XJ650 Seca spark diagnosis coil?

Hi guys,
I need a bit of technical assistance.
bike is running a bit off. cylinders 3 and 4 are running cool @approx 85celcius. about 50 degrees celcius colder than cylinders 1 and 2 @140celcius. idle is bit all over the shop some time is ok and often if i rev it the idle hangs up, thought it was fuel issue, but after many hours and several dollars i have now been through the carbs with fine tooth comb and sorted any air leaks from intakes...

I have checked spark and they seem weak. not strong and fat and blue, more thin and orangey.

I want to check the coils but i cant for the life of me work out where i probe with the multi meter.
I know Im looking for approx 650 ohms. But I dont know where exactly..
The only resistance I have found is if I probe the 2 input wires on each coil (coloured, red with white strip and orange. or red with white stripe and grey.) when I do that i get aprox 3 ohms on both coils. otherwise everything I probe against such as the metal earth point and the spark plug cap and any combination I get open circuit.

I suspect I am doing something wrong???
also
I have not removed the coils from the frame, is this necessary to perform the check??
Any guidance greatly appreciated
Thanks.

 

Ok.
So I found how to check the coils in another thread. http://www.xjbikes.com/forums/threads/just-another-help-thread.118464/#post-593656
Thanks XJ550h!!!

so for mine:
coil for 1 and 4 was primary 2.6 secondary 11.something Mega ohms and jumped all over the place.
coil for 2and 3 was primary 2.5 and 21.66kohms constant
this is with plug caps on.
so it looks like Ive got a bad coil.

though this doesn't explain why it is cylinder 3 and 4 that is running cool??
Any thoughts???

Im thinking of buying these ebay coils https://www.ebay.com.au/itm/Whites-...072453&hash=item4d6df4b223:g:alIAAOSwFIVauISw
is there any risk running these higher resistance coils?
specs:

• Voltage: 12V
• Primary: 2.76 Ohm
• Secondary: 18.30k Ohm
• Holes Centres: 90mm
• Leads: Twin
• Suits: Cd
  

 

You need to check them with the caps off after determining they are out of spec with the caps on. It could just be a bad plug cap or poor connection. Unscrew the caps and check the coil by itself, then check the caps. If they are both OK individually then likely a poor / corroded connection. You can trim a bit of the plug wire end to restore the connection, and some plug caps can be disassembled and cleaned to restore back to spec.

Here's a good read on dyna coils if you decide to replace and upgrade.

http://www.xjbikes.com/forums/threads/yes-dynatek-coils-make-a-difference.117797/#post-589572

Not sure about the different heating. What method did you use to check the temperature? How long had it been running and where was it measured? You have to be careful with the IR guns on reflective surfaces as they will display an inaccurate reading.

 

that sounds right

take them off and go right into the wire

try new plugs
750 honda coils are supposed to work well

 

Yes the Honda CB750 coils have worked. I picked up these
https://www.amazon.com/gp/product/B01MYA7ES1/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

I bought different caps that were the proper resistance as I don’t believe the ones included were.

There are other members who have also recommended CB750 coils. Not sure what brand/suppliers they’ve used.

 

Thanks for the replies!
Yeah just did test with caps off. Still way out. Caps are new.

Taylo105 Those coils look fine but they don't ship to Australia.

Does anyone know if the higher resistance rated coil is an issue? They r advertised as suited to the xj650.

Also this still doesn't explain why cylinders and 3 and 4 are cooler.. I have tested and retested being mindful of reflective surfaces, yet still consistently cooler on 3and 4.
Bad coil could explain the poor running esp. At idle and poor start. But when it is under load and higher rpm it runs perfect.

 

Where do you get the dynatek coils from? Are there any specs for them?

 

https://www.z1enterprises.com/dyna-dual-output-30-ohm-coils-pair-dc1-1.html
that's what they look like, DC1-1 coils.
you can look here but there are no tech specs that i found
http://www.dynaonline.com/default.aspx
3 ohms is the important part. more (5 ohms) might work and be safe, 3 is best, less than 3 draws too many amps for the TCI to work very long
the secondary number just needs to be close, +/- a few 1000
the mounting holes on these are 90 deg off so you need a bracket

revisit the mixture screws
i believe chacal has coils

 

Thanks I'll look into it

 

Quick update.
Still waiting on coils.
However I get enough spark to start and run.
So I had a fiddle with carb balance screws and idle mix screws and hey presto (Or more like 2 hours later) I've got the bike idling again.
It's been ten years since it idled near to properly. It isnt quite perfect but remarkabley better. Its So much better to ride, rolling off idle is smooth. So next step is get some vaccume gauges and try get it spot on...

Only problem now is I notice quite alot of clicking and clacking tapping sounds at idle particularly when warm.
It's been so long since I've had a decent idle I've forgotten what it sounded like...
I do remember it being noisey. I changed the cam chain and adjusted shims back 10 years ago or more( roughly 20000ks ago) And from memory the noise was much the same... Does any one else notice the tappety knockety sound espescialy when the engine is warmed up on their bikes???

 

tappety sound from valves is good thats how it is supposed to sound

 

Checking Factory Coils:

For all XJ models except XJ700, XJ750-X, and XJ900 models:

Primary (input from TCI): 2.5 ohms +/- 10%
= 2.25 ohms - 2.75 ohms acceptable range

Secondary (output to spark plugs): 11K ohms +/- 20%
= 8,800 ohms - 13,200 ohms acceptable range



Those aftermarket Honda coils have the following specs:

Specs:
2.42 ohms +/- 12% = 2.13 - 2.71 ohms
11.5 -12k ohms secondary

We had ordered a couple of sets to test them out, ohm-ed them, and they all ended up on the lower side of their specified primary ohm range.......some as low as almost 2.0 ohms. As Pollock noted, a lower-than-stock primary resistance will draw more power thru the TCI, and then the TCI electronics get overworked/over-heated, and the TCI dies an early death..... :-(

So it's a toss-up whether you'll receive a "good" set with enough primary resistance to be acceptable to use in the Yamaha systems. They may be fine for Honda models, which had an ignition system that was designed to be used with lower-ohm coils.

 

Thanks guys. Yeah I'm looking at getting some after market bolt on replacement coils. Tried a set of high performance but the fitment was going to be an issue. Mainly didn't like the idea of them being so different from the stock look...
These are the ones I'm likely to get now https://m.ebay.com.au/itm/SET-OF-2-...rentrq:af7ee6cb1620abc2f6fbee64fff9d5d1|iid:1

 

Xj550h
Thanks.
So it's quite normal all that chattering? It seems quite loud when warm, was almost worried there was a bit of rod knock...