM range, the timing really needs to be altered in order to take full advantages of the cylinder pressures.

When running other fuels, such as 110, alcohol, or e85, the timing needs to be adjusted more.

With the set up that I'm working on, I'd still recommend advancing the stator to bring the base ignition timing up. From there we can retard the curve to suit the engines better.

Higher comp needs less advance. Drag pipes need less advance. The extra cylinder pressure burns much faster and hotter, less time is required to complete the burn.

Maybe we'll meet up some day and put these to the test. I do have ideas for a programmable set up, but that's for a later date in life.

 

[dirtysquared]

Good stuff man. I'm watching this for sure.

 

[Rubbersalt]

This is a theoretical chart for ignition timing curves. I located some blaster timing curve and through it in there. The 3 others are just ideas. I've also created a theoretical CDI schematic to do some timing adjustments. I've also included a chat found on http://www.dragonfly75.com/moto/timingreqs.html that explains when to advance/retard timing based on scenario.

 

[Rubbersalt]

I've got a CDI built, but would like to test it on a machine with an adjustable stator plate. Is there anyone in the Wichita KS area that would be down for some testing?

This CDI is based heavily off my Tecate CDI design(almost the same set up). I figured tossing the blaster CDI and starting here would be the best bet. It's way more versatile and has a much nice timing curve for hi performance 2 strokes.

 

[timstoys]

Rubbersalt, I haven't seen any response here so I figured I'd make an offer. I'd really like to test this. I'll even pay for shipping. Just let me know what kind of tests you'd like done.

 

[Markblaster]

Interesting stuff. But that photo of the board is not very nicely done. Layout looks like it could be made a lot smaller. Why not design the board up in a electronics software and get some boards made in china cheap. Brother gets boards made there all the time with out any problems.

 

[Rubbersalt]

The lay out can be made smaller. Currently they are designed on the same pcb I did the tecate CDI on. I've revised and remade and revised and remade. I did deliberately leave it larger(It's still small overall). It'll be much easier to tap into for the next part. The tune-ability of these. The picture in the first post is from an early early early build. You clearly can see multiple resistors in parallel to get the required resistances. This was do to lack of exact components.

I can currently mask, etch, cut and drill 4 boards in a couple hours. Creating the masking is by far the slowest part. I'm using a CNC laser. Followed by the etching. Then cleaning the boards. Then drilling. Then populating and soldering. Actual man hours, about 30 minutes per board.

If any of these make it to production, I highly doubt the volume of sales would be enough to augment the cost of paying some one else to make them. If the demand was high enough, I'd pay that cost.

Those boards are ~ 35mm x 50mm. I'm cutting them from 70mm x 100mm boards. Score and snap method. Rectangles are easy.

These are a better. Much less snapping and more scoring.




The cost of paying some one else to make these isn't cheap. For small quantities and prototyping, It's not worth it, and it's time consuming. The cost to have just a plain single layer PCB made is about $80(without components!!). I can get around 250 made for around $400. I did the math, and for $400, I can have the tooling and make 250 of them on my own. I've invested in tooling, components, and time. I do need to get a few more things, such as acquire proper PCB cutter lol. If the demand for them does pick up, or I branch out and reach into even more markets, I'll look into getting a dip station.


For just over $1000, I was quoted to have 25 made. Those were standard tolerance passive components with 200 volt ratings. I refuse to use low volt sloppy parts. Stock caps run in the 10% tolerance range. I look for the tightest tolerance components. Quality is made with consistency. Each of my caps test within 1% of it's rating, and yes, I test everything prior. My set ups will handle, at a minimum, 400 volts. I've got a couple of Tecate setups that will do 800 volts. This raises the roof drastically, as well as longevity.
Everything used has a 200-500% higher power limit over the OEM stuff. This ALLOWS for more power to go into it, netting a much much much much hotter spark. Spark starts at your source coil. In order to reap those rewards, you'll have to have a custom done source coil. For the ultimate heat, you'd need multiple coils strapped together. But these can handle that. Oem will get toasted.



As for testing, Tim, you'll need an adjustable stator plate. Something with a good amount of range. I've got some work to do before I send any out for testing.

 

[timstoys]

Rubbersalt I have an adjustable stator already. If I need more adjustment than I already have I also have a grinder and I'm not afraid to use it. Let me know as soon as you have something ready and we'll get some testing done.

 

[Rubbersalt]

I've made progress on the design. I've also picked up an adjustable stator plate. Now I need to port the top end and reassemble.

 

[best]

Rubbersalt, I am very familiar with altered curves on 2 stroke ignitions.
What you are proposing will really liven up a modified and piped blaster.
The timing retard at top rpm with drive heat into the pipe changing its timing for the better and protecting the engine from detonation. The DT200 timing my son's Blaster has run showed the difference it a wild top end powerband. You have to back the stock Blaster timing off to get the same effect, losing mid-range and bottom end. The "Firefly" website you point to is a guy I regularly chat with on a motorized bike forum. We don't always agree but he is bang on with the 2 stroke timing stuff. Keep it up buddy!

Steve

 

[timstoys]

Great to hear about the progress. I haven't made any in my bike. I did manage to get the new motor in my 74 Corolla (but that's another story). My bike has sat all summer because of the heat issues (well that and I had a DRZ400 and my FZ09 to ride ll summer). I'd really like to make some progress on my little bike tho. I put more money than I should have last winter and the wife is not happy I haven't ridden it. If she knew how much I actuall spent I'd be looking for a new home not adjustable CDI..

 

[timstoys]

Hey guys I had to go get a shovel to dig this post up. Is there anyone still thinking about this? Rubbersalt any news? Best I have a DT200 CDI. Does it need a battery or will it run without? Thanks guys.