Modify Velleman Kit - Transistor Assisited Ignition, kit no. K2543

[dr pepper]

Sign216 has been discussing a similar topic only a few weeks ago on this forum, heres the thread:
https://www.electro-tech-online.com/threads/ignition-coil-and-idle-speed.153960/page-2#post-1328216

 

[sign216]

I built the Velleman transistor assisted ignition, and after sorting out a grounding problem, it's been great! Oddly, it solved a problem mentioned in the other thread, but not addressed here:

The bike's idle speed was on the high side, 1,400 to 1,800 rpm. A knowledgeable rider reported that switching from the orig. 6v generator system to a fully electronic 12v system by Powerdynamo enabled him to lower the idle speed. It has battery + coil ignition, so the generator shouldn't matter, but somehow it does.

When I fitted the trans ignition to my bike (and kept the orig. 6v generator and tiny 6 or 8amp battery) I was able to lower the idle speed to 1,250 rpm.
How, why, I don't know.

 

[Crosserke]

I used the K2543 for some mx 500BSA 4stroke engines. It gave "very" good results and was super reliable.
The electrical circuit was adjusted with an inductive sensor (proximity switch) and a fixed 12V NiMH 2400mAh battery.
For the HS coil was used a high energy "Blue Bosch Ignition Coil". The resistance is 3Ω.
https://photos.app.goo.gl/8Rjn2q98pJ2kZ7Ub6

With this, it was easy to drive for 2 hours non-stop.
Problem with the K2543 was to bring the engine to compression via the kickstart.
The ignition produces always a spark when the crankshaft rotates, also when the engine is being compressed.
The HS coil should not ignite when slowly rotating the crankshaft (only when pedaling to start).
A rotation check could solve this problem.
Someone suggestions?

 

[sign216]

I don't understand the problem. The ignition system produces a spark whenever the crankshaft turns into position and the system is "on."
If you don't want a spark at low speeds when the engine isn't "on", turn off the ignition switch.
Perhaps I am not understanding.

 

[Crosserke]

These motors don't have an ignition switch but there is the possibility to press the kill switch. You don't want to experience the fact that it ignites when the button is released.
With most battery ignition systems (Interspan, ...), they are made that no spark can occur when compressing.
It must prevent a big kickback (4-stroke).

Interspan battery ignition

 

[Western]

I had a feeling you were wanting to avoid a kick-back. ☺

What model/year 500 are we talking about here?

 

[Crosserke]

BSA B44 (motocross)

 

[sign216]

I feel that at it's heart, this is not a electronics question, but a question of kick technique.

Other motorcycles produce a spark no matter the rotational speed of the crankshaft (unless they are a magneto instead of coil+battery).

 

[Western]

BSA B44 (motocross

Cool ... I have a B44 ... though mine was an onroad version.

I also have a spare B44 motor ... which I am led to believe was from a motocross bike. Has the round finned barrel, whereas the other is square finned.

 

[Western]

Problem with the K2543 was to bring the engine to compression via the kickstart.
The ignition produces always a spark when the crankshaft rotates, also when the engine is being compressed.
The HS coil should not ignite when slowly rotating the crankshaft (only when pedaling to start).

feel that at it's heart, this is not a electronics question, but a question of kick technique.

I suppose to a degree you are right ... but if you know these long stroke motors ... you know that the starting technique is to push the motor over gently until you reach compression ... then using the decompression lever ... push a little bit further until the piston is just over top dead centre ... then give it a good kick.

If things don't go well ... you can get a pretty decent kickback if it doesn't start ... but that is a chance you take with an old motorcycle like this.

But if you have a really good ignition system ... that fires every time the points open (even at 0 rpm) ... when you are gently positioning the piston for your starting kick ... you can possibly get a nasty kickback before you even actually try to start the thing.

I'm betting that is what Crosserke is trying to combat.

 

[Crosserke]

I'm betting that is what Crosserke is trying to combat.

Completely correct!

 

[Crosserke]

I post an electronic diagram where the ignition coil is switched off at low rotation.
There is no ignition during crompressing.
Even if the engine is not running, the HS coil is switched off so that it can not overheat and prevent the battery from discharging.

 

[Crosserke]

 

[shortbus=]

I don't understand the problem. The ignition system produces a spark whenever the crankshaft turns into position and the system is "on."
If you don't want a spark at low speeds when the engine isn't "on", turn off the ignition switch.
Perhaps I am not understanding.

Guessing you never owned a kick start Harley?

 

[sign216]

Guessing you never owned a kick start Harley?

Right now I have four motorcycles, three of them are kickstart; Benelli (Italian), Gilera (Italian), and BMW (German). I've had the BMW the longest time; 25 yrs. Never had kickback.

Never.

It might be the design. BMW has a good reputation for design. I've heard that kickback is an issue for many cycles. I wonder what elements of the design lead to that? It could be that all my bikes are between 106 and 500cc, which might limit kickback. Open to ideas.

Joe

 

[shortbus=]

How many of them have an electronic ignition? How many have a retardable ignition? With a standard points ignition the plugs don't fire when bringing the cylinder up on compression slowly, but an electronic one will. If you forget to retard the ignition on a Harley when starting, they will usually remind you that you should do it. And with the Harley you need to bring one cylinder up on compression before putting your weight into the kick. I have two Panheads, a '57 and a '58, and also have what is known as "Harley leg", where my right leg is more muscular than my left, from the kicker.

 

[sign216]

BMWs, the older ones, are twin cylinder kick start, but aren't known the kickback problem. But these are smaller engine, between 500 and 600cc.
That could be the reason, or maybe there's something in the design. I don't know.

I've heard of the problem w many other makes.
Seems like before they solved it, electric start came a long, and designers forgot about the kickstart problem.