Dyna Mini coils?

I spoke to the DYNA Technician. Get the GREEN ones!

 

And Yamaha specs 3 ohm coils for our XJ's folks, not 2.5 ohm.
For Dyna's, the "GREEN ones" are the DC1-1 3 ohm coils. That's the ones pretty much everyone is using, and certainly the ones I'm planning on using.

 

Chacal,
Using the 3 ohm coil with 12 volts across it won't give a reduced output, because the full 12 volts is across the coil i.e. there is no resistor dropping the voltage. So you will get the full 40 kV.
Same thing if you used the 2.5 ohm coil with no resistor; you would get the full output.
The difference between these would be the current flowing through the primary of the coil, which is where you need to see what our bikes were meant to handle. And it sounds like they would like a 3 ohm coil.
Jim

 

Okay, I'll use the 3.0 coils.....just wanted to investigate, thank you everyone for your input. Altus, why/how/where did you determine that Yamaha specs the coils at 3.0 ohms. In the Yammy service manual and the Haynes manual under the coil testing section it says that the coils should be 2.5 ohms primary resistance +/- 10% (2.25 - 2.75)???

 

Well lookit that, I stand corrected. Will ya look at that - the service manual actually DOES say 2.5 ohm

I've always relied on the 3 ohm figure and it's what I've always been told - probably because no one makes a 2.5 ohm coil, so the 3's are the closest fit.

 

Go for the DC1-1's!

I installed the DC1-1's in my '85 Maxim-X 750. It's not as hard as it sounds. I can't find the website that helped me through it right now...

Anyway, it's maybe 2-3 hours start to finish. No real setbacks. All you need is the DC1-1 coils, a small length of brass / stainless steel rod, and a cotter pin that you can punch through the rod. New ignition wires to go with the new coils are nice since the old wires are pretty much attached to the old coils permanently. I used Dyna wires.

- Take out the old coils and the bracket that holds them.
- Mount the front (headlight) of the coils to the bracket as usual. This causes the back of the coils to slant away from each other, preventing them from mounting where they should, thus causing them to hang down towards the engine.
- Bend a small length of the rod into a U. The top of the U goes into the mounting bracket, the bottom half loops through both coils. This holds the coils up, preventing them from bouncing on the engine. There's enough tension on the front of the mount to stop any horizontal movement and this bracket stops any vertical movement.
- Put the cotter pin through the rod so it doesn't slide out.
- Connect your ignition wires.

Does this make any sense? I'm Google impaired right now, but there is another guy who has pics that illustrate what I say.

It's really not any harder than what else you're suggesting with resistor mods.

Corey

 

hi all

now im in the same boat as every one else it seems i need a coil.for my 80 mod 650 max what is the best cheapest coil ?

thanks john

 

The free one your Uncle Joe has laying on a back shelf in his shop!
Had to pull your leg mate, that one was too good to pass up.
Seriously, you've a few options. Dyna is a good coil and I've had no trouble with my Accels. I am not aware of the price of the Dynas but I paid $125 USD for the Accels some 13 years ago, not sure what it would run this day in age.

 

I know Hap's website has information on installation here: Maximum Maxim X

I plan on doing this too, once winter truly sets in and I can't ride anymore.

 

Actually, I may be able to hold off for a while. I tested my coil resistance today and the wires 1&4 produced 12.16 and wires 2&3 produced 12.29.

I'll still upgrade sometime in the future, but at least I cna put it off for a while.

 

That's the one!

Good instructions, but I do think that he's making it slightly harder than it needs to be. I didn't use the brake line to hold the coils apart and I don't see any horizontal force that would make them smack together. I also didn't need the extra bends in the rod. I just made a perfect U and it keeps the coils raised and happy. I couldn't find stainless steel rod, but Home Depot had brass in stock and I think it will be fine.

Corey

 

I've seen his bike. (Nice ride, btw... pretty color). He is a real source of information when it comes to the Maxim X and I have relied on him many times. He's supposed to be re-doing the page; maybe he'll take that part out. I figure if he says it needs to be there, he's been doing this a lot longer than me, so eventually when I change mine, I'll do it like he did his.

I tested my coils first, which were within spec at 3.2ohms. I've been trying to track down a hard start problem. Then on to the plugs. I tested all of them first, found one at 32.0kohms, and one at 18.2kohm. Well outside operating specs. I went and bought 4 new ones, and so far, the bike is still running. I also received my CarbTune II today and colortune plug. Yay! I posted a bunch of pics on my blogsite. Check it out.

My Blog!

 

>I tested my coils first, which were within spec at 3.2ohms.
That doesn't mean anything, the HV winding can be bad with a shorted winding or short to ground or the case can be cracked, which is pretty common. You need to test the output voltage on a scope or at least use a spark tester to see if it makes a decent spark that's strong enough to fire a plug.
In my experience hard starting is caused by a weak spark due to bad coils and a lean mixture if it's cold out. With the colortune you can check the mixture at idle but most people forget about the starting jets that can be clogged and you can't really check them except to see if they make the mixture richer and the hole in the jet is completely open like it should be.

 

Dang it! I just started grasping the concept of the multimeter and now you're telling me I need a scope or another kind of spark tester? Yikes!

Sounds like you really know what you're talking about. You've had trouble with hard starting too? If so, I'd like to hear what you did to rectify it.
I know a few of the spark plug caps were bad; having a resistance of 32.0 is a good indicator that spark wasn't getting through, right? I haven't yet tried it this morning, but that's going to be one of the first things I do. I'm excited and scared at the same time. I hadn't thought about the starter jets... seafoam has been run through this bike for the past 2 weeks, added some with every gas fill up (just about).

I'll look into other spark testers. Thanks for the info!

 

MadMaxim, the reason you can't count on your multimeter to do a complete diagnosis of the High Voltage side of the ignition system is the multimeter uses voltages 1/10,000th or so of what is generated for the spark.

You can think of the high voltage side of the ignition like a water hose. In your garden hose your goal is to get water in one end and out the other. Things that can prevent getting the water to the other end are:

1) restrictions (kinks)
2) leaks

Imagine testing your garden hose with just a trickle of water. There may not be enough pressure to have any noticible amount of water lost to leaks. Also, the kinks in the hose may not be severe enough to noticibly prevent the water from flowing.

Now imagine turning the spigot on full blast. The kinks reduce the water flowing through the hose and the leaks let water out all over the place, reducing the pressure.

At the end of the day, the only way to know if your hose is in good shape is to look at the outlet when the water is on full pressure.

This is what ArizonaSteve is telling you how to do with the ignition system.

It is not unusal for the high voltage side of ignition systems to have "leaks". The insulators in the system can degrade. They will hold the 2 volts from your meter in fine but will drain that 25,000 volt spark right away, leaving just a trickle or nothing for your spark plug.

SIDE NOTE:
Dad used to check the high voltage side of his car ignition systems by looking at the engine running in the dark. Many of the leaks glow like little blue lights. An internal problem with a coil cannot usually be seen this way, but a great way to check out the wires and plug caps.

 

Yep, you can still check the ignition system in the dark.
I cured any hard starting problems by putting on Accel coils. A lot of owners report not being able to start if the battery is slightly weak but I get a good spark and can start just fine even with a weak battery as long as it's got enough power to turn the starter.

 

Elp u lot out a little.

1st , a resistor does indeed reduce the current THEN the effect of that drops the voltage. mr Ohms law , look it up , there are free little progamms out there to play with.

2nd,the main reason it might not be healthy to use a 1.5 ohm coil instead of a 3 ohm coil is only due to the TCI transistors that switch the current on AND off might not be able to handle the extra current when lowering the resistance using 1.5 ohm coils , BUT if the TCI transistors could handle it the spark will shurly be increased in strength compared side by side.

In other words the yama TCI design factor.

Lower resistance = more current AND a higher voltage as when the field [12v coil side] collapses with a few extra volts on it the few extra are transfered to the secondary coil [HV] by the turns ratio of them.

Quoted differences of eg:12,000 ohms =12k ohms , from 12.5k or even 13k is a negaligable difference and effect at those resistances and voltages [40k volts] , in other words , a bee's dick difference.

Differences at low volts [12v] with resistance ie 2 ohm compared to 10 ohm depending on whats doin what can be dramatik.

hope that elps a little.

 

Play here http://www.csgnetwork.com/ohmslaw.html

 

Once again: Bosch Car Coils from any Car that has electronic ignition .
That would be about '76, But Go for '80 onwards (just for insurance) Almost FREE at a wreckers (these are almost indestructible things) they have 3 ohm primaries making them exactly compatible with Yama units but with a 45,000 volt output. .
In truth they are largish ugly things.. but.. they will do their job better than most any others you can buy... for Lots less $$

 

Chacal far from me to outsmart you when it comes to XJ's but on yamaha service manual for XJ700 N/NC it states the coils should be 2.7ohm + or - 10% at 68F/ 20C it is on page 6-28 of the above mentioned manual. So that being said 3 ohm sounds within spec for the mini dynatek coils plus there are several guys here using them and even saying that some anomalies like erratic idle and hard to start ae all gone now.