Good Running 1982 XJ750J, suddenly Won't start

This was posted in another thread but moved to a new post per request of "KMoe"

1)I have a 1982 XH759J that just all of a sudden won't start. Plugs have spark ( checked all four). and has fuel in tank.

2) How do I check / correct the firing order?

3) When I have it jumper cable connected to my truck it sounds like starter is clicking and trying to turn over, but only occasionally back fires ( loudly).

Also has new air filter, new turn signals, and new tires. Only change was that it fell over the night before ( cranked and ran after being on it's side though).

 

How long was it down?
Check the crankcase for gas.

 

Down for only a few minutes ( up to 5 minutes according to witness).... Long story, just say I was not happy.

 

How do I check Crank case for gas ( other than change oil)? , and it fired right up after being on it's side ( three times, different trips ) then went out in morning and no start.

 

Open up the oil filler cap and smell. If you smell gas, that's bad. Also, how much oil in the case can tell you, if it's fuller than when you last checked, chances are high that it's gas.

 

When you thumb the starter, does the starter spin as strongly as it did before the spill?

Have you checked to make sure the sidestand switch isn't sticky?

 

As far as I can tell Starter spins same ( not really. Sure I was not noting it before.

How Do I check side stand switch ( and should it matter , with bike in Nuetrual).

 

pull the sidestand safety relay. to test sidestand switch.

starter clicking or solenoid clicking?

gas in oil check oil level bike up on centerstand look into the oil sight glass on clutch cover this will show if your oil level is too high due to gas in oil.

and your question about jump starting bike with car running your not even supposed to jump another car with car running. you could blow out your voltage regulator or battery because of the high amperage of a car alternator

an 1100 has a 35 amp alternator where a car has a 65 amp alternator

 

Firstly, don't get too fixated that it is related to the bike having fallen over, but do check the pickup coil on the end of the crank shaft for damage. Also consider the possibility of garbage shifting from the right side of the tank to the fuel tap side and then finding its way to the carbs. If, after cranking it for a minute or so, sniff the exhaust pipe for the smell of fuel. That will tell you fuel is getting through.
You have done a bit of work on the electricals, might have disturbed a connector. Recheck all the connectors relating to the ignition system, ignitor block, pickup coil from crank shaft end and ignition coil pack. Finally, check some prankster hasn't swapped a pair of plug leads,
Hope this helps.

 

coil pack on left goes to cylinder 1 and 4 . coil pack on right goes to cylinder 2 and 3. go from left to right .

 

Then label wires with silver sharpie for easy reference in the future (if the original labels are gone).

 

Any luck yet? Given the loud back firing lets go with the idea fuel is getting in and you are getting a spark. Might as well pull all the plugs and turn the motor over to confirm you are getting compression in each cylinder and also whether flooded. If any gas mist comes flying out you're flooded bad and should keep turning it over some more to clear as much as possible -wet plugs are a sure sign as well -dry those suckers off. Once dry as possible re-install plugs and plug wires and turn over bike with choke off and see what you get. Full throttle can help clear a flooded bike as well while you are turning it over. If after that you don't get any action then slowly add choke and see how things go.

 

Update: Might have bad battery ( according to Father-in-law who sells for Deka Battery , after looking at the battery) .

Also found the smell of gas in the Crank case oil... So what does that mean?

Plan on getting a new battery and maybe new plugs ( just to be sure). Will see if that helps any.

 

Gas in the oil means that gas got into the oil when the bike was on its side. You need to change the oil, and oil filter, before you try to start the engine again.
With enough gas in the crankcase she'll be difficult to start. This is a good thing, because with enough gas in the crankcase you can end up bending a connecting rod (or making a loud KABOOM!!) should the engine manage to start. If you let the engine run with gas-diluted oil, you'll shorly have damaged bearings.

You'll also want to use a length of clear hose to check that the float needles haven't gotten stuck, and are still regulating fuel flow. Put the hose on the float drains, and use it to check the fuel level against the side of the float bowls.

Your battery is probably fine, but should be load-tested anyway.

 

Battery was tested ( By AutoZone) and said Battery was at 90% ( Salesman said that means it is good) but needed to be charged ( and was at Fire Station).

Took a spark plug to local Yamaha dealer. Worker said plug looked good, but bike was running very Lean. So what would make it run very Lean? I took tank off and made sure fuel filter was cleaned and fuel flowing through it.

Also changed the oil ( and filter) since I thought I smelled fuel in the Crank case ( oil).

Assuming the bike still won't start what is next, also assuming that it is running "Lean" ( it has stock air filter , tank and other fuel parts as far as I can tell).

 

@Geriatrix mentioned checking all electrical connections. That is a good thought regardless, clean, die-electric grease and tighten.

A lean condition means you have too much air or not enough fuel. Have the carbs ever been rebuilt? When the bike tipped was it a jarring drop or a slow slip?

 

lean all plugs look the same?
where did you set mixture screws to?
oem air filter or aftermarket?

 

All plugs look same ( almost all white). No clue as to mixture screw setting ( where is it?). Fresh OEM in bike.

 

mixture screw is on front top of carbs may be under a little plug
if you look at the second photo in this thread you will see the mixture screw in the resessed hole to the right of the enrichment plunger .put on your shades before viewing
OWWW, My Eyes!

 

After a quick chat with local Yamaha dealer ( by phone). I checked all four plug wires ( had only checked. two earlier) and found two plug wires had no spark ( plugs we're good, just not getting energy). So believe it to be Ignition Coil (or plug wires) to the #2/#3 cylinders that is bad....
Now I tried to find new Ignition Coil and seem to be hitting dead ends. Anybody know a good cheap source for said part ( link to suggested site help more then then saying "go here").

 

Before looking for replacement parts, test the parts you have.

Start by unscrewing the plug caps from the plug wires, and cutting the wires back about 1/8 of an inch to remove any corrosion. Screw the caps back on and check for spark (making sure that all plugs are grounded to the head).

If you still have a loss of spark, proceed to testing plug cap and coil resistances.

Plug caps should be 5k Ohm.

Primary (small wire) side of the coils should be 3 Ohm.

Secondary (big wire) side of the coils should be 11k Ohm.

If you choose to measure the secondary side of the coils with the plug caps on, you should see 21k Ohm.

If that checks out, you are looking at a wiring issue, not a parts issue.

 

honda cb750 coils have been used do a search on this site
Cycle Recycle part 2 has them for like 39$ each and they carry the wire and caps too. get 2 0f them or buy used yamaha ones on ebay

http://www.newmotorcycleparts.net/electrical/coils.html

 

Update: Been busy with other parts of life. Local Yamaha dealer said the coil to 1/4 was bad , but before I removed both coils the 2/3 was not sparking ( but 1/4 coil was) ... any idea in what is going on? ( thinking that of just replacing both to be safe, but I hat us expensive).

 

bikes are expensive

TECH TOPIC: The Real Costs of Maintenance

 

How reliable are "after market" coils? Are they a smart option, or is it an OEM only thing?

 

cost wise the aftermarket is best buy and you can change the sparkplug wires.

the cb750 coils are a good price

 

Any important "Specs" I need to pay attention to?

 

Does the XJ750 have an inductive type ignition, or a CDI ignition?

 

The Honda CB750 coils can be bought new and have replaceable plug wires. These coils are Hitachi coils so they mount like stock ...I have ran them 2 seasons with no issues . My old coils were cracked and I had these coils in my part stach from when I had a CB750 . One thing about the battery laying on it's side for even a few minutes on an unsealed battery have you checked the electolyte level ...if it is low service with distilled water only.Have you checked all the fuses?

 

TCI.

 

K-moe is correct it's a tci controller with capacitive discharge coils. Test everything. I just went through this same issue and found that my plug caps were the issue and they're relatively cheap to replace. I spent 30 bucks on 4 caps and 4 plugs vs 150 for a coil kit.

 

I have an AGM Sealed battery ( also had it checked and confirmed .. twice).
Fuses were checked... I am currently at the point of the checks of : Ignition coil that failed the test.

 

Update: I managed to find a very highly rated Ebay seller who had used (but tested good) 82-83 XJ750 ignition coils and waiting for them to arrive.

 

Update: Installed the new to me used Ignition coil, still won't start. Took it to a Yamaha dealer who said the issue was electrical between Battery ( said was working) and Ignition coils ( Said they both passed the Ohm primary/secondary tests. so the issue is either at the starting coils ( Bike repair man's words)) or something else.

I am mechanically inclined, but am very new to the sport of "Wrenching" as I did not have a good "teacher" growing up and am worried about doing more damage then good without another set of eyes on my work as I learn.

Wife said I either sell this bike and buy a newer bike that local dealerships can fix, or get this one running soon.

 

can you put a volt meter on the battery so you can see the current at rest, and then while it is still connected, turn the key on, make sure the right hand switch is set to "RUN". Now, press the start button and let us know what the voltage drops to.

Dave

 

Have you done THIS yet?

 

ohm out your pickup coils it is the other connector to the tci, gray wire to black wire and orange wire to black wire also all 3 wires to ground.
dealership should have done this.

The Ultimate Relay, Switch, Sensor, and Diodes Guide

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range

 

Yes

 

And the results were-------

 

A little over 12 volt before connected, will record the numbers again. ( wrote them down before changing ignition coil, but will redo test. But this sounds like a battery check.)
what do you mean by the " Right hand switch" I am guessing your talking about the engine kill switch near top of right handle bar.

 

yes he wants you to do a voltage drop test

also test pick up coils ohm them out that is what the dealer was refering to and should have tested them

 

One set of wires sparks and other does not ( repeated by local Yamaha dealer mechanic) and that was why they said they tested ignition coils an found them to both pass the Ohm test. and suspected the pickup coils (or so I am guessing it is correctly called).

Worst pat is that my multi meter that I got ( new from my dad) seems to correctly read volts , but Ohm seems off (won't zero when tips are touched together as Manuel said) so I won't trust the Ohm reading from that meter (and reason I am not able to test Ohm's , just yet).

As for dealership, I am not sure if they checked that. did not seem they had any clue on how to work on this 35yr old bike. And other dealership in area said they won't even touch anything older then 10 years old ( 2007).

 

most dealerships do not know how to work on xj's unless the mechanic is 57 years old or older.
buy a new meter can be had cheap at wall mart or other stores.

i set of ignition coils firing is an indicator of bad pickup coils. or bad connections from tci to coils

bad spark plug caps corroded end of spark plug wires would just make 1 spark plug fail to spark unless both wires and caps were bad.

if your meter is bad or you suspect the ohms test does not workyou can not test the ignition system. find a new meter to use

 

Mine had one set not firing everything checked out on the coils. I checked the caps and they were out of spec. I bought new caps and that fixed it. Now it starts and runs. Try that.

 

what do you get when you touch probes together?

 

Is the meter you have analog or digital? If it's analog, look for a zeroing knob or wheel. Use that to zero the meter.

If it's digital, use a few resistors of a known value and see what the meter reads it as. Use that info to generate a correction factor (ex. if you consistently get a reading 500 ohms over the resistor value, subtract 500 ohms fom the meter reading).

 

That'd be my next thing to check. Even though you suspect your meter is off, you can at least see if they read consistently. One is definitely working so if they test the same they should be good.As 550h mentioned, only one set sparking is indicative of a faulty coil, faulty pickup coil, or TCI (least likely but it does happen.. The pickup coils are pretty easy to ohm out. If that's good, check your wiring and connections and finally replace the suspect TCI or send yours to someone on here to test. If you need some help and have cell service at the bike, I'll walk you through it if needed.

Do you have 12 volts at both coils with the ignition on? The TCI "switches" the ground side so you should see 12 volts at the coils (hook the negative meter lead to the battery neg or known good ground).

 

Wiring should you need colors etc.

 

Yes, on the right hand control, make sure you have the lever to "RUN", not "OFF". You wouldn't believe the number of times that someone has forgotten to set that to "RUN"

 

Here are the "Findings" from my tests today with my current Multi meter (I don't 100% trust it).

Battery: In volts
Before installing in bike: 12.73
Installed and key turned on : 12.06
Starter button ( and starter engaged): 10.8
Key turned off: 12.49

TCI plug to Ignition coil : In Ohms and wire color combinations.
Orange/Red : 3.0
Grey/Black: 4.0
Black/Red: 1.5
Grey/ Orange: 5.5

TCI plug to Ignition coil : In Volts and wire color combinations.
Orange/Red: 0
Grey/Black: 8.5

Second battery test:
Key off: 12.22
Key on: 9.5

Plug wires key on and starter engaged in Volts:
#1 : 1
#2: 0
#3: .05
#4: 10

I tried to test the larger (6 pin with 4 in use) plug/adapter at the TCI but found the results to be either no reading or faulty so I did record them.

Adapter/plug at the TCI for 4 pin one ( told was Ignition coils) are Blsack, Grey, Red/White strip, Orange.
Adapter/plug at TCI for 6 pin ( only 4 in use) one (Was told went to Pick=up coils) Black/Whit strip, Grey, Black/White strip, Orange.
Will post pictures of what I tested if you need them for reference.