81 sx650 open ignition coil

[ckahleer]

I'm getting an open reading from one plug wire to the other. I pulled the plug caps off and still reads open. I would like to pull the ignition wires out of the coil to test just the coil secondary. Can this be done or are they not removable? The plug caps read 10kohm each. is this correct? The bike runs, but poorly. rough idle and breaks up above 50mph.

 

[Jan_P]

What ignition system ?
5 k on one cap is what I have heard
Open seems wrong.. expect not running at all

 

[5twins]

No, you can't remove the plug wires from a stock coil. 10K ohms is high on the caps. I think their normal reading is 8 to 9K ohms. I'd replace them with 5K ohm NGKs, cheap and pretty much the standard of the industry. Many of us also replace the stock coil. We use the common Honda MP08 coil, cheap, readily available, and very reliable. It also has the benefit of allowing you to change the plug wires. Here's details on my install .....

https://www.xs650.com/threads/honda-mp08-coil.55408/

 

[ckahleer]

Its a stock. eletronic ignition.

 

[ckahleer]

Do I get a used 30+ year old Japan MP08 coil or a brand new knockoff Chinese coil?

 

[5twins]

I get the used ones. They're built like tanks, lol. The ones me and my buddies have been using have been working fine for several years now. I trust them more than Chinese ones.

 

[ckahleer]

Thanks 5twins. I just ordered a used set of coils on E-bay that came off a 1996 CB750 Nighthawk with 22k miles. So at least I'm getting coils that are 15 years newer than my bike, and I'll have a spare.

 

[ckahleer]

The Honda MP08 didn't help. Still misfiring above 50mph and hard acceleration.
Things done so far:
Dissasembled carburetors and cleaned passages.
Set float height
Ran bike with fuel bottle connected directly to carbs.
Replaced coil, plug wires, plug caps, and spark plugs.
Checked pickup coils resistance. They were within spec.
Went through Haynes manual troubleshooting flow chart. I'm down to the last item in the flow chart. Replace TCI unit.
I found these two old threads, and will try to repair my TCI unit or replace it with a Suzuki unit.

https://www.xs650.com/threads/tci-box-a-successful-repair-electronic-ignition-ignitor.3289/
https://www.xs650.com/threads/gonzo-diy-tci-system.57694/

What is the quickest way to remove The TCI unit. If I remove the battery box, will it come out with it. Or can I get it out another way.

 

[LeftyKash]

You can remove the TCI without taking the battery box off. It's attached to the underside of the battery box with a couple of bolts. It might be helpful to relive the regulator/rectifier or the little storage compartment on the right hand side to get to it.

For what it's worth, I had a bad TCI last year that I replaced with a used TCI off eBay. Last month the eBay TCI started acting up, so I did the gonzo switch (Suzuki unit). The bike was noticably more steady.

 

[ckahleer]

I checked the 4 diods in the TCI box and they are good. I will try replacing the power transistor If I can figure out how to order.
I can see letters and numbers ON6 ETD41-035