Ignition Amplifier for points

[John A]

For a top notch points replacement an old timer taught me to custom radius the points rubbing block so the contour matches the point cam. I even have a set of grinders that you put over the cam and with the points in place turn it and slightly grind the rubbing block.the theory being that the point gap then would not change as it wore in. I have used them once in twenty years so I can't say it makes a difference, I only post it for the curiosity of it. Now if a guy was racing with a points type ignition it would be great!

[sign216]

Spokes,

I bought a high performance coil, but the manufacturer recommended not using it on a single cylinder bike.  The dwell would be too great, leading to coil overheating.  I bench tested the coil, it seemed okay, but decided not to go that route and stick to the tiny little 6v original coil.  Adding a resistor and all, just to make the high performance coil work, seemed like inviting trouble.

In another vein, when making the bike roadworthy, I added a modern Bosch platinum spark plug.  After getting the system ready and kicking it over, no spark.  Double checked everything, still no spark.  I put the original 50 yr old rusty Marelli plug in, and spark!

It seems the modern Bosch plug was a resistor plug, w an enlarged modern gap.  The old system couldn't handle it.  The modern plug came gapped at 0.95mm, while the bike’s manual asked for 0.66mm.  The extra gap and 5k internal resistor was too much. 
Internet shows 30,000 volts per 10mm gap, so;

modern plug  0.95mm = 28,500 v  add 5,000 internal resistance for total = 33,500 ohm
original plug  0.66mm = 19,800 v

When I reduced the gap of the fancy Bosch plug it sparked, but I ended up using a non-resistor Champion plug with a projected electrode, to help ignition.  The system was designed for a non-resistance plug, so I'm going w that.

Joe

[wirespokes]

Joe - so after all that discussion about what coil to use (and that was the main point through all five or six pages) it didn't get used in the end anyway. And the ignition amp kit only got converted from 12V to 6V. 

At least the maintenance interval on the points has been extended. And you learned (me too) a bunch about points ignitions.

[Rough Edge racing]

 I ran a multi spark CD ignition box triggered by points on a much modified vintage GMC 302 inline 6...But the amplifiers? What exactly is it supposed to do? Some of us  50 years ago had nothing but points ignition in  V-8's having 50 cubic cylinders and 11-1 compression at 7000 rpm...If you keep on top of the tune it worked ok...
 It was my experience with 750 Ducati's and a Guzzi, the points last a long time and tend to stay in adjustment.. Servicing the distributor on a Tonti frame is easy with the fuel tank pulled off..Sit on a chair with a bright light and take your time. A chance to feel the engine and imagine being an Italian race mechanic..If it's too much trouble, buy a Camary...........Or fit an electronic ignition..

[sign216]

At least the maintenance interval on the points has been extended. And you learned (me too) a bunch about points ignitions.

Spokes,

Adding the transistorized ignition was to improve running, esp idle, which it did.  Maintenance interval is a secondary benefit.

Situation: 1960's Benelli/Wards Riverside 350 single, idles about 1,300 -1,600 rpm, in good tune.  On a Riverside forum they said that's normal, but one experienced man said he was able to get his idle down to 800-900 once he fitted a full electronic Powerdynamo system; charging, ignition, everything.

I wanted to keep my bike stock, so adding a transistor assisted ignition was a way to slice that pie.  I posted on the electronics forum (in different thread, Wirespokes, of only two pages);  https://www.electro-tech-online.com/threads/ignition-coil-and-idle-speed.153960/

The transistor assisted ignition was a help, bringing idle speed from 1,300 - 1,600 rpm down to a reliable 1,250 - 1,350.  That may not seem like much, but  a single cyl going at 1,500 it feels very high. 

One question, never answered, is why?  These bikes have battery + coil ignition, so idle speed shouldn't be stressful (unlike magneto ignition).  I never figured it out, but was happy that the transistor assisted ignition improved the performance.


On the performance coils;  they are made for multi-cylinder 12v engines, and not suitable for vintage single cyl. 6v bikes.  Yea, Wirespokes, I might have been able modify the system for a new performance coil, but I tested the performance coil I bought, and there wasn't any spark improvement over the 50 yr old orig coil.  Here's a question:  60-80 yrs ago, when 6v single cylinder bikes were raced, did they use factory coils and ignitions, or did they have performance parts back then for them?

Joe

[guzziart]

There is a special grease, also look at the cam that the points rubbing block rides on. Rust/dings?

Yogi, cam is like new, no sign of any oxidation even at the advance mechanism moving parts (lubed too).  When I said I adjust between 5-7K mile intervals, it is because ( if I remember correctly) the gap has diminished a couple thou to 0.012 or 0.013",  I think the clearance should something like 0.014-0.017" so, if I'm taking the time to remove to dist cap to check and it is out slightly, I'll readjust.  Then spend another half hour to check timing, sync carbs, idle, etc. so I'm good to go for another couple years or 5/7K.  And the bike runs remarkably better.

Spokes....To answer your earlier question about points, I don't remember if I had to draw a file across the contacts because of material transfer.

OK, Happy Sunday to All!

[wirespokes]

I'm used to points gap changing and mileage going down, at about 3K miles or less. Being able to go 7 to 10K (or more) sounds wonderful to me. I can't imagine how long the points would last with an amplifier.

sign - I'm guessing spark intensity must be pretty poor at low RPMs with that system. 1250 to 1350 seems pretty high for an idle, but then it must sound fairly slow considering the number of exhaust pulses. It would sound slower than my twins idling at 900 RPM.

[garbln]

The big advantage with an "amplifier" is there is only milli amps going thru the contact points so the surfaces don't burn out.  However the ware blocks on the points will still ware down so they must still be checked occasionally they just don't burn out anymore.  As an aside about Condensers, if the buildup or mound is on the pos side of the points the condenser is too small, if on the neg side its too big(electrically speaking uf size).   

[Stevex]

When I did my LM2 rebuild I looked into the Velleman kit and even bought two and built them up.





I mounted them on a paxelin base but never installed them; firstly, space was a problem, especially with two of them (one for each set of points).
Secondly, insulation; I sprayed electronic lacquer on them but they really needed to be enclosed to keep moisture / rain out, which would have made the end product even larger.
Have to say I've never had a problem with the original points ignition either and once they're timed using correct timing marks on the flywheel, it gets even better. I checked the original timing markings with a timing disc and piston stop, they were all at least 2 degrees out. When I fitted the lightened flywheel, it got stamped with perfect timing marks.

[wirespokes]

Steve - good point. It would be difficult finding a place for two big amplifiers.

I've heard that about mis-marked Guzzi flywheels. I probably should verify TDC first, then measure to static and full advance. I'll have to research how many teeth equals X amount of degrees.

garbin - I've never gotten that deeply into condensers. The next question is if there's a mound building up whether the current condenser is malfunctioning. Back in the day I'll bet everyone knew that bit of data about which side buildup was caused by what. Thanks for that!

[sign216]

Spokes,

The idle still sounds high, but there aren't any orig specs for the right idle speed, and some references say that's within the normal range for a single cyl engine.  See Wikipedia "For many single-cylinder motorcycle engines, idle speed is set between 1200 and 1500 rpm. Two-cylinder motorcycle engines are often set around 1000 rpm."

As for the spark, it's actually a strong spark, as long as you keep within the parameters it was designed for, mainly in keeping a closer (0.6mm) plug gap.  That plug gap is actually common for older cycles.  I've heard that with modern lean tuning for emission, they widened the gap to help the engines run with the lean mixture.

Let me know if you use the transistor assisted ignition units, and how it works out for you.

Joe

[rodekyll]

Keeping the iol pressure up is one reason for a higher than expected idle.

Ideally points wear "flat".  The mound, or fang, grows as metal is removed from one side of the points and microwelded to the other.  As stated above, the lumpy side tells you if the condenser is over or under sarurating.  The fang needs to be filed off to get the true gap.

Dwell isn't much of an issue on a single or twin other than that it affects timing.  Dwell is necessary to allow the coil time to saturate.  Anything from .012 - .025: ought to work.  Dwell becomes more important as you move into multi-cylinder engines.  If you have a guzzi dizzy that won't time at idle, changing the points gap is one way to dial it in.

[sign216]

When I did my LM2 rebuild I looked into the Velleman kit and even bought two and built them up.





I mounted them on a paxelin base but never installed them; firstly, space was a problem, especially with two of them (one for each set of points).
Secondly, insulation; I sprayed electronic lacquer on them but they really needed to be enclosed to keep moisture / rain out, which would have made the end product even larger.

Steve,

I was able to enclose my Velleman and mount it on a much smaller bike.  Take another look.
And...
Hmm, I think you could use one unit, wired to fire both points.  Come'on, you've already got the units assembled. 

[wirespokes]

How could you fire both coils with one amp if not wasted spark? I'm sure there's a way, but some mods would definitely be in order.

The amp goes between the points and the coils. How would you keep the two circuits separate on a two cylinder engine with dual points and two coils?

It sure seems like two separate amps would be needed.

[sign216]

The transistor ignition is just a switch, activated by the points.  It is easily activated by two points instead of one. 

Easy enough to try out.

[wirespokes]

True enough - it won't matter, or care, which points activate it. But if wasted spark isn't desirable, how can the output current be directed to coil A first and then to coil B next time?

I'm sure there's a way electronically, but not being an electronics expert I have no idea what's involved.

[sign216]

True enough - it won't matter, or care, which points activate it. But if wasted spark isn't desirable, how can the output current be directed to coil A first and then to coil B next time?

I'm sure there's a way electronically, but not being an electronics expert I have no idea what's involved.

Consolidating wasted spark into one plug would really plus up the ignition current, but the effort and geometry involved is large.  There's a reason Guzzi (and BMW, and who knows who else) use wasted spark.

I respectfully suggest keep the wasted spark, and work on the other areas to improve the ignition current.

Joe

[Stevex]

Wirespokes, did you ever use an amp?
I never did follow up on my Vellemans but have just installed a pair of Gammatronix amps.
They are very small compared to the Vellemans set up.

https://gammatronixltd.com/epages/bae94c71-c5b6-4572-89a1-e89006e78fbe.sf/en_GB/?ObjectPath=/Shops/bae94c71-c5b6-4572-89a1-e89006e78fbe/Products/NewTwinC-12VNEG

[wirespokes]

Two years have gone by already - ??? That was QUICK!

After hearing comments that points can last 50K ignition amps dropped in priority. So no, I've done nothing in that dept.

I'm reluctant setting up the Guzzi in wasted spark mode. I've heard it will run, but I've also heard that with the right conditions, a backfire could set the bike on fire. Not something I want to chance.

The price is certainly reasonable, and I like the size. Let us know where and how you mount them. Keep us posted and let us know how it works out - increased power, gas mileage, smoother running, etc.

[Stevex]

I know that the set up is still points without the condensers, and I'm happy sticking with points, mainly because I can't afford the electronic ignition I'd really like (Sachses). I like the idea that these amps improve the spark and as you say, the price is right. A lot of the classic car owners use these amps too, with improved results over the standard (condenser) set up.
I've mounted mine using closed cell doubled sided adhesive foam; the amps come screwed to the alloy backing plate.

[jacksonracingcomau]

I have to wonder if this is part of the reason Moto Guzzi went to twin points (and if the two lobes in its distributor are the same)

Exactly why, of course there is only one lobe on twin point breaker assembly
Far superior to distributor, no rotor button nor cap, precise control over timing and dwell.
Two completely independent ignition systems, left and right.

[Stevex]

When I "refurbished" my Convert back in April of '17 I gapped the points, set the timing (no modification of the points plates necessary) and greased the cam of the distributor with a little Bosch Distributor Grease.

That Bosch grease doesn't seem to be available from any where in the UK.
I've seen Loctite Super Lube widely recommended and is available here, anyone using it?

[sign216]

That Bosch grease doesn't seem to be available from any where in the UK.
I've seen Loctite Super Lube widely recommended and is available here, anyone using it?

I got vintage distributor lube off of Ebay. 
Basically you want a tacky grease that won't melt under high temps or be flung off.
Lubricam is still being made.

Joe