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I bought an electronic ignition from Newtronic for my 750, and they sent the wrong contents in the package, though it was labeled correctly as I ordered. They were very kind and sent me the replacement "brain" unit immediately, and everything seemed fine...
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Anyway, ever since I installed the replacement "brain" unit that you sent to me, the bike has suffered an occaisional strange "stammering" at low idle. I have done all kinds of troubleshooting, and have always verified that the timing was set correctly according to the service manual.

Today, however, at wit's end, I tried adjusting the timing too far in each direction (advanced/retarded) just to see if it makes a difference.

Here is what I found: When I adjust it so that the timing light shows the line lining up between the "F" and the "T", the problem is worse. However, when I adjust it so that the line lines up at the LEFT side of the "F", the bike runs much better and the stammering is nearly eliminated (of course "normal" is aligned to the line at the RIGHT of the "F"). I suppose if I adjust it even further away from normal, it will run better...

This is very strange - I never had to have it adjusted so strangely with the points! Here is a picture of an example of where I have it currently set:


biquetoast.com/bigpics/78-750-1/20051023...teCurrentSetting.JPG

So I'm wondering - when you sent me a replacement "brain" unit", should I have gotten a different trigger unit as well?

Or has anything like this been reported by anyone else?

Do you have any suggestions?

Thanks for your time...

Post edited by: biquetoast, at: 2006/04/08 08:33

I'm not sure that this is related to the Newtronic ignition, if you advance the timing as you have stated, and the bike runs better, what does Newtronic have to do with it?
On a whim (actually because I had this neat new dial indicator and a degree wheel to play with), I checked the position of the marks on the timing advancer against actual TDC, and found that the TDC mark was actually a few degrees after TDC. Setting the timing accurately resulted in the timing mark being at the being at the left side of the F mark (just as in your case) and appearing to be to far advanced (although it actually wasn't).
Does the Newtronic system use the stock timing advancer?
If it does, then that might be the problem.

steell wrote:

I'm not sure that this is related to the Newtronic ignition, if you advance the timing as you have stated, and the bike runs better, what does Newtronic have to do with it?
On a whim (actually because I had this neat new dial indicator and a degree wheel to play with), I checked the position of the marks on the timing advancer against actual TDC, and found that the TDC mark was actually a few degrees after TDC. Setting the timing accurately resulted in the timing mark being at the being at the left side of the F mark (just as in your case) and appearing to be to far advanced (although it actually wasn't).
Does the Newtronic system use the stock timing advancer?
If it does, then that might be the problem.

I really appreciate your input.

Yes, it does use the stock advancer. That's one of the claimed benefits.

I kinda had a suspicion that it's really ok, but I thought I'd drop them a line and see if they've heard of this symptom, and to be sure that I have the correct pickup unit (since I got the wrong brain unit).

But since you mentioned it, I'll see if I can dig up a spare advancer (or maybe the one off my second 750) and give it a spin...

Thanks again...

I had the exact same problem when I put the Newtronic system on my '78 750. It's set the same as yours Biquetoast, just a smidge to the left of the mark. Seems to run okay there, but I was never sure myself.
I set it dynamically and when it was on the mark it didn't run well at all. Major hesitation.

Not helping much, but letting you know you're not alone on the matter.

Sixgun wrote:

I had the exact same problem when I put the Newtronic system on my '78 750. It's set the same as yours Biquetoast, just a smidge to the left of the mark. Seems to run okay there, but I was never sure myself.
I set it dynamically and when it was on the mark it didn't run well at all. Major hesitation.

Not helping much, but letting you know you're not alone on the matter.

Thanks for the corroboration!

I actually have been emailing Shaun at Newtronic back and forth today. He is a very friendly support guy...

If you don't mind, I'll pass along your anecdote...

I had to resurrect this old thread for sake of closure.

While doing my winter projects , I believe I solved..., no I *know* I solved the "stammering" problem with my bike. I can't tell you how relieved I am, and how well my bike runs now. Thanks to all the advice of everyone involved.

Allow me to paste the follow-up email to Shaun form Newtronic, which should explain everything:

<EMAIL TO SHAUN>
Shaun -

Here it is, another half a year later since we exchanged the email thread (below), and I have figured out what is wrong with my bike and wanted to let you know in case it might help others...

The good news is, it has nothing to do with the Newtronic ignition, which is still running strong. I am now certain the problem stemmed from an excessively loose cam-chain slipper adjustment.

Over winter, I decided to finally attack my cam-chain adjuster (which at first attempt had been frozen). I feared it would break, so I was trepidatious to say the least. Anyway, once at it, it loosened with some penetrating oil soak for a couple days. Once I adjusted it, and took it for a ride, I quickly realized the timing was off now (as I explained in the past, I had retarded it to compensate). Once back in the garage, I set the timing correctly, and now it is absolutely amazing.

So, I'm writing to thank you for your time in the past, and hope that this insight can help you resolve a future problem with somebody else. ...And to let you know I am a loyal Newtronic customer and advocate.
</EMAIL TO SHAUN>

It's always good to see that things work out in the end. Sometimes, it just takes a little hunting.

Hey Biquetoast thanks for the update!

As you can recall I was having the same issue you were and solved it in the same manner. Looks like I'll attack the tensioner now.

Is your timing right on the mark now? I've still been experiencing some popping and burping on deceleration and have always wondered if the intentional mis-set could be part of the problem.

Thanks again!

Sixgun wrote:

...Is your timing right on the mark now? I've still been experiencing some popping and burping on deceleration and have always wondered if the intentional mis-set could be part of the problem...

The timing is now set RIGHT on the line. And what a joy. And only one nice day to rider it and then a week+ of snow and cold!! ARG!

As for your popping, it sounds like your running lean to me... try another 1/4 turn out on the pilot screws...

I can't believe I'm following up to this thread again. But I must...

I thought the problem was gone, but it wasn't. One the bike *truly* warmed up, the problem "stammering" returned lightly and intermittently.

(EDIT: In hindsight, I just want to mention that each individual "stammer" at this point was less severe, and I believe this was because the camchain was properly tentioned...)

There was only one thing left: the coil.

Anyway, I just bought a new Dyna coil from This email address is being protected from spambots. You need JavaScript enabled to view it.. That solved the problem once and for all. I installed it and it started and idled like never before - a sooper-smooth puttputtputtputtputtputt... I rode it for miles and miles in the city to be sure it warmed up.

Rides and runs like a dream.

So it was a bad coil all along as the root cause. All the other stuff I did just made the bike better, which is not such a bad thing.

Case closed.

Post edited by: biquetoast, at: 2006/04/07 08:48

Always good to hear of a tough nut cracked. Good job, Bique.

- Nate >>

Excellent thread. I moved it to electrical since it is entirely ignition related. wg KZr Mod