An introduction and question about ignition

Hi,

I got my first Norton in 1966 at college. It was an Atlas scrambler that had been cafe'ed with low bars and a few Dunstall parts.
After that I had a couple of early Commandos, wiping one frame and a couple of engines out in local club races. I guess they really mean RPM limits.
I modified my 71 Commando with oil in the frame, a large oil tank, pontiac oil filter, and slightly lower compression. She made it cross country and was my only transportation in SF for a few years until I gave it to a friend about 1995. I thought I was done with bikes for life then.
I now have six bikes and am building an extension on my garage.
I just bought a modified Norton from my little brother which is why I'm on here today.
It has been in the hands of one or another of our family and friends for a number of years.
I think the frame is a 1964 Atlas featherbed and has been fitted with about a 72 Commando power train and brakes. "Com-bed"? It uses nearly all components I recall from my early bikes down to the mufflers.
I rebuilt the 30 mil Amals on Saturday and now I'm getting kick back from the Boyer Mark 3 Norton version electronic system. It seems to be wired correctly and has over 13 volts to the input. It does not power the coils until it gets input from the pickups but I am getting a spark too early before TDC. My brother says once running it is fine.
Tonight I was thinking of retarding the Boyer a bit and if that did not work I'd try a battery with lower voltage. This is a gel power cell in it now.
Is this kickback a known issue with the Boyer system? Is there a common cure?
This is my first Boyer and it does not have directions of course.

Thanks in advance,
From San Mateo, CA

The kickback is a symptom of low battery voltage or one or manyof the following (hence your 13V Gel should stay in the bike, 13V is good).

Over advanced 5000 rpm setting which could come from setting the timing at 3000 rpm instead of 5000 rpm.

The degree plate in the primary cover is giving the wrong reading, check by using a degree wheel to set 31 BTDC and then replace the cover and see what that says (it will not be 31 :roll: )

Your Boyer box is retarding too little at low revs out of the box due to variation between boxes. Image courtesy of Dave Comeau and Ludwig

Welcome Cookie,

[Edit](kommando posted while I was typing)


A Boyer causing kick backs when starting can be caused by low voltage, but you've checked that, so it sounds as if it could be set too far advanced, or maybe there is a bad wiring connection or a bad switch contact causing an intermittent connection problem?

Have you checked the ignition timing with a strobe yet? The Boyer needs to be set to 31 degrees BTDC fully advanced @5000 RPM? (points ignition would be 28 deg. @ over 2000 RPM) and use the strobe to check that the Boyer is advancing reasonably smoothly as the revs rise.

The instruction sheets are on the Boyer Bransden website: http://www.boyerbransden.com/instructions.html so I would recommend you use the Mk3 instruction sheet to check everything is correct, along with the Boyer fault finding information: http://www.boyerbransden.com/faultfinding.html

I hope you will let us know how you get on?

Thanks gentlemen

It sounds like I may be on the right track then. After work I'll check to see if I have good connections from the former points area and that everything is firmly mounted.
I'm glad to know that over voltage would not likly cause this because that eliminates one area to pursue. Yesterday I saw my first Boyer ignition and now I'm already on my way to becoming friends with it.
Those links should help a lot.

I once put an Atlas crank in a Commando I'd blown up and nearly kicked my leg off before I figured out how to degree the thing in. I'll see how this goes this evening. I no longer have a degree wheel but there may be one in my future.

Cookie said:

I no longer have a degree wheel

Click to expand...

Downloadable degree wheel: http://www.tavia.com/free_degree_wheel.html

Battery Battery

Hi
Had a lot of trouble starting the race bike & we had to retard the ignition to get it to start. Atlas lump 29* on the bench. Keith said its the battery its always the battery. We tested it & had 12.47 .charged it for a short while & up it came to 13.4 & the bike started on the original settings. Point proved lesson learnt.
all the best Chris

Thanks guys

I just heard the music of my youth.
I tested it down with a multimeter and all connections would have run. I did the old wiggle the wires trick and they are solid. Next winter I'll rewire it though as it has 12 connectors just from the pick ups to the box.
I mounted the Boyer box with Velcro and replaced one connector I didn't like with an exposed piece of wire.
I used the hex wrench I was checking tightness with to determine rotation, marked it on the case with a scribe and made a mark on case and plate to determine starting point. I eyeballed a degree and retarded it figuring cam rotation is faster than crank.
After sandblasting the plugs and re-gapping same I put on the fuel tank to try it.
When I ticked the carbs they really were tickled and the right one puked fuel even after I tapped it. I know I should seal an old fuel tank but I didn't.
Ok, pull off the crossover and float bowl, sure enough brown tiny rust.
Reassemble promising to seal it in the winter. I sealed three last winter.
On the second kick she fired right up.
When I told Chris in Hayward I was going to buy this bike he said it was the worst combination ever. The Commando engine is balanced for a Commando and she was bound to be a shaker. She tries to go back and hide in the garage at idle. With a small angle the vibration will walk her backwards on the center stand.
Right now I have everything set by eye and ear and I have been able to determine all her basics are still good. I was afraid of stuck rings or even rusty bearings but the engine seems solid.
I was wondering if I was going to have to go through it but it looks like she will do the job with a bunch of the usual work an old bike that has been sitting needs.
On the punch list are a leaking right exhaust to head connection.
Tach does not work.
Seal fuel tank.
Install mirrors.
Rewire sometime.
A few missing bolts and nuts.
Centerstand spring, she has a bungee cord there now and not even an English one.
A proper winter morning tune up.
Oil change.
I'm sure I have forgotten something.
Thanks for your help guys.

The old Norton thanks you too.

A few things to add to the repair list. The rear brake light switch and carb slides.
I have a one kick starter now and much smoother but still balanced wrong bike. It has lived this way for years and the engine feels very healthy and does not smoke. Should l I blow it up I'll use an Atlas crank, but since I became eligible for the senior discount I don't blow engines much.
She won't quite tune right, a little uncontrolled burble on the right. When I touch the slide it changes so slides here I come.
Last night I gave it a new battery mounting system inside the stock box to hold the power cell steady. Earl took it out of a UPS system so it is far from stock size. It now has an alloy base that holds a Velcro strap with a rubber bottom to absorb vibration.
Today she got Redline 20-60 motorcycle oil at ten bucks a quart, she does not hold much so the tougher the better.

Cookie said:

Should l I blow it up I'll use an Atlas crank,

Click to expand...

The crankshaft balance factor can be altered to suit the featherbed frame?

We will let experts here correct my leaky old memory because I did this years ago.
I blew up my Commando in a local knee scraper and I had a friend who had some Atlas parts.
I had the Commando case welded to reuse and some fins welded back on the Atlas jug and the top of the jug milled flat. I used a thick copper head gasket that I made at college if I recall correctly.
The best crank I had was the Atlas and I seem to recall it was a bit heavier and the balance was slightly different. I had a lot of rods and pistons and spent quite a while balancing and polishing up the best set I matched up. I had far more time than money.
A local machine shop dynamic balanced the assembly for me.
By then I realized that I could not afford to race and aimed for reliability (that engine ran nearly every day for several years after a cross country trip).
If I recall it was not as easy to spin up (heavier crank and lower compression) as a Commando stock, but it ended up being smoother than my original and burning far less oil. That may also have been helped by the fact that it held a lot of oil. Oil was the only way I could cool it so I used as much capacity as I could including the frame.
This makes me think I could add an Atlas crank to this bike and make it smoother.
It just went on its first test ride, amusing my neighbors who waved cheerfully. They are a bit used to half assembled bikes coming out of my garage with no license plates and rumbling down the block. The little kids love my bikes.
The results are they she smooths out to be acceptable but still buzzy and is very easy to ride. It makes my Goldwings seem like trucks.
I was having my problems with shifting and brake on the other side but I'll learn to live with it I'm sure.
The lack of mirrors were a pain so I added bar ends when I returned.
The front brake is truly lame at the moment and will need to be looked at. The rear has a loose adjustment but takes OK.
The tranny does all the gears but the oil is way too heavy, probably somebody used 90 wt.
Clutch is OK, engine sounds great. I'd say that is a stock Commando cam by the sound, certainly not a hot one.
The engine case is a 72 I think and probably not my favorite type. It seems to have a tiny drain plug at the front and may be the type that could empty the sump at sustained high RPMs.
I'll be running mountain roads with this bike and you can barely get out of third gear on the way to Alice's restaurant, so I doubt I'll pump it dry. We actually had longer stretches to run with it up in Maine and it lived through that for years.
Do any of you experts know about the 72 style cases? Is there any help for them without a teardown?

The crankshaft balance factor can be altered to suit the featherbed frame?

Click to expand...

I believe Les means this as a statement and not a question. I think many Commando to Atlas transplants are done this way. As I recall Commandos are balanced to 52% while the Atlas is 84%. Many Commando/Featherbed builders suggest 77% for a rigid mount engine.

Simply changing cranks from Commando to Atlas has other problems. Most important is the drive side is different, requiring a change in the primary drive from Commando style to Atlas. Also, Commando rods and pistons are probably different weight than Atlas, so the balance factor would not be the same as stock Atlas.

It does seem to me that I used the Commando primary which I believe was triple row. I probably had to press off the sprocket from the Commando crank, but as I say this was years ago.
I'm pretty sure I would have done that because I recall breaking the Atlas type primary chain due to a lcak of self control.
It was a good thing that the gentleman who balanced the engine knew his stuff becuase although I knew I needed balancing I had no idea of factors.
It also seems I had pistons and rods from early Commandos and late Atlas models that were much the same. Of course one never knows what may have been fitted to the blown up engines I bought for parts.

I've been searching the board to learn a bit about the late case I have now. All I have to go by at the moment is stuff I have heard from other bikers who say my case would be a problem for sustained high speed.
As far as the wet sumping goes most bikes with a seperate sump do that and my remedy was just to warm up gently ride very easily for the first ten miles or so. It was never a problem if I rode the bike within a month.
Since I ran Greyhound busses NY to SF this problem only came up when we visited my wife's family in Kiwi.
Basically I've been out of the loop for many years and have a lot to catch up on.

If you have the '72-73 style "Combat" cases, you will have the breather at the rear of the crankcases rather than off the end of the camshaft. There is no real fix for the sump pickup without splitting the cases. You could relocate the breather but that is only a partial fix.

That being said, I have had my '73 with the same style cases for 35 years and have never run the oil tank dry due to starving the pick up or blowing it up the breather. This is probably due to riding style and luck. I see the potentlal for problems, and don't disagree that it happens though and when I have this style cases apart I have them machined and relocate the breather to the back of the timing cover with additional holes in the case to breathe though the timing side.

Thanks Don,

I'll look when I get home to see where the breather comes from. I'm pretty sure this engine was not a Combat as it feels like a normal Commando as far as kicking effort. The cam is not that lopey but it has been years since I saw a Combat. Heck, I rarely see a Commado.
I understand there was also a detuned one later?
You never know what someone put in it until you tear it down, I can see that the case has been sealed with bathtub silicone like I used to use.
It doesn't leak, even after sitting for months at a time.

Cookie said:

I've been searching the board to learn a bit about the late case I have now. All I have to go by at the moment is stuff I have heard from other bikers who say my case would be a problem for sustained high speed.

Click to expand...

There is a fairly simple modification that can be done to the '72 (and '73 750) cases which, as far as I know, cures the problem completely, but the cases do have to be split, as Ron L has mentioned: http://www.oldbritts.com/n_c_case.html




.

Thanks guys,

With this information I'll start out by trying to figure what I have now.
I'm not likely to tear down such a nice clean engine for race mods these days, but if I have it apart that is a mod I will do just in case.
Just in case..ha ha.

The breather on this bike is almost funny. It runs from the center of the plate where the magneto used to attach to the top of the oil tank with a largish hose. Then a line runs from the oil tank to the rear fender of the bike from the same high area of the tank toward the rear, and dumps directly out past the rear fender by the taillight.
One should not build up a lot of pressure here, and you have the James Bond like ability to oil pursuers simply by adding a bit too much oil to the tank I believe.
Does this mean I have the much undesired case?
I cleaned and de glazed the front brake today after soaking the frozen adjuster over night. This may give some of you the willies but I put the rusty adjuster in acid for an hour and then neutralized it with water. After that the old chuck in the vise to heat and free followed by antisieze on the adjusters.
After servicing the cable with lube and cleaning the brake light contacts with contact cleaner I reinstalled and it seems much better.