DC CDI "transplant" By 7ken (Read 4,712 times)

[tvnacman]

May 10, 2014 0:10:48 GMT -6 alleyoop said:

They advance but only about 1-2 degrees, not much at all and they jump around a little. If you have a timing light put it on and you will see. They do have advaning CDIs that are FIXED advanced and also like the one I have on it advances starting around 3K but is retarded for start ups so it it easy on your starter clutch.
Alleyoop

tvnacman.blogspot.com/

sometimes a video is better , this video is the cdi that Alley is talking about .





John

[alleyoop]

Thank you John,
Alleyoop

[7ken]

From Ken's Unwanted library of Suzuki GS 150

Newer engines with electronic ignitions usually have an electronic advance. Some engines have fixed timing with no advance at all. The lower the compression ratio of the engine means more spark advance is needed. This is because rapid combustion is aided by a high compression pressure. Because the combustion process takes place quicker with a high compression ratio less time is needed, therefore less spark advance. Conversely lower compression pressure slows the combustion process, necessitating more spark advance.


When I (gave up) or tried to order the original CDI I found it nowhere, at least not under it's original part #
Langfang Kokusan D150-LK3.. nothing! 3 attempts @ trying to contact the company, all unanswered.

So I continue, reluctantly.
I've looked at several Chinese sites and forums considering the engine was made there.
(Jinan Qingqi Suzuki)
I even tried to join a couple forums in China but registration was "closed".
One site was helpful in giving me an idea of the advance degrees. Idle 12 to 32 degrees full advance.

The timing from the pulse coil and flywheel seem to be my stumbling place unless I'm over thinking it??
because I don't want to buy another CDI that doesn't work. Maybe a "performance" CDI with a similar map?


Pulse pickup coil has two triggers, one for TDC starting and the other for the advanced spark. The short negative pulse is for the Advance spark and comes first, followed by the stronger negative pulse. As the RPM increases, the pulses grow. When the short pulse is strong enough, it takes over triggering the ignition.
Another

Thanks for any help!

Ken

[tvnacman]

tvnacman.blogspot.com/

I'm not really understanding your goal . What is your plan/goal ?

John

[alleyoop]

I believe he wants a CDI that advances more? He could also slot the mounting holes on the PICK UP COIL and move it to the LEFT, that would give it about a 3% advance.
Alleyoop

[JR]

May 9, 2014 14:51:44 GMT -6 7ken said:

May 9, 2014 14:15:39 GMT -6 JR said:

It would be simple to fix the start system through the brake and if you're willing to do some re-wiring we can convert it to a standard 5-wire CDIU system but you would need to change the coil as well.

JR

It was originally wired with that circuit and I just taped it off so I believe putting it back in will be fairly simple now that I understand it. (read another of your posts) thanks..
Better if I can wire it through the neutral wire/light but that's not a priority right now.

Understanding the the pulse coil wiring, knowing how to connect it using only one wire to the CDI if possible would be a big help. I'm pretty sure even though it's running I have it wired wrong since there is no advance.

Curious why I would need to change the coil?
& would there be other advantages to doing it "that" way?

Ken

First bike I've ever had where I couldn't find a manual or wiring schematic.

Sorry I haven't come back, got a lot of irons in the fire. Now that you mentioned you have a two wire pulse coil and from the article you mentioned on the advanced spark the Chinese CDI you are trying to use is a no go, here is the diagram of the typical DC type setup for that CDI and advanced spark in the sense you mentioned on your cycle is not there.

But most two wire pulse coils are simply a voltage output from one wire and the other is grounded via the second wire instead of the end of the pulse coil grounding to the frame. All coils have a end and beginning with one end being grounded.

The timing from the pulse coil and flywheel seem to be my stumbling place unless I'm over thinking it??
because I don't want to buy another CDI that doesn't work. Maybe a "performance" CDI with a similar map?

 

This is probably the case? In your picture you show a two wire pulse coil and the theory of one part being for starting and idling and the other taking over after start up in this case would only work if the pulse coil has two independent coils? You said earlier that you had 0.7 on the pulse coil, was this measured from one wire to ground or measured from one wire to the other? To have an advanced spark with a two wire pulse coil again each wire must go through a independent coil and ground out separately. The distance between each coil would be the advance and retard of the system.

I'm not saying this isn't possible but I've never seen it on any engine, period. Old advance spark systems even in old V-8 engines had a vacuum advance of the engine and moved the points in the distributer by engine RPM.

There are a few scooters out there with advanced timing but this is accomplished through the CDI alone by reading the RPM of the engine via the coil which also can send the signal to a tach. Same system the CDI gets a RPM reading from the signal of how many times the engine is firing and not from the pulse coil. The pulse coil has only one function, to tell the CDI when to fire. I don't see how the CDI could tell the engine to switch locations on the pulse coil from low RPM to a higher RPM, it should be the other way around the CDI gets a message from a RPM source and we know a pulse coil cannot send such a message?

The Chinese diagram in the image has two ground ports, you mentioned how to wire the two wire pulse coil on your scooter? How do you have the two wires hooked up to the transplanted CDI? One has got to send the signal and if it is indeed a two wire system with one end going to ground then hook one of the wires to the signal pin and the other to ground.

JR

[7ken]

Thanks for getting back JR..

It was when I saw a diagram (pic under CDI pics) showing the 2nd pulse coil wire going into the CDI that I thought to buy and try a cheap CDI.

Yesterday not caring if I fried the new CDI or not I tried switching some wires around.
Gnd 2nd pulse coil wire = no fire
Gnd 2nd CDI gnd = no fire
Gnd both CDI and pulse coil = no fire
Reconnect 2nd pulse coil to CDI = v room but only to high idle.. no advance.

As mentioned in my original post the 2nd pulse coil wire goes to both the CDI and ignition switch and it grounded in the off position. ?? 2 ways of turning the CDI off, cut the 12v and gnd it?

I think the CDI I got (black box no #'s) is designed for an engine with centrifugal or other advance?
Doubtfully possible

[7ken]

May 11, 2014 13:15:27 GMT -6 alleyoop said:

I believe he wants a CDI that advances more? He could also slot the mounting holes on the PICK UP COIL and move it to the LEFT, that would give it about a 3% advance.
Alleyoop

From what limited info I can translate on the 150cc 4 stroke engine from a Chinese forum, This Chinese engine should start at about 12 degrees. At about 2k rpm starts the advance curve or "square" depending on many factors but regardless it ends up at about 32 degrees by 5k rpm.

That's a minimum of 20 degrees advance.

Understanding why engines advance is another forum.

This one has to or it will simple not operate between 1 and 8k rpm..

[JR]

As mentioned in my original post the 2nd pulse coil wire goes to both the CDI and ignition switch and it grounded in the off position. ?? 2 ways of turning the CDI off, cut the 12v and gnd it?

Yes very common, in fact rare to have a DC type CDI with the only way of killing the engine being cutting off the power source.

Even on my Chinese 250B it has a kill switch ground wire to the CDI. When killing the engine you are cutting off 12Vdc and grounding out the CDI at the same time. Does this cycle have a handlebar kill switch? if so then I'm betting the wire splices in to the same ground wire from the key switch.

JR

[7ken]

May 12, 2014 5:23:38 GMT -6 JR said:

As mentioned in my original post the 2nd pulse coil wire goes to both the CDI and ignition switch and it grounded in the off position. ?? 2 ways of turning the CDI off, cut the 12v and gnd it?

Yes very common, in fact rare to have a DC type CDI with the only way of killing the engine being cutting off the power source.

Even on my Chinese 250B it has a kill switch ground wire to the CDI. When killing the engine you are cutting off 12Vdc and grounding out the CDI at the same time. Does this cycle have a handlebar kill switch? if so then I'm betting the wire splices in to the same ground wire from the key switch.

JR

I guess I should have said "3 ways" as there is also a "kill" wire going from the ignition switch to the CDI.

No handlebar kill switch, only the ignition switch.

One pulse coil wire goes directly to the CDI.
The other goes to the CDI and there is a splice taking it to the ignition switch off position, grounded.

[7ken]

Went traveling today to 3 different Suzuki dealers and all I learned is they don't stock the CDI. Talking to one of the techs I asked if they changed the timing from the 125 when they took it to 150cc and he said yes but he didn't have a copy of the specs.
Not 100% sure he's correct but I suspect so. Still the engine still has the same stroke so I'm hoping the major changes were just the bore and jets?

I went down the road and found a CDI for a "125" @ 6x's the price of the last one, brought it home plugged it in and now have top end.
It advances (no dyno) about 22 degrees.

One thing that concerns me is upon reconnecting the (start solenoid) wire I still didn't have to apply a brake to start this engine. That's not cool..
I understand on my Yamaha Mio Automatic why only the brake needs to be applied but there needs to be a neutral switch or maybe like on my Harley I can wire something into the clutch, still a neutral switch is maybe I can wire in since there is a neutral light but I haven't even looked into it yet. It should be ground activated so maybe a splice int the gnd to the solenoid. That's another issue I'll look at later.

I've got the front forks apart so I can't go riding now, but soon.

I will continue my studies but at a slower rate depending on how the engine performs.

Thanks to all for your input..

Ken

[JR]

One pulse coil wire goes directly to the CDI.
The other goes to the CDI and there is a splice taking it to the ignition switch off position, grounded.

Very odd cookie indeed, this tells me that one pulse coil wire is ground and the other the feed and when turning off the ignition you are grounding out the CDI and pulse coil feed at the same time, why they did this, who knows?

Also odd it doesn't have the handlebar kill switch because the grounding out the CDI with it is always what the Chinese do, they never except on a very rare occasion cut the power feed to the CDI through the handlebar kill switch?

It is very common for the Chinese to use a generic harness on several models of bikes/scooters and adapt wires in the harness to do different things on different machines and it seems this is what has happened here.

Also now we know the engine advance is solely in the CDI as I suspected all along. I'm sure a adjustable CDI could be made to work the question would be can one find one with the bottom to top end curve to make the engine run as it should?

JR

[tvnacman]

tvnacman.blogspot.com/

Its rude to ask what you spent on the cdi , it might make me a dead cat . I would like to know .

John

[alleyoop]

Also squeezing the brake to start is a safety feature. You never know if the throttle is stuck open and would create quite an exciting lurch forward when first started without the brake on
Alleyoop

[ullibremen]

Hello I googled I'm curious
It's not that important
but does anyone know
what this cable is for and what purpose it serves

when you cut it
what a sense there in behind .
Where in this schematic is the location of this loop
Image search Google D50-LK26A Peugeot V-CliC
I googled that it removes the speed limit but I'm not at all sure what that means and what kind of speed would be in such a scooter