CB500T Electronic Ignition

September 2009

As you will know if you read my News pages you will be aware that our Newtronics system expired this month. After a chat with Ray Debben about the Dynatek ignitions, I decided to go down this route, though I knew there would be problems.
Ray reckoned that the Newtronics amplifier had failed due to me using the wrong coils, so besides a Dyna S ignition, I would need a pair of dual output 3 ohm Dyna coils.

I then discovered that the Honda GL1000 Dyna S could be adapted to suit the CB450, and by implication the CB500T .

Tim Blakemore Racing supplied the parts the next day and then began the difficult bit:
One of the pickups had to be repositioned to suit my crankshaft configuration. Unfortunately the pickups ended up fouling the back plate retaining screws and cam follower adjuster nut. I could sort this by cutting a new locating keyway on the auto advance unit, but this is hardened so will have to wait till another time.
Incidentally, the auto advance on the engine was totally knackered and probably went to full advance the moment the engine started, so this was replaced with a lovely new one from David Silver Spares. The Dyna trigger replaces the rotating element of the auto advance, but does not have the little flange to stop it falling off. I had to make a little spacer to allow the auto advance retaining washer prevent this happening.

After many hours of fiddling around it was all made to fit and timed up to perfection. I must say it appears far more robust than the Newtronics system, lets hope so. The rotor has two magnets at 180° so produces a wasted spark. I am not sure if this will cause a problem when running with the supercharger and methanol, so maybe another modification at some point.

I started the bike up one lunchtime, it sounds much crisper and ticks over very evenly . All we need now is some good weather coinciding with a RWYB.

 

   Dyna S ignition as adapated to suit my 60 degree CB500T drag bike

2003

THE CB500T is blessed with 2 sets of contact breaker points on one backplate. Consequently the only way to adjust each cylinder independently is by adjusting the points gap, and once the points have worn a little you are on a hiding to nowhere.

DUE to the possibility of problems with uneven cylinder filling with the 180° crank/supercharger setup, I have been reluctant to go to electronic ignition just in case we need to go to a 360° crank. This of course would require ignition pickups at 180° rather than the current 90°. Anyway we seem to have crossed that particular bridge so I decided to lash out on the Newtronic Systems Ltd. optical trigger system.
This particular system is tailored specifically for the CB500T and I think is the only system available as a bolt on. The other good point is that it works fine with coils up to 3 ohms like the Dyna ones we are using.

THE first stage was very encouraging; I ordered online from their web site on Sunday, had confirmation of receipt of order and dispatch on Monday with the unit arriving Tuesday. The unit was well packaged with pretty good instructions and took about 2 hours to fit, all wiring is designed to plug straight into the Honda loom and though a little fiddly at some stages is pretty easy to fit. A new thicker points cover gasket is supplied along with a spare, there are also spare sticky pads for attaching the amplifier unit; excellent.

I thought stage 6 of the instructions was a little vague; you need to remove the advance/retard bobweights and points cam unit from the engine. Mine was a very tight fit on the end of the camshaft.
The only other point worthy of mention is that it's a good idea to feed the wire from the trigger unit through the back of the cam bearing casting before fitting the trigger unit. Access is a bit limited if you follow the instructions in stage 11.

The facility to adjust each trigger unit independently is provided with slotted screw holes, however the screws are hidden behind the rotating disc. Also I had to cut a piece of the back plate away to allow it to rotate far enough to set the timing right.

HAVING fitted the complete system I switched on and turned the engine over slowly and was rewarded with nice regular fat sparks. OK plugs back in turn the engine over a few time and then a one kick start. The engine now starts so easily and sounds much sharper.

THE VERDICT: Money well spent, that rare commodity excellent customer service, and surely the single best improvement you can make to a Honda CB500T.

Updated 2009: As far as I know the Newtronic system is still no longer available though you can try the site below :

NEWTRONIC SYSTEMS LTD web site.

 

 

  

The optical trigger components

The optical trigger unit, feed the red wire through the casting before installing the assembly. Note the slotted rotating disc.

Graph of Newtronic performance comparison.

Judging by the way the feeble glimmer at the plug has been replaced by a healthy crack on 'The Fang', Newtronic's claims would appear to be correct.