Topic: ARD Magneto

[Terry in Australia]

Ha ha, yeah, I'm a dumbass Rich...

Sorry Terry!     My bad!

They're on the way...4 emails...

Thanks mate!

[puppytrax]

Joe Hunt still makes magnetos, unfortunately not for SOHC4 Hondas...   

http://www.huntmagnetos.com/motorstore.php

But they have an impressive housing for the mags...   



Description: BILLET ALUMINUM HOUSING
Price: $178.00
The all new Joe Hunt Magnetos billet motorcycle housing. CNC machined to match the dimensions of the original magneto housings and take all of the same parts except the lower seal.

They also have a large stock of mag parts, for their mags...

[puppytrax]

Ha ha, yeah, I'm a dumbass Rich...

Sorry Terry!     My bad!

They're on the way...4 emails...

Thanks mate!

I hope that's better...If not, I can hold the magazine up to the monitor so you can read it...   

[puppytrax]

I hope I'm not boring anybody with this...but I'm curious as to whether the magneto setup for the SOHC4 fires each cylinder every time the piston goes up...same as the OEM ignition...that is, each cylinder fires on compression *and* exhaust stroke...   

They don't show the inside of the 4-cyl mag...does it have two sets of points or one??

[Big Jay]

Fires one cylinder at a time.

Jay

[puppytrax]

Fires one cylinder at a time.

...Ha, ha! Yeah, I guess I asked for that one!!!   

Although there used to be Triumph twin conversions called "twingles" that fired both cylinders at the same time...a bloody big "thumper"!!!   

No, what I meant was does the ARD (or RC) conversion also fire on the exhaust stroke, like the OEM Honda ignition does???

[Bodi]

No. It has a distributor (just a normal 4-cylinder automotive type) and fires only one plug/cylinder at a time. The magneto advantages ares that it uses no battery power to operate and the spark gets stronger at higher RPM. Kettering systems use battery power and spark energy decreases at high RPM because of the reduced dwell time.
Mags are used in piston aircraft engines because of the isolation from most electrical problems - a blown fuse won't become a forced landing (also called a crash); aviation engines always have 2 complete independent magneto ignition systems because of the relatively high failure rate of the spinning mechanical devices. Nowadays vintage/dirt bike racers don't use mags generally because the newer battery powered electronic ignitions are more reliable (fewer moving parts), lighter, and work at least as well. Just recharge the little battery every few races and you're good to go.

[puppytrax]

Is there anyone else out there who wants to try one of these?? 

I've been emailing Terry in Oz, and he is of the opinion that the Fairbanks-Morse FM-J4 magneto, configured for CCW rotation (as seen at the rotor), is the base for the conversions by ARD and/or RC. They seem to be fairly plentiful.

The timing belt pulleys and belts can be found at -

http://www.polytechdesign.com/flexbelt.php

http://www.polytechdesign.com/t5_16.php

- among other places.

It looks like a fun project...A round aluminum disk replacing the points cover; an aluminum box to protect the belt & pulleys and mount the mag; and a simple shaft/mag shaft conversion for the pulleys...   

Woohoo!! 

[Sam Green Racing]

Here is the magneto story. We used to be an ARD distributer. At the time, it was thought that firing one cylinder at a time would provide some sort of power gain.  Besides the ARD, there was the RC Eng unit that used a Vertex mag, and Rotofaze made a belt driven distributor which we sold also.

We got deeply involved with a leading pro stock racer back then, and he had Vance and Hines motors that were built and tuned by Byron Hines himself. We had an ARD CDI mag on this bike. Byron did a test on the dyno by taking off the mag and installing a Dyna S and coils.  IT MADE MORE POWER!!!

That is when we quit selling the mags. Wasn't going to sell someone something for $375.00 when a $125.00 product would make more power.

Today, no gasoline burning race bikes use a magneto. Battery powered electronic ignitions simply make more power.

Now as for the cool factor, those ARDs hanging off the side of those Hondas do give them that very 70s race bike look.

Jay

How about a dummy magneto and drive cover with an electronic ignition inside of it

Electronic performance.......magneto cool factor

Sam.

[puppytrax]

That quote cited the "CDI mag". The FM mag is quite different.

But you are right - I am going for the coolness factor. This old bike will never turn heads on power...   

[Terry in Australia]

I'm in Rich, but I'm gonna go "Commando", no faggy belt covers for this little black duck!
How about a dummy magneto and drive cover with an electronic ignition inside of it

Electronic performance.......magneto cool factor

Sam.

 

That's a great idea Sammy, trouble is ARD beat you by about 30 years, with their MK2 version, which was a belt driven electronic ignition, and the magneto was similar to a two stroke dirt bike's (or old BSA Bantam) magneto. Here's a pic of one of my 4 Mk2's on one of my 6 CB750 engines. (yeah, I'm a compulsive Ebayer, ha ha!)

[puppytrax]

I'm in Rich, but I'm gonna go "Commando", no faggy belt covers for this little black duck!

Does the term "bicycle clip" ring a bell??   

I got a couple price quotes on the pulleys/belts - a 40 tooth shielded pulley runs ~$17; a 20 tooth runs ~$9; 410/420mm T5 belts run ~$6...15/16mm widths; all T5 pitch; aluminum...

I have an FM mag; it will nestle into the carb/fins/case space on the right side of the CB500/550...That is where I got the 410/420mm belt length from...   

Need to order some aluminum plate now, too...   

[Terry in Australia]

Good one mate, but you won't need a bicycle clip unless you're still wearing your killer 18" flared disco pants from 1977, that belt is a fair way forward of your daks mate unless you're running highway pegs, ha ha!

Now I reckon to add to the "cool factor" I'm gonna run an open "belt tensioner" on mine, On the MK1 I sold Jim, there is no tensioner, but the belt is a pretty tight fit. But this way, even if your calculations are a little bit out, it won't matter much? Cheers, Terry.

[puppytrax]

Now I reckon to add to the "cool factor" I'm gonna run an open "belt tensioner" on mine, On the MK1 I sold Jim, there is no tensioner, but the belt is a pretty tight fit. But this way, even if your calculations are a little bit out, it won't matter much? Cheers, Terry.

The mag I'm going to use has a 2-bolt flange; one of the bolt holes is slotted...I'm thinking I can get the tension adjusted with that...If not, the belts run in 10mm increments; at ~$6 each, it's not too expensive to dial in the length...

[Terry in Australia]

Now I reckon to add to the "cool factor" I'm gonna run an open "belt tensioner" on mine, On the MK1 I sold Jim, there is no tensioner, but the belt is a pretty tight fit. But this way, even if your calculations are a little bit out, it won't matter much? Cheers, Terry.

The mag I'm going to use has a 2-bolt flange; one of the bolt holes is slotted...I'm thinking I can get the tension adjusted with that...If not, the belts run in 10mm increments; at ~$6 each, it's not too expensive to dial in the length...

Ok mate, I might beed to get back to you to order me a belt and a couple of pulleys once I work out the length I need? Hmmnnn, I wonder if I could make a buck outta these............. ?

[puppytrax]

Ok mate, I might beed to get back to you to order me a belt and a couple of pulleys once I work out the length I need? Hmmnnn, I wonder if I could make a buck outta these............. ?

No problem! I've been in contact with the honcho at PolyTechDesign and have a 40 tooth T5 and 20 tooth T5 pulley coming; as well as two belts [410 & 420 T5]. I was tempted to go bigger on the pulleys, but IIRC, 40 tooth is what my old ARD used...I'm guessing ARD would have used the same on one end of the SOHC4 and half size on the other...   

But I've been wrong before...   

BTW: I'm using the Metric sizes, rather than the Inch sizes...

[Terry in Australia]

Thanks mate, I'll measure the pulleys later, I think the ones on the Mk2 are different from the Mk1, the belts are, Jim sent me some but they're too long. Cheers, Terry.

[puppytrax]

Here's a piss-poor pic of the relation of the mag to the crank...This is a CB550K engine...I figure I need a 1" x ~5.25" aluminum spacer on the case to get the mount out to the right a bit...and a crank extension/pulley shaft for the crank pulley...

This is an FM mag, but not the one I'll be using (it's just for mockups)...   

(Ignore the rubber bands...they'll be replaced)   

[Terry in Australia]

Very nice Rich, the mag looks right, it's just like one I've got in the garage. I'm going to machine a round "disc" the same OD as my points cover and install an "outrigger" bearing for the drive shaft to keep it free of wobbles and to add some strength to the whole plot.

I was gonna go buy a slab of alloy billet for the "arm" today, but my local supplier is closed for the "Australia Day" long weekend, so I'll have to wait until they re-open. No biggie though, I've still got plenty of work on the K1 to keep me busy, ha ha! Cheers, Terry.

[puppytrax]

I'm going to machine a round "disc" the same OD as my points cover and install an "outrigger" bearing for the drive shaft to keep it free of wobbles and to add some strength to the whole plot.

Same here for the "disk", but do you really think it needs a bearing??    I can pretty much twirl the magneto shaft with two fingers, and I don't plan on the belt putting any appreciable tension on the extension...   

I was planning on a 1" thick doughnut with 5 screws holding it on; then screw a 5" x ~10 piece of 3/8" aluminum plate to that for the mag mount...I'm making a sheet aluminum template/mockup now...

It will be "open air" until I can find some 3" electrical conduit [aluminum] to use for end pieces...for the beltbox...   

I want to see that spark snapping across the gaps...   

[Terry in Australia]

Same here for the "disk", but do you really think it needs a bearing??   

Yeah mate, the ARD CB750 mags all have them, and I suppose that the belt is under tension on a pulley hanging off the end of a long-ish shaft. It's not gonna be too hard though, I'll just bore the centre of the "donut" to accommodate a sealed bearing for the shaft to pass thru. Cheers, Terry.

[puppytrax]

Yeah mate, the ARD CB750 mags...

Terry - I took this "mockup" FM mag apart (it's an FM-X4E3; turns CCW) to find out what that spring thing on the drive shaft was...it looks like some kind of advance assembly...

My old ARD Triumph magneto didn't have any advance mechanism; the pulley mounted right on the tapered magneto drive shaft...

Do the ARD Honda mags use an advance, or does the pulley mount directly to the shaft?? 

I'm wondering why I couldn't just take the advance mechanism off and trash it, and run the magneto CW...I can't see why the mag would care which way it's turning (with no advance)...   

I recall an old magazine article, where the author had an old motorcycle with a magneto...(I don't recall if it was a Britbike or not, or whether it was 2-stroke or 4)...he tried to start it, and it kicked back, and started in reverse rotation...so he put it in gear and backed up 15 or 20 feet just to blow the other riders minds...killed the motor, and restarted it in proper rotation and rode off... 

[Terry in Australia]

G'Day Rich, yeah mate, I've heard of that happening with old 2 stroke engines, for sure.

The ARD's for CB750's ran at full advance all the time, and while that's fine for drag racing, there are a few old guys out there who've told me it wasn't ideal for commuting, particularly if you had to kick start the sucker on a wet day!

If you can keep the advance unit I reckon it'd be an advantage, even if you have to have an "old school" ignition advance lever mounted on the bars, most magneto's I've seen are advanced/retarded by turning the actual magneto body, so I guess this wouldn't be too difficult considering we're not modifying an existing unit with it's own design flaws, but starting from scratch? Food for thought, if nothing else, ha ha! Cheers, Terry.  

[puppytrax]

The ARD's for CB750's ran at full advance all the time, and while that's fine for drag racing, there are a few old guys out there who've told me it wasn't ideal for commuting, particularly if you had to kick start the sucker on a wet day!

Terry, I never had a problem starting with my ARD Triumph conversion. It also used a locked advance, IIRC 40* BTDC...

Got my aluminum yesterday. 1" plate for the cover, and 1/2" plate for the mount. I wanted 3/8", but the Government Job supply depot only had 1/2" in stock...   

Managed to hog out a ~5 1/2" disk; need to turn it round then cut the 90mm x .090" step for the three inside 5mm screw bosses...

I love the smell of metal shavings in the morning...   

[Terry in Australia]

Excellent Rich, make sure you take plenty of pics so I can see what you're doing, (I think only you and I are still interested, ha ha) and if I get a chance to take a break from finishing my K1 and building oil cooler adapters this weekend, I'll start on mine too, woohoo! Cheers, Terry.