Boyer Bransden vs. Tri-Spark

Danno · Dec 14, 2019

Two Boyers here, one over 40 years old and never a kickback from either. Both bikes are 1-kick starters unless the operator screws up and floods one.

MexicoMike · Dec 14, 2019

Triton Thrasher said:
For being the cheapest electronic ignition, that Wassell kit appears to be pretty professional.

My Alton alternator isn’t energetic enough to power it at slow idle or kickstart rpm though.

Are you sure the Alton is working properly/good connections, etc? Mine has no trouble providing power at idle though perhaps the TriSpark uses less...I don't know about the power consumption of the various EI's. I do know that the OEM ignition takes considerably more power to operate than the TS due to the ballast resistor.

maylar · Dec 14, 2019

illf8ed said:
Check into Boyer versus combat spec. It’s been a about 18 years since someone maybe in this site recommended not to use Boyer on a combat engine due to the advance curve. I was getting some detonation with the Boyer and switched to a Lucas RITA. Cured the problem and I put the Boyer in my ‘74 JPN....worked fine.

My buddy has been running a Boyer on his Combat Interstate for 20 years with no issues. He keeps his battery charged.

maylar · Dec 14, 2019

MexicoMike said:
I do know that the OEM ignition takes considerably more power to operate than the TS due to the ballast resistor.

Not true. The ballast resistor and one coil draw the same current as two 6 V coils in series or one 12 V coil. If points draw more power than EI it's because the dwell time is longer. The ballast has nothing to do with it. Also, it's possible for a points set to be closed with the engine not running, which would draw constant power. That's what the "sleep mode" in EI systems eliminates.

Triton Thrasher · Dec 14, 2019

MexicoMike said:
Are you sure the Alton is working properly/good connections, etc? Mine has no trouble providing power at idle though perhaps the TriSpark uses less...I don't know about the power consumption of the various EI's. I do know that the OEM ignition takes considerably more power to operate than the TS due to the ballast resistor.

The Alton dynamo replica is working as well as it ever did, certainly better than the previous 3-phase version.

Not charging at idle can’t really be called a fault.

Tornado · Dec 14, 2019

Triton Thrasher said:
The Alton dynamo replica is working as well as it ever did, certainly better than the previous 3-phase version.

Not charging at idle can’t really be called a fault.

How is your 2MC capacitor? I would think poor idle or no starting at low battery might be a bad capcitor (thats its purpose afterall).

MexicoMike · Dec 14, 2019

maylar said:
Not true. The ballast resistor and one coil draw the same current as two 6 V coils in series or one 12 V coil. If points draw more power than EI it's because the dwell time is longer. The ballast has nothing to do with it. Also, it's possible for a points set to be closed with the engine not running, which would draw constant power. That's what the "sleep mode" in EI systems eliminates.

On my Commando with the points/ballast resistor/twin oem-style 6V coils, the charging voltage available to the battery is one volt less at all RPM than it is with the TriSpark using the same pair of 6v coils. I removed the TS last year/put the points/AAU/ballast resistor in specifically to test that and then put the TS back in.

maylar · Dec 14, 2019

MexicoMike said:
On my Commando with the points/ballast resistor/twin oem-style 6V coils, the charging voltage available to the battery is one volt less at all RPM than it is with the TriSpark using the same pair of 6v coils. I removed the TS last year/put the points/AAU/ballast resistor in specifically to test that and then put the TS back in.

It's certainly possible that breaker points ignition draws more average current than an EI, but it's not due to the ballast resistor. A 4 ohm load is a 4 ohm load. I wouldn't think that a wasted spark system would draw less than a full up 2 cylinder system like stock, since we need the same number of sparks per minute, so the only other thing is the dwell time - the amount of time current flows through the "switch". That would affect the average battery current at any given rpm. I'm surprised though that it showed up as an additional drain on your charging system.

MexicoMike · Dec 14, 2019

Well, if it's dwell related, widening the point gap would reduce the current draw though too much of that would, of course, reduce the time for coil saturation. I had assumed that the primary system resistance was higher with the ballast resistor in the circuit but had never measured it.

Supercat · Dec 14, 2019

I installed a TS last spring and have not had any kickback so far.

Triton Thrasher · Dec 14, 2019

Tornado said:
How is your 2MC capacitor? I would think poor idle or no starting at low battery might be a bad capcitor (thats its purpose afterall).

I have no capacitor in circuit.

maylar · Dec 15, 2019

MexicoMike said:
Well, if it's dwell related, widening the point gap would reduce the current draw though too much of that would, of course, reduce the time for coil saturation. I had assumed that the primary system resistance was higher with the ballast resistor in the circuit but had never measured it.

I've never measured a ballast either, and don't have one handy, but have always assumed it's the same or close to a 6 v coil primary resistance. Points ignition is a huge compromise between a host of factors, including the problem of contact "bounce" at high RPM. Still, I'm surprised that you noticed lower battery voltage with them.

Boyer Bransden vs. Tri-Spark

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