2 Strokes Down Under

I have just acquired an MC21 that has no spark on the uppermost cylinder. I have checked wiring and swapped coils and swapped pulse generators (the sensors at the flywheel) and both work on the front (lower) cylinder. I'm a bit confused that the lower pulse generator (front cylinder) air gap is .012" whereas the upper one that doesn't work is .025" I would have assumed both would be the same gap.
I haven't tried to start the bike yet as I'm going over it as it's been standing in the weather for a few years and a lot of the electrics weren't working.
I am a retired mechanc and done a fair amount of electrical work on late model cars so understand computers and working through wiring etc.
Any advice greatfully appreciated.

you checked and cleaned all connectors? Set the air gaps the same. I'm guessing you have also gapped your plugs correctly and new plugs?

Fresh battery? the cabling itself is in good condition?

Where abouts are you located?

Thanks for your reply. I've installed a new battery and been through all electrical connections from the pulse generators to the coils, ignition and run/off switch and all connections at the ECU (computer). As I mentioned, the bike was left in the weather (without fairing) for a few years and as some switches did not work I went through the whole electrical system, every connector block!
I've fitted new plugs.
As far as the air gaps are concerned, the bottom sensor/flywheel gap is .012, the upper one (that is the non-firing pot) is .025, almost double! There is no adjustment, that is fixed. Both pulse generators look identical and when swapped the one from the non-firing pot will spark so I know both work. Also both coils & plugs work when swapped.
Unless one pulse generator is longer than the other in order to obtain .012 gap then I'm assuming it's designed this way!!!! As to why is beyond me!
If that is the case then the only possibility is the ECU (computer).
I live in Nairne in the Adelaide hills.
Thanks.

It's been a while since I have tinkered with the air gaps and I won't be able to check what mine are set to for a while. I would try and make a little bracket or file out the bolt hole so you can get some adjustability.

ECU = PGM for the NSR, Honda's special herbs and spices to make the engine work well.

If you've swapped everything and it still works it's most likely the Ecu

If you can get anyone to repair it just get a zeeltronic etc

Step1
Throw PGM in bin
Step 2
Buy Ignitech and wire in set to 'NSR 250 MC18'
Step 3
Ride away.

Thanks for the replies and advice, much appreciated. Regarding filing out the holes in the non firing pulse gen, I'm wondering if the Honda setup is similar to some of the Mitsubishi Lancers where the ECU relies on the first fire-up to energize the other pots. Should this be the case I'd be a bit concerned altering the air gap.
Regarding the Zeeltronic (?) & Ignitech, where do I buy such a beast and wiring guide? There is a place in Adelaide that has S/H parts for an MC18, would that be a place to start?
I'm about to test the circuit by adding a .010" shim to the non firing gen magnetic pole and see if it produces a spark on crank. That would effectively prove the circuit & ECU (or PGM as you describe it). If it doesn't generate a spark I could consider the PGM at fault.
Will advise the result. Look for the smoke!!

Join the NSR forum you might get better info there. Be warned though they are mostly tossers
http://www.nsr250.net/forums/viewforum.php?f=2

EPApolice wrote:Join the NSR forum you might get better info there. Be warned though they are mostly tossers
http://www.nsr250.net/forums/viewforum.php?f=2

Hey Pat need your bank details

The MC18 map on the ignitech was found to be slightly flawed, I can't remember what the problem was, but a guy in South Africa said it wasn't working properly.

Hopefully you generate smoke of the non electronic kind.

Good day mate !

About the ignitech unit , I have one on my nsr , between my friend and I we could not get it to run . I eventually ground off the extra lobes on the flywheel and ran it with 1 lobe .
It seems to work ok and is getting better as we fine tune it . My mate tried to fit one on his mc21 . The wiring diagram that he got from ignitech had a mistake on it . He eventually got it working but later took it off his bike as its main use was on another bike .

During this time I was seeking help from everyone , Matt from Tyga installed one on a nsr and had the same problems . As he is friendly with ignitech they were going to sort it out between themselves . It should be ironed out by now .

Could you check if that pick up is sending voltage when kicked over ?

cheers , Neal from Sunny Perth

Wonder who the genius is that recommended the single lobe

A good man !

I sent you a text Lozza but you have a PM now also.

I think I'll forget the ignitech and grinding off a lobe makes no sense at all, if that was what Honda intended they would have deleted it. Anyway, that would isolate that cylinder completely and a one lunger is crazy!

There is some voltage from that sensor on crank but I'm thinking the air gap is just too wide to generate a lot I really can't remember how the two voltages compare but will have another go. That's good advice.

I know the sensor is fine, I've swapped it with the "firing" one and it works in that position.

I'll give the NSR forum a go, never know what might transpire.

I haven't tried shimming the sensor yet, I need to get some .010" shim stock.