Recent comparison new power arc vs tri spark

Has anyone heard anything about the new (this year I think) power arc vs tri spark. I looked and the last comparison I saw was at least 4 years old. I know there is a new power arc that has either come out or is about to come out. I'd like to replace an old Boyer. Are there any good (new) magnetos with an advance unit, centrifugal or otherwise. Had an old Lucas mag (centrifugal advance if I recall) on a Matchless Norton in the '60s and it started easy. No battery, no battery worries. Well, maybe the passage of time has made it look better tban it was. I dunno.

Not heard of much on comparisons, but as wanting the programmable version of trispark... I'm building a 11:1 combat cam atlas and I'll need to custom rein in the advance curve, to run our crappy USA EPA E-10.
I have only a little curiousity on the street products, such as the advance curve...

New Joe Hunts don't need advance unit to get them to run, they start first kick every time and will keep full spark till your motor goes bang, I have been running my JH for over 6 years now on my hot 850 and will never go back to any other ignition system ever, they are so good and the best thing no need for a battery to run your bike and if others say they need advance units then they have never owned or run a JH before, I have run them on my old Triumphs without any problems with advancing them, the faster they spin the bigger the spark and they idle great.

Ashley

Well I'd like to ask the magneto guys: Anybody have problems with those? Nice even tickover at idle? Or slow cruise? Pull strong from a reasonably low rpm without knocking? I guess it's true they cost a lot. I think I could put up with one hanging off the side if it was an easy install and just ran -- like ran forever (at my age forever is probably not too far off).

ashman said:

New Joe Hunts don't need advance unit to get them to run, they start first kick every time and will keep full spark till your motor goes bang, I have been running my JH for over 6 years now on my hot 850 and will never go back to any other ignition system ever, they are so good and the best thing no need for a battery to run your bike and if others say they need advance units then they have never owned or run a JH before, I have run them on my old Triumphs without any problems with advancing them, the faster they spin the bigger the spark and they idle great.

Ashley

Click to expand...

Are you saying that there's no centrifugal advance and that they're running at full advance all the time?

JimNH said:

Are you saying that there's no centrifugal advance and that they're running at full advance all the time?

Click to expand...

He is. He says it quite a lot.

Makes you wonder why all other ignition systems bother with an advance/retard system.

Joe Hunt magneto advance curve. Never had one, but a friend that has used one for years sent me this link.

http://www.jcna.com/library/tech/images/tech0015i.jpg

But thats a curve for a BMC Mini engine which has a distributor with vacuum advance and bob weights.

The Joe Hunt Magneto for Nortons does not have an advance mechanism. When used as a replacement for a Lucas mag at the rear of the engine (Atlas, converted Commando, etc.) the stock Norton mechanical advance mechanism is used to provide an advance curve. When used on a Commando and driven off the end of the cam, it has no advance mechanism, and is timed at full advance all the time. I've used that system on a race bike with no issues, but only had a brief experience with it on a street bike. When trying to kick start a high compression 920 with fixed advance ignition, I did have serious problems with kick-back, enough to break the mainshaft first gear on a Quaife gearbox.

Ken

You can have your cake and eat it too. You can set up the Joe Hunt magneto for a Commando with a lever arm that retards the ignition 20 degrees for starting. No kickback. Then flip it back when you're ready to fly. Ashman is right about the advantages of a magneto. I have the Atlas type with the auto centrifugal advance and it starts very easily.

Here's the retard lever assembly for the Commando type magneto (aluminum arm lower right).



PM me for details.

That's a clever mod, and should really help with starting.

Ken

I've gotta get me one of those starter advance covers for the JH mag on my '69 Triumph...

In all the years of running Joe Hunt maggies on my Triumph for over 9 years and just coming up to 7 years on my Norton I have never had any problems with kick back while starting, when I set up the JH on the Norton I static time at 28 d and if I get any kick back I just retard it till no kick back you don't have to move it much at all, I have never used a timing light but normaly static timing is pretty close, my Norton takes one big kick when cold but once started for the day it will start with just a 1/2 swing on the kicker first kick every time.

As for any maintenance I have all my timing marks scribed inside the mounting plate, I set the timing marks at 28 d unbolt the maggie from its mounts and work on it on the bench then when I put it back on in the same position the timing is still set without retiming it, but in nearly 7 years I have only pulled it off for maintenance once, every oil change I pull the front cover off to put a few drops of STP on the felt to lube the points cam, but with the JH the plugs are set at 18thu instead of 25thu as standard.

One day I was coming home from work I was just down the road from home when my Norton got a slite misfire, I looked down to see one plug lead had come out of the maggie cover and the lead was hanging about 2" from the cove but the spark was jumping from the cover to the lead, the bike was still firing on both plugs with just a misfire on the plug that came out, I could see the spark clear as anything jumping, I didn't stop till I got home, I was very impress, it happened the first week of putting it on my Norton.

The new JHs have 4 rare earth magnets where the older ones were 2 rare earth magnets, I have been zapped with my old Triumph JH and I can tell you it friggen hurts, I don't even want to think about getting zapped by the one on my Norton.

Ashley

I've done a lot of reading up about magnetos. Obviously, the retard lever which a few magnetos have is there to cure a design fault in magnetos, which is not having an advance mechanism. Some older magneto designs had an advance mechanism, but for some reason that design wasn't carried forward into most modern magneto designs. (although I did find some which have an advance mechanism)

Not having an advance mechanism doesn't lend itself to stop and go engine use as much as it does to power up and stay powered up engine use. This later type of engine use minimizes the need to have an advance mechanism and it's why a magneto's simple, more reliable design has no real disadvantage in engines on an airplane, some race vehicles or a lawn mower.

On a vehicle that has to stop and start, I want an advance mechanism. If it was an advance mechanism on a magneto that would be ok too.

When my dad was a kid, he learned to drive on a car that had an advance lever on the steering wheel, so as the engine sped up, you advanced the spark timing. To start the car, you retarded the lever or the car would backfire.

So,.... my question is,..... IF an advance curve is a good thing, (but obviously not essential) why don't modern magneto incorporate an advance mechanism into them? Look at some of the 70's and 80's car distributors. Many of them have a simple vacuum advance or bob weights. Why don't magnetos have that simple advance mechanism of some sort??

o0norton0o, in your post you said you found a few modern magneto designs with an advance? I could not find any. If you can tell what they are, I'd like to look them up -- if they can be easily mounted on a '74 850. Also previous post says NO problems with starting at 28 degrees advance(after small trial and error adjustment for residual knock). Any one else have experience with this? By the way I originally wanted to find out about the brand new power arc, but this has morphed into a mag discussion. Actually I'm very happy about that, but if anyone has info about the new power arc I'd like to hear that too.

Sorry about taking over about new maggies but in 41 years of owning my Norton and gone through 3 electronic ingnitions with 2 failing so far from home, but my last Boyar lasted 30 years trouble free and as far as I know its still on another Norton that I gave it to a friend who since sold it, I have no knollage of the newer EIs but I run my Norton without a battery or at the moment setting it up to just run a very small battery just to have brighter lights when running at night.

As for my JH maggie my Norton is set up as a hot street bike with a hot cam, balanced crank for the Featherbed and lots of head work and Jims PWKs carbies which work really well with the JH, it idles evenly with a bit of a lump with the cam and will go from idle to flat out without any problems, as soon as I screw the throttle open it takes off instantly, usualy with the front wheel lifting, have so much fun on this bike, but I can also ride around town happly on 40 mph in top gear without any problems, my motor runs very freely and the JH has no problems keeping up with it, I can sit on the bike to kick start it and like I have said before many times it will start with only 1/2 swing on the kicker once its been started for the day all day long, but I do have the longer kicker on my bike which also helps.

When I am in the shed with a few mates having a few beers we play a little game, who can kick start my Norton, its so funny watching them try to start it, with the compression they all have troubles and give up after a 5 or 6 kicks, I jump on with just a short kick and it always fire up, it amases them every time, but to me its so funny watching them try.

In nearly 7 years with the JH I think its only kick back on me 3 times but that is usualy when the pistons are down the bottom of the stroke but it still fired up, the moden Maggies are so good, I think Morris maggies do have built in advance units, some don't like them sitting off the cam but I like it and when people ask what it is, some of the BS stories you can come up with its so funny, as well they run cooler on the side of the motor, its such a beautyfull thing why hide it behind the motor.

Ashley

You are correct about the Morris magnetos, Ashley, at least the newest ones, but they don't make one for Commandos, just Harleys, Indians, Triumphs, and XS650 Yams. Their older ones are pretty much the same as the Joe Hunt, just reworked Fairbanks-Morse units. But Morris now builds their own design, which does have what they call a "start retard" feature, that retards the spark for kick starting, and then returns to full advance as soon as it has started. It's some sort of spring-loaded pawl mechanism, and seems to work quite well. Pretty clever, really. But the Joe Hunt units do not have that, and are fixed advance all the time. More info here

http://morrismagneto.com/

Ken

See the Morris magneto retard advance lever at:

http://morrismagneto.com/?product=mra-g

Be sure they got it fixed now. I bought one a couple years ago. They didn't have it working right and I sent it back explaining what was wrong. The eccentric that made it retard was not aligned correctly. They said they would fix it but I never followed up on it. Morris doesn't make a mag with a mounting plate for the Commando (Joe Hunt does). But the MRA-G cover with the retard lever is supposed to fit the Joe Hunt as well as the Morris. I dropped the ball on magnetos because I've been busy concentrating on products of my own design.

*****************************************************
Here are the instructions I wrote up when I was adapting the Morris retard lever to the Joe Hunt Commando mag:

Magneto Retard lever mechanism

Replace original points with supplied set, install brass eccentric shaft. Turn cam so points are centered on lobe, turn shaft and stop when gap is smallest largest, set points to .020 inch (0.5 mm). Install new gasket and cap, with o-ring(s) fitted to shaft,. Start with largest o-ring. Push down on the cap by hand only to see if the cap closes against the gasket. Then grab the brass shaft with your other hand and push/pull on it to see if it moves up & down. Choose a combination of Orings so the shaft does not move up and down while the cap still closes against the gasket by hand. Tighten the cap screws gently while checking that the Oring(s) pressure is not too great and that the cover closes against the gasket without too much additional turning of the screws.

Next, install lever with set screw against flat, magnet facing down, and adjust height so
that tip of magnet contacts side of cap screw. The magnet keeps the lever in the advanced
position. Operate lever; if Oring(s) are too tight, they may squish out of place, and lever
will spring back rather than "stick" to the cap screw. Use low strength loctite on set screw. Remove lever when removing cap. For full retard, flip lever clockwise all the way to side of cap. This will retard your engine approx 20 degrees for starting.

Jim

Hi Jim

I really can't see why it needs to be retared for start up as I have always said my Norton fires up first kick every time with the JH advanced without retarding it, the same with my old Triumph with a JH was the same always started first kick every time, seems a lot of stuff you do that is not really needed, I have watched your video of you kicking your Atlas with the JH and my Norton will do the same over and over with the stock JH so I can't really see the fuss over retarding it for start up.

Ashley