72 T500 intermittent spark issue

[leleva]

So I bought this bike a couple years ago and have slowly been trying to get it running. When I bought it I was told it ran a few years ago but sounded funny. So went threw and rebuilt the carbs, found the baffles for it, and noticed the Right cylinder didn't have spark ll the time and it was rather weak. So I changed points and condensers. Tested the coils. still no luck. Check the magneto test fine. eventual went threw and cleaned the 3 grounds on the bike. This gave it a little bit more spark as it seemed. I eventually found out it wasn't grounding out at the coil. So I cleaned the coil Bar things up and It gave me amazing blue spark. Now here is the issue IT gives the amazing spark, every time its suppose to when I kick it over. When I try to start it, it will fire a few times then drop all spark on that cylinder. The bike runs on the left cylinder ( very well I might add), So I tried hooking up my inductive timing light and It registers not spark on that cylinder ( originally thought the timing was way off on that cylinder). So I traced down the orange power wire to the junction and it seems fine. I'm kind of at a loss with this bike. The only thing I can think of is my brand new points are sticking? I know it has to be some thing simple as it only affect the right cylinder.

[jabcb]

Did you mean:
The left cylinder is always ok, gets good spark & runs fine?

The right cylinder has good spark when you manually operate the points?
Right cylinder has good spark only when the engine is turning over really slow via the kick starter?
Inductive timing light flashes for the right cylinder when the engine is turning over really slow via the kick starter?

When the engine starts running the right cylinder runs briefly but then will not cause the inductive timing light to flash?

-------
This could be because the right coil is going bad.

To test this, you can run temporary wires so that the points connect to the other coils & switch the HT leads.
Then does the right cylinder run good & are the problems with the left cylinder?

[leleva]

I had both coils out and tested them manually by hooking up a mock ignition system and they both worked great. But what you said is true about what I was trying to say.

[jabcb]

The spark plug caps have resistors in them. These resistors can also go bad.

Did you check the coil primary & secondary resistances?
Did you check for grounds (resistance between one of the primary connections & the coil metal core)?

[leleva]

hmm, didn't know that they had resistors in the caps, and I did check resistance but that was probably a year ago. So I'll check that tomorrow, also some one mentioned I might need a battery to actually make the other cylinder fire.

[leleva]

So the only thing my meter registered was across the 2 terminals:

SO right cylinder at 4.5 ohms

and the left cylinder at 4 ohms flat


I take it the coil is on its way out?

[leleva]

So swapped the points wires on the coils and flipped the spark plug wires. Still wouldn't fire on the right cylinder, so went farther back to the magneto to wiring harness to main wiring harness. still the same thing. So my true trouble is either the magneto, Points or condenser.

[jabcb]

Check the voltage at the points with the points open & closed.
Also make sure you installed the points correctly. You won't get a spark if the insulators are not as shown in the pic.

[leleva]

The points wiring to that picture where the same. However I ended up buying another magneto/ points plate. I can here both cylinders wanting to fire, but I realy have to get a good swing of that kick starter to hear any thing. out of the magneto. Could it be that my permanent magnets are going on now?

[tz375]

You mention Magneto and magnet strength and kicking it hard. That bike doesn't have a magneto. It has battery powered ignition with an alternator to keep the battery charged.

Are you trying to run it without a battery or with a dead battery by any chance?

[jabcb]

The T500 does not have a magneto. It has conventional battery-points ignition.

With a reasonably good charged battery, you should be able to get a spark by manually operating the points when the crank is stationary.

Am quite busy at the moment. Will get back to you with a more complete response when I can.

[leleva]

well, I guess I could probably get a battery and it woudl probably run. any recommendations for a decent battery then?

[jabcb]

If you are going to stick with the stock voltage regulator than you should get a cheap conventional battery that requires you to add water from time to time.

[leleva]

so I shouldn't go with a AGM, I had a conventional battery in my F7 but it flat lined the next spring.

[jabcb]

With the stock voltage regulator you can get up to something like 16V at high rpm -- that's too much for AGM batteries.