Coil test how to????

[xsleo1975]

Hi guys after hours of rewiring my bike(73 tx650)every thing checks out but the bike won't start, I went over and over all my connections and everything seems to be in order.
When I try to start the bike it looks like its not getting a good spark, this got me thinking it may by my coils.
Any help or sugestions are greatlly apriciated
Thanx Leonardo.

 

[XSLeo]

Unplug the two small wires on the coil. Test the ohms between these wires. This is the primary side. It should be about 3.9 ohms + or - 10%.
On the Secondary side measure from the plug wire to the orange wire, Should be 8k ohms, + or - 20%.
Dirty points can cause a weak spark. Get some heavy white paper, like business card are made from. Cut in 1/4 inch strips. Use electrical contact cleaner or alcohol to dampen the paper. Open the points, slip in paper, close points, pull out paper. Repeat till the paper come out clean.
Leo

 

[XSLeo]

Almost forgot, you need a good fully charged battery.
Leo

 

[xsleo1975]

Thanx Leo, I asumed all the components on the bike are original, worn out and expired the bike was running rough for like a mile or two then it will die and if I waited 20-30 mins some times if I was lucky the bike will start again.
About 3 weeks a go I went for a ride the longest so far with no problems until it was time to come home, and the bike wouldn't start at all, I killed my battery trying to get it running but nothing since then I recharge the battery with an automatic trickle charger but it looks like ill need a new battery as well.
Tomorrow I'm checking the coils with the method you sugested and ill decide if I need new parts
Do you think it's a good idea to replace the points,coil,cables etc. and star fresh ??
And again thanx for replaying, I was running out of options when I found you guys thank god!!!!
Thanx leo

 

[retiredgentleman]

Your old original ignition components are worn out giving you a very weak spark at best. Don't waste time testing, just throw them in the garbage.

Buy a new single coil with dual outputs. If you stay with points, the coil needs to be 4 to 5 ohms primary. Yes buy new points, and new spark plug leads.

If you want a better ignition, you should consider a Pamco with a new coil.

 

[xsleo1975]

Thanx retiredgentleman, I'm kind of new at this xs650 business this is my first bike and build so it has been a trial en error process, I hear a lot about the pamco system and I'm curious about it specially if the bike will run better, does mikes xs sales the dual output coil
Or where do I get it from?
Thanx I feel like making progress all ready

 

[retiredgentleman]

Don't be concerned about being new...............we were all new at one time.

You have to decide if you want to stay with points or go "high tech" with a Pamco. If you stay with points, you are restricted to 4 ohms or greater coils. That puts a limit on how strong a spark you will get. Points wear and need adjustments every so often.

If you go with a Pamco ignition, you can choose any coil from 2.5 ohm to 4.5 ohm primary resistance. That gives a much larger choice of coils. Some lads buy the Pamco with a coil as a set from Mikesxs. Some buy used coils off of E-bay, such as H-D coils, Honda coils, Andrews coils. I use an Accel coil that I bought new, and it has worked extremely well for me.. Prices for coils can be from $10.00 to $100.00+.

Pamco has recently brought out the E-advancer, which eliminates the ATU fly-weights and springs. With the points and the fly-weights gone, the engine starts and runs better and smoother.

I'm not a sales agent for Pamco or Accel, just stating what works well for me. Use the Google Search in the upper left corner to look around the site here. Choose what suits your budget.

The bottom line is that if you have old weak ignition, your engine will be hard to start and mostly run like crap.

 

[Purplezinger]

Early Yamaha coils were famous for being weak. The hot trick, back in the day, was to replace each of them with a Kmart brand coil for a Chevy pickup. I've used generic coils, nearly any 12v coil is better than a new original. The down side to this is size. Coils for a Chevy pickup are way bigger. You have to get creative with the mounting. Even today this is a good choice if you are staying with points. However, now we have more options and the Pamco ignition is the system of choice.

 

[wesleyonoel]

Might want to insure the charging system is doing what its supposed to. Always suspect on these motorcycles. Battery condition is also important. Make sure electrolyte level is where it should be and the battery is fully charged. Faulty battery and/or charging system can lead to the situation you describe. Once the battery discharges while riding, the ignition system will fail to function. Turn the key off for a period of time thereby allowing the battery time to recover (?) a bit and it might go - until the charge drops again. My suggestion would be to start with the battery and charging system. Granted the coils etc are old but doesn't necessarily make them junk. My '73 TX (16,000 miles) is still equipped with stock ignition components which funtion fine. Have fought with the charging system over a problem identical to that which you are experiencing. With a good battery and properly functioning charging system, you just might be in business again.............Wesley

 

[XSLeo]

New points are not to expensive. They are not very hard to set and adjust but can get time consuming. Your repair manual has the how to of changing and adjusting them.
I agree with RG on upgrading the coil. Even if you just upgrade to coil now If you get the right one you can still use it if and when you upgrade to a Pamco ignition.
I also agree with Wesley, you need a good battery to run the bike and get it to charge. Take your battery out of the bike, ensure it is full of water. If not then use DISTILLED water. Nothing else goes in your battery.
Once full of water, fully charge it. Take it to a battery seller and get it load tested.
If it tests ok then use it. If marginal or fails then get a new one.
There is a charging system trouble shooting guide around here some. I would link you to it but don't know how. You will find it in the XS650TECH section.
Most of the testing can be done with out the engine running.
Leo