[souperman]

OK here's my saga:

I installed a new Dynatek electronic ignition on my CB500T using a detailed PDF that is floating around. The bike ran great at first, both cylinders were strong. I put about 15 miles on it then it started hesitating badly off idle. I played around with the carb sync but the problem just got worse until the left cylinder went totally dead.

The timing on that cylinder is showing a severe amount of delay with the spark. While looking at it with a timing light it looks to be 45-50 degrees retarded, with an occasional blip at the correct mark. I tried swapping coils and plugs with no effect. While playing with the ignition timing plate the problem somehow migrated to the left cylinder, I cannot get it to go back no matter what I do. The advance weights are moving freely but not too loose.

Does anyone have any clue as to what's happening? The static timing of the bike looks fine, it only goes retarded when the engine is running.

Because it has happened with both carbs, coils, and spark plugs I think it has to be related to the ignition timing. I tried bypassing the kill switch also with no effect.

 

[Bird76Mojo]

Did you remove very much of the pickup itself? That could be an issue. No pinched wires? Re-checked ALL electrical connections?

GB :mrgreen:

 

[otr002]

:!:

 

[souperman]

Thanks for the feedback guys.

The problem started out on the pickup I removed material for the washer, but that cylinder is firing fine now as the problem is on the pickup I didn't have to modify now.

I checked the static timing with a multimeter and by watching the plug spark both. I checked the bob weights before and after it was all assembled by turning the bit on the cam by hand making sure it moved ok and snapped back. The plate is aligned with the pin on the cam shaft and is locked securely in place.

I was careful to be sure the bolt on the cam was not binding the rotor with the magnets in it.

The other cylinder does run ok and will sorta idle if I up the idle speed a bit to make up for dragging along the dead piston. When I flip the dead side's throttle it will backfire a bit thru the carb, and suck in pretty hard.

I've been through the wiring several times, under the assumption the issue would be between the pickups and where they plug into the coils. This is based on the fact that the problem stayed on the same cylinder when i swapped pickups at the coil and crossed plug wires to be sure the coils were ok.

Keep up the suggestions guys, I'm soo close to buying a new points assembly on ebay...

 

[Bird76Mojo]

If you stick with the Dyna unit you will figure it out. If all else fails one could switch back to the points just to see what happens but I'd stay the course with the Dyna.

Others here are far more knowledgeable on this than I am..

GB :mrgreen:

 

[otr002]

:!:

 

[souperman]

OK I'm by no means an electric ignition expert but I know a little about electronics. This is what I think might be happening. The hall sensors are pulling the voltage down from the coil wires from 12V to about 1V. When the magnet passes the sensor it "opens" and the voltage on that wire goes up to 12V, then gets pulled back down to 1V when it passes. It almost seems like the coil is being fired not when it goes up to 12V, but when it gets pulled back down to 1V. The position the cam is at when the magnet leaves the sensing area is very close the the retarded spark I'm seeing on the flywheel. I have no idea why it would be firing the coil as it went high to low rather then low to high though.

I'll double check the mechanical bits to be sure everything is tight tomorrow, including the screw clearance on the backside of the ignition plate.

This has me pretty frustrated, it is not really a complicated system. All the pieces seem to be functioning on their own.

Anyone got a spare set of points? The weather is turning nice and I NEED to ride!

 

[otr002]

:!:

 

[souperman]

Yes the condensers have been removed. I have timed the bike by first setting the left cylinder by rotating the plate, then locking it down. The right cylinder was timed by moving the sensor that has both of it's mounting screws accessible from the front side of the plate. Things line up nicely when the bike is cranked by hand. When I start the bike the right cylinder is seeing a nice fat spark, but according to the timing light it is happening way too late.

My rotor only has one magnet now, I reamed it out in a fit of frustration. I figured the bike only needed one since the other is just wasted spark at exhaust stroke. I do have to be careful now to put the rotor in the correct orientation so it is triggering on compression and not exhaust. The magnets were 180 degrees apart. But other then that nothing changed when I did it.

It is mechanically impossible to move the sensor so that the timing would be correct with the engine on, since one would have to overlap the other.

OK here is what I am seeing electrically. The black/white wire going to the coil is hot when the ignition and kill switch are on. The blue and yellow wires going to the coil are at slightly less then 1V at rest, and 12V when the hall effect sensor is tripped.

Does that sound normal?

Oh and don't worry about sounding condenscending, you have no idea how competent I am at this point

 

[otr002]

The primary windings of the coil need to have 12volt at all times this induces a magnetic field in the primary coil, this is feed by the ignition switch, when the power is switched off (hall sensor) the magnetic field of the primary coil collapses rapidly. The secondary coil is engulfed by a powerful magnetic field. This field induces a very high voltage current in the coils which is feed to the plug, boom :lol:

So, both coil feed wires must have 12 Volt (black/white on original coil), when the ignition is switched on OK thats checked!!

The red feed wires to the hall sensors also need to have 12 volts when the ignition is switched on, check this

Hall sensor is off with no magnetic field and on with one!

Black/white and blue/yellow will not have any current at rest

You have a timing issue and if you can static both cylinders then there is nothing wrong with the hall sensors
i know this does not help but i feel there is something wrong elseware

Rod from OZ

 

[66Sprint]

Just for fun, rotate the entire advance unit (or the center if you prefer) 180 degrees and re-time staticly....... The cylinders fire at 90 or 270 degrees apart on the camshaft, not at 180 apart..... Sounds like you may have timed it on the exhaust stroke to me.....

 

[otr002]

:!:

 

[66Sprint]

I wish someone had posted a good pic of the plate mods and mounted plate for reference.....It was the early 80's the last time I played with a Dyna..... Talk about headaches from trying to find a mental picture to discribe!.......I'm with ya!........But WHO is this "Great One" guy?....I only see a quote from me, NOT from him...(whoever HE is!)....... :roll: :lol:

 

[otr002]

:!:

 

[66Sprint]

That explains alot! .....Those look NOTHING like the Gold-Wing Dyna ignition I remember...... The one we used had smaller pick-up/trigger coils, and a larger diameter plastic carrier (with individual magnets) that replaced the advancer cam center....... (Still had to cut the clearance arc/notch for the eccentric adjuster's locknut, but there were no alterations to the pick-ups necessary)....Hmmmmmmm...... :? :?:

 

[souperman]

I'm not quite understanding what you mean here. The advance unit has a notch only on one side of it that fits the dowel pin in the camshaft one way. I can't see how it can be mounted wrong as long as the pin is in the slot so it won't spin on the cam shaft.

I have tried turning the lobe that is actuated by the advance weights 180 degrees, but the bike won't run at all that way.

On my bike the orientation is just like that first picture.

I was starting to wonder if it was possible for the cam chain to jump a tooth or two, but that should show a consistent offset when I static time which it does not. Electrically it all looks fine when it's not running. I'm having a hard time visualizing a mechanical issue that would throw off the timing of only one cylinder when it's running.

I have some points on their way, if anything maybe they will be able to help troubleshoot the issue and prove the Dynatek is OK.

Just for fun, rotate the entire advance unit (or the center if you prefer) 180 degrees and re-time staticly....... The cylinders fire at 90 or 270 degrees apart on the camshaft, not at 180 apart..... Sounds like you may have timed it on the exhaust stroke to me.....

 

[souperman]

Well I think I made some progress. The bike was running for a bit, but seems very flakey. If I try and bundle up the ignition wires up against the frame out of the way the bike starts acting up again. That points to a bad wire or short from what I can see.

What is interesting is that when the one cylinder is dead if I pull the plug cap and force it to arc to the plug that cylinder will pop to life. As soon as I plug it in solid and its touching the plug electrode the cylinder goes dead again.

The weird thing is that the issue still stays on the same cylinder when I swap the blue and yellow wires at the coils and the plug wires.

You guys think I should order a fresh set of coils,wires, and caps?

 

[Bird76Mojo]

What is interesting is that when the one cylinder is dead if I pull the plug cap and force it to arc to the plug that cylinder will pop to life. As soon as I plug it in solid and its touching the plug electrode the cylinder goes dead again.

The weird thing is that the issue still stays on the same cylinder when I swap the blue and yellow wires at the coils and the plug wires.

You guys think I should order a fresh set of coils,wires, and caps?

I'd try new parts and see what happens. Plugs first. Have you gapped the plugs properly?

GB :mrgreen: