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Questions on differences between boxes

Posted: 04 Sep 2016, 20:48
by kommando
Looking for some information on the differences between the SECU-3T with MAP and the SECU-3L

I am looking to add programmable ignition curves with mapping to inlet manifold pressures on air cooled twin cylinder and single cylinder 4 stroke motorcycles. The Twins are single spark plugs per cylinder and the singles have dual plugs. All the motorcycles have positive earth wiring and components to suit, changing to negative earth is not difficult but I would like to keep them positive earth as after 30 years of looking after them its imprinted on my brain ;) . Timing signals would be run off the camshafts running at 1/2 engine revs, 1 sensor for the singles and 2 sensors on the twins with a preference for modern coils mounted on the spark plugs for hot spark when kicking over. Carbs are old style and not likely to be ever upgraded to injection. I do not want wasted spark especially on the singles as on these both plugs need full spark when firing but I may go twin spark on one twin but would use 2 dual coils each firing one plug in each cylinder.

Looking through the boxes you offer there look to be 2 solutions that would work but need help to decide which is the better option for me.

1. A SECU-3T with MAP plus 2 BIP373's mounted on a PCB for multi channel coil drivers for neatness. Option to add bluetooth is noted. As the case is plastic and not earthed this should be installable within positive earth and relatively vibration proof. No short circuit or over temp protection.

2. A SECU 3L, this includes MAP and 2 coil drivers internally. Bluetooth does not seem to be an available option, the case is metal and is earthed so the box would need to be isolated from any metal component if it was to be installed into positive earth with the danger vibration could affect this isolation in the future. Does have over current, over voltage and over temperature protection.

Could you confirm my analysis is correct and is there anything else I need to consider. I am currently favouring the SECU-3T with the Bluetooth and plastic case.

Thanks

Re: Questions on differences between boxes

Posted: 05 Sep 2016, 19:44
by STC
Hi,

Your analysis is correct.
Note (for 2 sensors case, sequential), that current version of firmware requires at least 16 teeth on the trigger wheel.

Re: Questions on differences between boxes

Posted: 05 Sep 2016, 19:54
by kommando
Thank you, on the sensors I can make a 16 tooth wheel probably about 50mm in diameter, space is a bit restricted with the chamber on the end of the camshaft 68mm in diameter. Could this handle having 2 hall sensors or is hall sensors restricted to one. If so would a 2 wire CDI pulser be an alternative to the CKPS, the CKPS sensors avaialble look to be too long to fit inside the current timing chamber.

Re: Questions on differences between boxes

Posted: 05 Sep 2016, 22:45
by STC
For full sequential ignition you need 16-1 trigger wheel on crankshaft and 1 teeth wheel on the camshaft.
Possible configurations:
16-1 on crankshaft, 1 on camshaft, full sequential
16-1-16-1 on camshaft, 1 on camshaft, full sequential
2 tooth on camshaft, Hall or VR, but wasted spark only

Re: Questions on differences between boxes

Posted: 06 Sep 2016, 11:40
by kommando
One end of the crankshaft typically has an alternator rotor with 6 magnets, there is a small space out board of this where a disc could be fixed but I assume the 6 magnets could interfere with the CKPS if too close. In board of the alternator is the chain drive to the gearbox, the sprocket for this chain depending on the engine would have 23,26,28 or 29 teeth. Could these be used in place of a disc. As the sprocket is wide you can get the CKPS further away from the alternator rotor and close to a flat face for mounting.

Image

Re: Questions on differences between boxes

Posted: 06 Sep 2016, 13:50
by STC
the sprocket for this chain depending on the engine would have 23,26,28 or 29 teeth. Could these be used in place of a disc.
This will be enough, but some piece of experiment is still take place, I mean quality of signal produced by sensor.

Re: Questions on differences between boxes

Posted: 06 Sep 2016, 15:14
by kommando
I understand, the shape of the tooth may not give a sharp enough difference for the CKPS to give a true on/off signal and get confused, this may need experimentation in angle of the sensor looking at the teeth and possibly different CKPS where the reluctance data is handled differently.

Provided that works then on the camshaft I will need an additional single tooth wheel with a second CKPS with the tooth aligned to cylinder 1 TDC ?

As these are all kickstart bikes if on a twin you slowly bring the cylinder 1 to just past TDC ready for the fast starting kick does the SECU-3 need to see the cylinder 1 TDC signal before firing a plug or does it remember from the last time it was used. There is a Electronic Ignition unit made by Pazon which turns off after 5 secs and then will not turn on until the sensors detect 200rpm ie 2 TDC signals. On certain engines with low kickstart gearing and low weight flywheels you can only start the bike by using starter rollers as the inertia of the kick cannot get the crank around to the firing point.

Re: Questions on differences between boxes

Posted: 07 Sep 2016, 00:56
by STC
Provided that works then on the camshaft I will need an additional single tooth wheel with a second CKPS with the tooth aligned to cylinder 1 TDC ?
70...160 degrees before TDC of the 1-st cylinder compression stroke.
http://secu-3.org/wordpress/wp-content/ ... oscill.png

Yes, SECU-3 needs to see cylinder #1 (pulse from cam sensor). But immediately after ignition turn on, SECU-3 is in Wasted spark mode (two channels will fire simultaneously) and after getting a pulse from a cam sensor it goes into the full sequential mode. Thus, it helps to start engine.
SECU-3 will fire up to 20 min-1 or even more.

Re: Questions on differences between boxes

Posted: 07 Sep 2016, 11:15
by kommando
Thanks, you have this system well sorted, you just have to add in tea making facilities ;)

Re: Questions on differences between boxes

Posted: 07 Sep 2016, 16:55
by STC
Yes, thank you, but a lot of work is still to be done. One of the tasks is to make English documentation better and to extend it.