E: Engine rev counter

[erik]

my Problem is that the rotating parts of the lucas magneto are elektrical insulated to the rest of the motorcycle.if i want to connect a revcounter gearbox this must be insulated ,too.how did you manage this with the standart automatic advance unit?as well the drive force should not be taken from the central Hexagon.this would have an influence on the ignition Timing.regards Erik

 

[greg brillus]

No you do not need to insulate the rev counter drive components, in the magneto it is only the points assembly at the other end that have to be insulated, the main armature is earthed via an earth brush near the drive end. And your other question, well generally a tacho was used with a manual advance magneto. I believe it can be driven via a stock ATD but it sounds messy and you don't want any loose parts coming apart in there. I installed one of the newer BTH magnetos with a solid drive gear set up to drive the tacho on my bike, been on there for some time now with no issues to date.

 

[erik]

your right Greg,i forgot that earthbrush.this makes things easier.but how does it look with this insulated bearings?isnt the whole shaft insulated and only the outer ring where the earthbrush slides on earthed?the contactbreakers can stop working on some mags because there is an other brush in the centre of it for shortcutting.and the tufnol drive is for insulating ,too.

 

[bmetcalf]

Maybe use the PR33/6 - DIGITAL from VOCSC?

 

[Simon Dinsdale]

The bearings in a magneto are insulated to force the electical circuit through the earth brush. Any current going through the bearings could postentially damage them over time and is a greased bearing really the best electrical conductor?
Simon

 

[erik]

@bmetcalf.in the case of a strong solar current you will possibly read wrong informations on your Instrument.this is not my way.thank you Simon for this Information,sounds Logical.this means that a fault in the bearing insulation will not stop the bike? erik

 

[timetraveller]

I don't want to become involved with disagreeing with anyone on this but Greg is correct. You cannot realistically drive a rev counter from the nut in the middle of the ATD or from the ATD gearwheel. Taking a connection from the centre nut will stop the ATD working properly and if you look at the space on the gear wheel around the ATD there is very little left to take a drive from. VOCers are an ingenious lot and I am sure that someone, somewhere will have done what you suggest but it is likely to lead to premature failure of something. I have not seen what the Spares Company offer is like but there are plenty of pulse driven rev counters available.

 

[vibrac]

Were it not insulated all the rev counters in all the Vincents in most of the 20th century would not have worked don't worry .
I only use electronic now anyway.

 

[stu spalding]

your right Greg,i forgot that earthbrush.this makes things easier.but how does it look with this insulated bearings?isnt the whole shaft insulated and only the outer ring where the earthbrush slides on earthed?the contactbreakers can stop working on some mags because there is an other brush in the centre of it for shortcutting.and the tufnol drive is for insulating ,too.

While we're on the subject of insulating ATDs, some years ago a batch of pinions was made in nylon, these should be given a wide berth as they absorb water, swell up, and cause binding problems with the breather pinion. I bought one but was warned off fitting it and it resides in my shed where it has now attained a diameter .050" larger than standard. Cheers Stu.

 

[vibrac]

While we're on the subject of insulating ATDs, some years ago a batch of pinions was made in nylon, these should be given a wide berth as they absorb water, swell up, and cause binding problems with the breather pinion. I bought one but was warned off fitting it and it resides in my shed where it has now attained a diameter .050" larger than standard. Cheers Stu.

As I remember the first batch were fine perhaps even the second batch but then someone went for the wrong type of nylon a great pity a bit like the original nylon bushes for girdraulics the second batch were poor -its easy to get the wrong mixture I guess (I bit like our so called petrol)