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Points Setting


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Hi all,

On my Sherpa 325 I put InMotion electronic ignition - bolt on - could not have been easier. Easy starter no problems.

On my Frontera 152 I couldn't afford the electronic ignition so stayed with the points system. Took a while to set up, the bike had been sitting for years and the stator and accociated bits were dusty, rusty and neglected. I cleaned everything, new points, condenser, replaced the lighting coil, all seemed to go together easily.

Set the points gap and bought myself a dial guage to set the timing.

An evening in the garage had things assembled and timed fine.

Ripping across the fields and around the yard the bike went very well, easy to start, hot or cold. on it's third outing it developed a backfire - from/through the exhaust I think - not the carb. I thought it might be muck in the carb and cleaned the tank and carb and checked the flow from the taps. All clean and lovely.

Next time out backfire was still there.Still easy to start hot or cold. It was a mid range backfire on acceleration, wide open throttle seemed to be fine.

Next time out, won't start. Plug is getting wet and there's a good spark. Air filter is a new oiled Inmotion one.

Anyway, decided to check points and timing again.

Points gap was a bit wide - reset that.

I had marked the timing on the back plate and that hadn't slipped as I thought it might have done.

NOW - the question is: no matter which combination of leads from the stator I connect to my timing test light (as well written up elsewhere on here - and in the workshop manual) I can't make it go on/off with the opening of the points - only if I take the stator off the crankcase can I get a make/break circuit.

Where am I going wrong? Surely one side of the points should be isolated from earth... I think.Or not. I'm not sure now.

I've not dismantled the points from when it was running great.

Am I missing a tiny fibre washer that I remember from Mini and Cortina days?

Everything else works fine - stoplight, headlight, tailight, horn (haha) - it has a two week old MoT.

Where am I going wrong?


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Normally speaking the green wire is ground and must be disconnected; (when timing).

black wire is hot to coil, the points don't usually have any loose washers.

If you cant get things to work with breaker plate mounted; it is grounded somewhere

it shouldn't be.

Disconnect the kill button to eliminate any silliness with it.

As far as the bike not starting & has good external spark;

1. new sparkplug (best, ngkBPR5EIX-11) or colder for alpina application.

2.Automotive condenser under tank, mounted on coil bracket (clean for ground).

3.H.T. coil(under tank)

I have tried to cover your problem in the least labor intensive manner.

You can certainly try the Sherpa coil.

Good Luck & be sure to keep us informed as there is a lot of knowledge here.


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First of all make sure the points are clean, the smallest amount of grease or oil will stop them working. The best way to ensure they are clean is to pull a clean piece of paper though them after you have let them close up on the paper. A while ago I had a similar problem and it turned out to be the tapped hole on the points where the wires attach was not fully tapped through. So when I tightened it up it bottomed in the hole leaving the wires ever so slightly loose causing no end of problems.

Cheers Greg

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I agree with all suggestions above. I would however not use a BPR type plug. Only

Use a BP type. The R stands for resistor and it is used to suppress radio interference. They can and should be used with modern bikes but the increased resistance while being used on the bultaco can sometimes cause ignition issues.


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Hi,an interesting carry on,but I have 2 things for you to have a look at. Your picture shows the crankcase behind the points plate in a bit of a state. If it was mine I would remove the points plate & give the casing a good scrub with Fairy power spray, and a stiff toothbrush. It is a cleaner for ovens,& pans etc:but do wear gloves,it is rather nasty stuff for skin ! It may take a couple of goes,then clean thoroughly with hot water. Why do I tell you this? Because I think you have high resistance between 2 aluminium surfaces. Next,strip back an inch or so off one of the wires terminating up under the tank. If blackened or discoloured at all,replace all 3 or 4,whatever you have,with new tinned wires.I say tinned,much better quality than bare copper. I accept it is fiddly & time consuming at the points end,but do it as quality electrical contacts is the only way to go for reliability. Finally,put the condenser up under the tank as often mentioned in these forums,it is well worth doing.Hope this helps,John.

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While we are trying to get the old girl going, is it maybe flooded?

Put the mag cover back on & with a good dry plug of your choice, holding throttle wide open

& give it a kicking go & see if it will a least pop.

Still, better add the condenser, we haven't touched on this possible flooding problem. (my friends suggestion)

Only a suggestion to dilemma.


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Sadlotus -
Your original post asks "Where am I going wrong?" - well, taking each point in turn, here's a few thoughts of mine :-

1/ "the bike had been sitting for years and the stator and accociated bits were dusty, rusty and neglected. I cleaned everything, new points, condenser, replaced the lighting coil, all seemed to go together easily."
Referring to the photo......+1 johnsy's post re the cleaning. Has someone been using the joint face to lever against? Do you have a paper joint to keep the crud out ? Why did you replace the lighting coil ?

2/ "Set the points gap and bought myself a dial guage to set the timing." .......How did you set the timing when fitting EI on the Sherpa ?

3/ "Anyway, decided to check points and timing again.
Points gap was a bit wide - reset that." .......How come ? What happened the first time ?
In the pic. I don't see any evidence of lube on the moving contact heel, in which case the heel will wear rapidly and REDUCE the gap, not widen it. The felt pad that should lube the cam and control any excess looks rather black, by the way.

4/ "I had marked the timing on the back plate and that hadn't slipped as I thought it might have done" .......If 'slipped' means you expected the stator plate had moved, that's not very likely with three screws securing it...and marking the timing on the backplate is meaningless anyway, as you've altered the timing since - by resetting the points gap...

5/ "timing test light .........workshop manual)........ I can't make it go on/off with the opening of the points" .....Nope , when setting timing I've never been able to myself, or detect any dimming/brightening either, as the test light circuit completes itself by finding another earth. The answer for me is to use a timing/continuity buzzer, which detects the change in resistance when the points open - this allows you to concentrate on looking at the DTI only - far easier than trying to watch both DTI needle and bulb at the same time. Which workshop manual ?

6/ "Everything else works fine - stoplight, headlight, tailight, horn (haha)" ......Assuming you have AC electrics (i.e. direct) how have you wired the stoplight ? Is the stoplamp operated by one or both brakes ?

The backfire/banging in the exhaust sounds like an intermittent ignition breakdown is causing unburnt fuel to collect in the system, which is then ignited when normal firing returns. There are many and varied possible causes....

Hope this helps -

Edited by lorenzo
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Hi all

really pleased with the response to my question. Thank you for all you replies.

Here's an update - more to follow tomorrow - not actually started it yet because it's quarter to midnight and a Frontera - even with it's bazooka exhaust - is a loud old thing. Don't want to give children (or the dogs) next door a fright!

From the beginning I've been following instructions from the InMotion Bultaco workshop manual and a printed out post from on here:


I found myself going back and forth between the two so (unwisely) used the printout - No. I don't know why I followed that primarily. I do (now) know that I should have read the post properly and to the end!


After a bit of logic circuitry in my head I found that if the green and black wires were disconnected at the junction under the tank I can attach my battery, light and crocodile clips between the green wire and earth and make the light go on and off as the points open.



After setting the points I can turn the magneto CLOCKWISE to set the timing BTDC (as the workshop manual says) and find the points opening moment. NOT COUNTERCLOCKWISE AS THE ARTICLE ABOVE SAYS!

This is proven by pushing on the kickstarter (easier to rotate the crank than by hand) which will rotate anticlockwise. ie the way the engine runs. So BTDC is clockwise.

After that epiphany, it was all plain sailing.

To answer questions above:

Larry, thanks, green wire was the clue. Condenser stays where it is at the mo to avoid another possible fault (mine).

Greychapel and Feetupfun, I did notice that the light dimmed but didn't realise the significance then - also don't have a strobe where I am at the moment.

Larry, Steve and Zerorev3rev4, the plug is new NGK B8ES (non resistor type)

JLpar, checked thru the magneto holes to check for touching - all good.

Sherpa325, checked cleanliness and tighness - all good.


1. I have a paper gasket. the exterior joint looks good and the allen bolts all do up snug. Lighting coil was replaced because it was unwinding and someone had made a temporary repair with tape.

2. The InMotion Electronic ignition on my 92 just bolts up - there is no adjustment! Three bolts - done.

3. Don't know why points were wide, wasn't much, I assumed I'd done them 'slack' the first time , What should I lube the little felt pad with? I've been using plain old engine oil. The heel doesn't look any more worn than the others in my box of points (admittedly, we're talking thou here).

4. Good point about the three screws and the stator plate. Not sure I understand how the timing changes when I reset the points, only if I open or close them up or down a bit. Explain please.

5. Yes, I need to get a buzzer. Inmotion Bultaco workshop manual. I also have a Haynes and the WWW (but..."Don’t believe everything you read on the Internet just because there’s a picture with a quote next to it.” – Abraham Lincoln)

6. Stoplight is direct - only on rear brake as per original wiring diagram.

7. The backfiring was happening before it wouldn't start, I'm hoping that by resetting the ignition I can at least eliminate that as a cause. What is strange is that it ran really well for a while then gradually deteriated to a no start. As for an intermittent ignition breakdown, how can I test that?, it ticks over fine and revs high fine, it's the loading on acceleration where it backfires, as tho there's no spark or no fuel. mmm... Ok.... maybe the ignition under load might be breaking down. i have a spare stator to test that - my money's on a carb setting..... I'll let you know.

Setting the points and timing these last couple of days has meant taking the magneto off and on lots of times. It has occured to me that the woodruff key is quite shallow in it's 'trench'. The magneto would only have to slip the tiniest bit to stop the bike and give the backfiring and stop scenario. Next time (hopefully not) I'll check the key before I take off the mag.

Thanks for all your help and enquiring questions.

Update v soon.


Edited by sadlotus
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