Xj650 lack of spark or something else

Hi. I need a help with my bike. I have a xj650 4k0 11N model. I bought this as a non runner/misfire. I took carbs out and overhaul them. Put it on the bike and fired up on cylinder no 4 only. So I started investigation on what's the problem. I took ignition coils out on the table and measure them with multimeter and noticed they have pri resistance of 3.4Ohms and secondary resistance of 14Kohms instead of 2.5 and 11k. I've managed to fire the bike on 1St and 4th cylinder. Then I took the coils out again replaced Ht leads for silicone ones and new spark caps and when trying to fire this thing up it went bang through exhaust and didn't started. bike cranks but struggle to fire up. I've checked resistance on plugs the ignition coils are connected to and one show -5.4ohms and the other one doesn't show anything whichever way I check. I am planning to buy brand new ignition coils but I don't know if the tci is good. Can you advise me what should I checked next please. Also someone replace the fuse box and did a good job

 

http://xjbikes.com/forums/threads/how-to-ignition-troubleshooting.21932/

 

Swap the coils around so the #1/4 coil is hooked up to #2/4 and vice-versa. Does the problem follow the coil?

 

Did you say one coil is connected to #2 and#4?
If I misread that?
One coil to #1 &#4 the other to 2&3... I believe....
If I misunderstood excuse me.
You may wish to do a compression test and check the valve clearance , since it was bought as a non runner check everything .
Alan

 

Coil 1-4 works 2-3 doesn't. Compression shows 135 ish PSI on all 4 cylinders. When changing coils around bike doesn't start at all.

 

When you canged the coils around did you make sure that both the plug wires and the primary wires were switched to the correct cylinder pairs?

Since you know that 1&4 will fire you should have seen either;

2&3 fire when the coils were switched, but not 1&2 (bad #2/3 coil)

1&4 fire but not 2&3 (low or no voltage on the primary feed to 2&3)

Have you tried starting it in the dark to see if there are any blue sparkies jumping out of the plug wires? That could explain the whole problem (secondary voltage jumping to ground prior to reaching the spark plugs).

 

Mainly, you need to hook up the working coil (1/4), to the unknown (Grey) drive wires and see if you get spark. The bike won't run that way. It's just to check whether the TCI is correctly driving both coils.

 

Ignition Coils:
Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range
Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range
Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug
Pick-up coils:
1980-81 XJ650 Maxim and Midnight Maxim: 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982 XJ650RJ Seca (non-yics engines): 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982-84 XJ650 Maxim: 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982 XJ650RJC Seca (yics engine): 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982-83 XJ650 Turbo: 120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range

also make sure your battery is fully charged if it goes below 10 volts tci will not fire.

 

Swap so 1/4 is hooked up to 2/3
K-moe was up too late

 

Thanks for all your advice. Tomorrow I will try to change coils around

 

Hello again. I've tried today to start the bike and do all the test mentioned above but bike didn't started, now i think that tci is fried, and ignition coils are too strong so i will have to change them for as near as i can get to manufacturer spec. anyone has different ideas ?

 

Why do you think the " tci is fried" and what do you mean by " the coils are too strong"?

 

I've tested the TCI outcome ?
Battery Ignition OFF - 12.27 V
Battery Ignition On - 12 V
TCI red/white cable to red in multimeter black to black Ignition ON 11.5 V
TCI as above + cranking 7 V

Coils should be 2.5 Ohm pri resistance and secondary 11 KOhm
mine are 3.7 Ohm and 14 KOhm previous owner told me they are from kawasaki

 

You're chasing a ghost. 30 year old electricals need to be cleaned and sorted by process of elimination then reset to stock configuration (if possible).Once power through the harness is verified power into and through components will be much easier to troubleshoot. I'm going to shut up now.

Gary H.

 

Get the right coils to begin with.....

 

Local Yamaha guys told me that original coils are discontinued and their mechanic went through books to find out from what other model I can still buy them and they will be within parameters the original ones should be.
Price for 2 brand new coils was £160 that's about $240
I don't mind to spend that much money IF it will work.
I will order them and see what happens next.
I want to ask also If I will fit new coils and TCI will not going to work can anything else damage the coils in any way ?

 

if you think your tci is bad you could possibly ask here and someone may be w

correct coils needed
the 7 volts is a problem. under 10 volts and the tci will not fire.
try charging the battery or a new battery

 

+1. Have you tried member Chacal? He might be able to send you a good used set for less $.

Gary H.

 

I'll get new battery and coils and if this will not going to work I will change Tci and pickup coil. thanks for all your help

 

Will try him. I can get here (UK) used coils for about $76 BUT breakers don't give warranty on this and when I've asked them to check resistance on them they told me that they've been taken of running bike.

 

Update on situation. New battery fitted and still doesn't run. On the plug from tci red/white and black cables shows 7V when cranking. When I tool spark plug out and checked the spark it did appear, very weak and not in the rod but went inside the spark plug. Any ideas?

 

What is the voltage at the battery when your cranking it?

 

Be

better battery or boost from a good one,
7volts while cranking is low,
May need some contacts cleaned as well.

 

Use logical steps, always begin at the battery, then move forward

 

So you got 7 V on these wires… But what are you getting AT THE BATTERY TERMINALS When you crank the engine?

 

I will have a look on Friday what am I getting on the battery when cranking. Thanks for all your help

 

Ok update on situation folks. I've checked voltage when cranking on battery and it drops from 12.5 to 10V

 

just bring a meter with you and check them before you buy them

 

you need to charge the battery you are at the threshold of tci not firing because of low voltage

 

Hello everyone. I've manage to fire up the bike. on 2 cylinders and sometimes on 1 . I've checked voltage when cranking on the tci and it shows 7 V when engine is running it shows 14V at 2000 rpm . I've checked pickup coils and one shows 635 ohm and other 653 ohm and that is within 20% limit. When I've swooped ignition coils from 1-4 to 2-3 and then started the bike it run again on cylinder 1-4 so I suspect TCI is the problem but then I've stopped the engine and try to started it again and it did a big BANG from the exhaust.

 

Check the stator output voltage first. It may just be that the alternatior isn't making enough of the magic pixies.

the backfiring after switching the ignition off and then on is normal. It's a function of how the TCI manages the coils.

 

At 2000 rpm alternator gives about 13.3 volt. Above 2000 rpm goes upto 14

 

for your referance
tested my 550 tci is .37 volt lower than battery at standing voltage and drops to 7.8 volts when starting. battery at standing 11.86 drops to 10.75 tci standing 11.49 drops to7.8

 

Hi again. I've got the original ignition coils. Engine fired up, it run rough as hell but rouns on all 4 cylinders. Carbs have been rebuild but not set, and that's why it smoke I hope. I can't think that piston rings are crap because bike has 135psi on all 4 cylinders.

 

Could have leaking valve stem seals, or gas in the oil... but carbs needing cleaning and tuning is a more likely cause at this point. Glad to hear you got the ignition problem solved.

 

I would like to say Thank you to everyone that give me advice about my bike. Not sure if I cured it with different coils but it did work. I will test ride the bike tomorrow and let you all know with results. Carbs have been cleaned but not set. So I will buy kit to set the carbs. I will seek a thread here about it.

 

Ex

excellent , if the smoke clears up when the engine warms up I would suspect valve stem seals to be the reason , and IMHO isn't really anything to worry about , that bit of oil on start up is good for the rings and cylinders, and would only use a quart about every 4000-5000 miles

 

Hello again. I've fixed the spark problem. ignition coils was the issue. Replaced for second hand ones just to try if this is the case.

 

Thank you all for your help.