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Being aware that the optimum resistance for the coil is 300 ohms I was wondering just how low readings can go before significant starting and running issues are experienced.

No doubt there is much information encapsulated within these pages but I note the Dutch site indicates circa 160 ohm is a base line.

Any comments from those with actual knowledge of this?

As a matter of interest,electrex allegedly have one electronic ignition system for the 350. I ordered it but they sent one for a single! I say allegedly because staff seem unaware of its presence however one was sure that there was such a system in stock.

They were quick to send the part out and collect but due to a misunderstanding where I expected the correct part to follow the incorrect item my patience wore thin hence no ignition. £240 including coils if you are interested? 3/5 amp drain.

I am now wary of Internet purchases like this as when they go wrong I seem to be out of pocket for postage or simply waiting for refunds..nothing I have bought from suppliers has been as expected this year!

buell1203 wrote:Being aware that the optimum resistance for the coil is 300 ohms

As I have written many, many times, the 300 ohm value is just nonsense.

I've measured the diameter of wire that the ignition coils were originally wound with and there is simply not enough room on the bobbin for enough turns to reach 300 ohms.

A number of good original coils measured by myself and others have been close to 220 ohm as have ones I've wound with original diameter wire.

300 ohms coils have been wound with thinner wire and may give more margin if you have a weak rotor.

I suppose it's possible that early coils were wound with thinner wire and gave rise to the 300 ohm value in the 'blue book' but were even more prone to breakdown than later coils which is why they changed.

My all original ignition system (with remagnetised rotor) lets me pull to 10,000rpm at Cadwell.

I do not doubt you Paul but was trying to verify my own thoughts on the matter before rewinding.
My coil shows 140 ohm on one meter and 205 on another. Obviously one is useless but the two readings give a baseline.
I have sparks on both plugs,weak but good enough. Plugs are new as is the file but it will not go.
I cannot bump start it due to health reasons nor do I have access to a roller.
It should start but doesn't!

I could rewind it and find the same applies..then again I could be lucky. What do you think?

Well, 140 would be very low indicating a number of shorted turn, 205 is Ok-ish. Have you got a fixed resistor you can check your meters against?

I'll repeat the old saw about most ignition faults being caused by carburation and vice versa!

There is a definite starting technique. Bring it up to compression and kick it over compression and kick it fast. I find it helps to have the throttle just cracked open.

There is a long firing interval and a short one. It's easier to start on the short one because one swing will get you over both and you can use the momentum from getting over the first compression to help you get over the second faster.

Where are you based, you haven't put anything in your profile?

Yes I am aware there is a knack to starting them. The last one I had would only start on the rear choke and a whiff of throttle. Rpm immediately went to circa 4k then I had to gently coax it to keep running. This does not even give a hint that it will start.

I am used to starting recalcitrant bikes as I have examples ranging from 1924 to the present. One learns a few tricks over the years but there is always more to learn! Even easy start is not working( and I have tried with the carbs off to isolate them as the fault)

The carbs were rebuilt with new gaskets etc but admittedly they are leaking and need remedial work,

The plugs get wet so fuel is getting through.

Ignition timing and valve timing are ok.

No I do not have anything to check the meters against but I have now binned the one giving a low reading.

Well at least it saves me the trouble of a rewind. I have the cable but was wary of stripping the coil as I could not believe this was the answer. This was why I thought of going for a digital ignition update. I am still considering the sachse system ,expensive but at a later point I could buy the updated 300 watt alternator too.no one else does this conversion.

Stuart at nlm sees it as pointless but then with respect he has a vested interest in his own system. I hear it is excellent but it is nonetheless just an upgrade on a 35 year old setup,expensive and not as precise as digital systems. Sadly I would lose the self generating benefits of the original. Anyway,my priority is to get this thing running then decide where next to make improvement.

I am in Wales. No owners around here. I will be at Stafford on Saturday.

The stator winding on mine was giving 170 ohms. It would start, but only if kicked over very quickly. I hate a bike that doesn't start easily so I had a rewind and the rotor re-magnetised which cured it. Then one original transducer died at Cadwell a couple of years ago so I went for the NLM coils/box setup.

Still running an OEM red pickup. I lent the pickup to Jem to get home from Cadwell this year. I was going to fit a NLM pickup but in the end I robbed another red one off the spare 350 motor I have. I had to resolder the trigger wires on to that and so thought it might not be up to much. In fact, it starts and idles so well with that one that it will stay on and the other one (now returned - thanks Jem) will become a spare. Now it may be that by luck I have got the timing just perfect (I admit to not strobing it yet) but there is nothing like a tip top condition ignition system for aiding easy starting in my experience. I even use 'snake oil' Iridium plugs because over years of running Morinis, Gileras and lately old two stroke MX bikes I think they really do make a difference.

That is good to hear. Hopefully I am in the ballpark for a working coil. The rotor is weak in one area when applying the spanner test but I have used villiers systems with weaker magnets so it should work.

My trigger unit (red)also needed a wire soldering. Right at the pot but it seems to send a signal.

The transducers are rather odd, one is red and one grey. They do not correspond with the Dutch website list but do spark. I have vainly assumed they were working before I bought it.

Hendre gave me some advice re the potentially mismatched transducers but like me assumes they worked before it came to my care. The wiring was a mess with separate switches everywhere

It has been frustrating. One advantage of having too many bikes is that one can leave it for months then go back to work on it. When the only bike one tends to burn a lot of energy resolving problems. I am unsure which is the better option.

The transducers do sound odd. I had fun and games years ago on a trip to France on an 87 350 K2. I had actually taken a spare transducer and pickup with me. I must have been psychic as it went on to one pot. In the car park of a hotel I discovered that you can mix early and late transducers and pickups if you get the combination exactly right. You will get incorrect timing on at least one cylinder but it runs well enough on two cylinders as a "get you home" dodge. It's been so long ago that I can't remember for sure but I *think* I must have got it going using a red pickup, one early black transducer (as logic dictates they must have been what I borrowed off the Morini I still have) and one later grey type. If I remember correctly I got a new grey transducer when I got home and put the black pickup back on.

Part of the attraction for me of the new NLM system is the use of standard off the shelf HT coils but I assume so does the electrex setup.

Yes it is likely that my transducers are I correct but I am hoping against hope as if the case it leaves me undecided what route to take.
72degrees suggests compatibility between nlm and standard systems. Totally true.
The electrex system is however more modern. Dispensing with the standard system and being reliant on battery and standard primary coils. This is not compatible with any part of the original system.
It's attraction is that it is a complete setup. Volker sachse who perhaps makes the best system charges 320 Euro but coils are required which increase the costs.
There is another German system from the old mz company. This uses self generating power as per standard but has the advantage of a 150 watt alternator. It costs 450 euro.

Nlm want circa 300 for transducers and trigger. Realistically there is little to chose cost wise hence if I can make mine work with minimal expense I will be very happy.

My transducers are marked
Red 323933. 88. 02
Grey 323987 m87 01

Hendre thinks one is a tritsche replacement but we are not sure

Any ideas? They do not match the Dutch comparison guide.

I'll try and remember to take my bag of spare pickups to Stafford. I had a bunch of them tested on the NLM test rig when I was up there so I know they have basic functionality. They might not perform well at high rpm or when hot (the test rig can't put them under that kind of stress) but they should be fine. I've probably got a matched pair of transducers too.

The red pickup (of which there are two versions which must be used with their correct rotor) has built in diodes. The black pickup doesn't so there needs to be one in the transducer, or you could put one inline.

There MUST be a diode in the system, but it will work with an extra one. The extra diode alters the ignition timing (retarding it) but you can move the pickup to compensate. It may however make it harder to start too, which may be your problem. The number on one of your transducers matches an aftermarket type that should be used with a black pickup (diode in transducer).

Of course, a real gotcha is to have got the pickup leads the wrong way round!

Building your own transducers isn't difficult and NLM's box is just a pair of standard circuits in one housing with external CDI type coils. I made Alex the first one, but they've tweaked one of the resistor values to work better with their pickup. I get my coils from Tony at BTH Magnetos, but any small CDI type should work.

When I got my 350K it was a reluctant starter with around 175 Ohms on the coil.All well after a rewind. Haven't checked the rotor's magnetism yet.

Paul.
Thanks. Will you be on the club stand and if so do you want me to bring my complete system for comparison?

I have looked at the plans for making transducers and considered having a go however I have never built up a circus board and am unfamiliar with the components. I have no doubt that maplins etc would supply my needs if I took the plan with me when purchasing components but have shied away from it. I suppose the key to success I'd good,rapid soldering with minimal heat?

I know I can rewind the coil as I have done so with slot cars as a kid,that is quite simple.

I'll be on the club stand, except when I'm not

By all means bring your ignition bits of that's convenient.

Will do but I will leave the rotor as it is a bit heavier to carry all day.

. . Just wondering, will the Kokusan igntion from a 501 motor fit an early 350?? . .