Author Topic: Questions on my new project bike.  (Read 320 times)

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Offline Wageslave

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Questions on my new project bike.
« on: December 02, 2019, 06:47:23 pm »
I just picked up an '86 ZG1000 off of Letgo and have started the process of getting it running again.  It supposedly has only sat for a year, but is kind of rough and refusing to start.  It came with no key, so I unplugged the ignition and jumpered the connectors to make it think it is in the run position.

It cranks over fine, but doesn't want to even start on ether.  It will stumble like it is trying but not enough to actually catch.  The carbs are full of crap and will be rebuilt, but it seems like spark is the bigger issue.  The coils fire during cranking, but the spark is weak on the 1 and 4 plugs.  Both coils measure about 24 ohms between the - and + connectors,  The left side coil measures full battery voltage at the - and + terminals, and you can see the trigger signal pulsing during cranking.  The right side coil measures about 1.5 volts, and also pulses during cranking.  Continuity checks good between the CDI box connector and the four terminals at the coils.

At this point, should I replace the CDI box or is there something else that I should be looking for to get fire?

Thanks

Offline m in sc

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Re: Questions on my new project bike.
« Reply #1 on: December 02, 2019, 08:12:18 pm »
it may be only sparking due to it being in start mode, when you let go of the starter it may not be continuing. id look for a key switch eventually, but id start with the carbs.
I break stuff. I fix stuff. (rinse & repeat as necessary)

Offline Brian

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Re: Questions on my new project bike.
« Reply #2 on: December 02, 2019, 08:23:57 pm »
Smarter people than I will be along shortly to add their thoughts, but I would sort out the fuel delivery issues first.  You mention you have some spark, but are you getting any fuel?
The Other Brian in Minnesota
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Offline Wageslave

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Re: Questions on my new project bike.
« Reply #3 on: December 02, 2019, 10:38:34 pm »
I have a full lock set in the mail, and a carb rebuild kit will be purchased soon.  The fuel inside of the gas tank looks like an orange smoothie, and the carbs are kind of rough.  I emptied the nasty gas out of the float bowls, and ran an external tank to feed the carbs with.

At this point, I am still in assessment mode.  Everything seems fixable but it is a little overwhelming when there is multiple issues happening at the same time.  It is a great case of a good bike with crappy previous owners.

Offline Boomer

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Re: Questions on my new project bike.
« Reply #4 on: December 03, 2019, 11:02:15 am »
Measure the resistance between coil cap 1 and coil cap 4. Should be a little over 10Kohms. If it's substantially more then you need to unscrew the caps from the cable and check each cap as the 5Kohm resistor in one have gone high-resistance. Replace the damaged plug cap, or if yer feeling rich, replace all 4.
I use NGK SD05F-R plug caps and they work jes fine.  :)
If yer replacing all the caps buy some 8mm stranded copper core spark-plug lead and replace the original wires while you are at it.
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Offline connieklr

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Re: Questions on my new project bike.
« Reply #5 on: December 03, 2019, 11:35:15 am »
Measure the resistance between coil cap 1 and coil cap 4. Should be a little over 10Kohms. If it's substantially more then you need to unscrew the caps from the cable and check each cap as the 5Kohm resistor in one have gone high-resistance. Replace the damaged plug cap, or if yer feeling rich, replace all 4.
I use NGK SD05F-R plug caps and they work jes fine.  :)
If yer replacing all the caps buy some 8mm stranded copper core spark-plug lead and replace the original wires while you are at it.

Believe that's 7 mm wire Boomer. You'd have a rough time getting 8 mm through the caps, grommets, and ferrules.
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Re: Questions on my new project bike.
« Reply #6 on: December 03, 2019, 01:51:19 pm »
Wageslave, the C-10's have a nasty habit of hydrolocking if the carbs are overflowing. This can happen while cranking.
So, do not try to crank the engine if you smell gas.

Before you get too deep into this project, check that the engine was not hydrolocked previously.
There is a video available that shows how to do this easy process.
https://www.youtube.com/watch?v=4W6k3pTdAXw

Weak spark is often cause by bad wires/caps, or poor connections at the coils.
Check that all the wires are secure on the coils.
Murph sells a set of wires/caps that works great.
https://www.murphskits.com/product_info.php?products_id=51&osCsid=J2Ck75j-WX3LlIuwYtVcV1

Additionally, the ground near the CDI box may not be good.
Check the ground, and I also suggest; do the free power mod as it solves this possibility.
https://www.youtube.com/watch?v=RFK3AaZ_Uwo

On your spark, have you checked that the wires are on the correct plugs?
Many folks cross the wires...

Ride safe, Ted

« Last Edit: December 03, 2019, 02:06:18 pm by connie_rider »
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Offline Boomer

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Re: Questions on my new project bike.
« Reply #7 on: December 04, 2019, 03:14:44 pm »
If yer replacing all the caps buy some 8mm stranded copper core spark-plug lead and replace the original wires while you are at it.

Believe that's 7 mm wire Boomer. You'd have a rough time getting 8 mm through the caps, grommets, and ferrules.
Yeah, what Guy said.
Damn, gettin' old sux! :rotflmao:
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Offline connieklr

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Re: Questions on my new project bike.
« Reply #8 on: December 04, 2019, 07:06:23 pm »
If yer replacing all the caps buy some 8mm stranded copper core spark-plug lead and replace the original wires while you are at it.

Believe that's 7 mm wire Boomer. You'd have a rough time getting 8 mm through the caps, grommets, and ferrules.
Yeah, what Guy said.
Damn, gettin' old sux! :rotflmao:

Tell me about it.

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Offline MAN OF BLUES

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Re: Questions on my new project bike.
« Reply #9 on: December 04, 2019, 07:20:30 pm »
It came with no key, so I unplugged the ignition and jumpered the connectors to make it think it is in the run position.

It cranks over fine, but doesn't want to even start on ether. 

Yeah, I'm in the "old" zone, but I still have to question if the procedure done, actually quantified "complete" or correct, to make it start.. as I have never cut the harness, and jumpered same, to make the bike "run".. so I don't know what wires were or were not connected.../\ :??: :??:

Conni's are funny, the J-Box/relay syndrome may make it possible to turn over, but ..... will it start.. just keep cleaning stuff for now, remove the tank, get that bastiche clean, realllllly clean, pull carbs, clean them..... and go on when you get the new ignition switch..

 ;) ;)

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Offline Wageslave

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Re: Questions on my new project bike.
« Reply #10 on: December 04, 2019, 10:32:07 pm »
The ignition switch plug was jumpered to match the connection table on the wiring diagram for the ON position.  I actually received my new lockset and the replacement switch tested the same on my multimeter.
I did the hydrolock test, and all cylinders seemed good.
I checked over the spark plug wires and found the resistance between 1 and 4 to be about 25k.  I will try to locate a new set of wires the next time I can get to the dealer. 
I pulled the fuel petcock and fuel door off of the tank, and found more orange smoothie inside.  It actually smelled like latex paint, and was not even a little flammible.  I have most of it poured out, but like most tanks, there is about a cup left in there that I cannot get to come out for anything.  I am probably going to pour some used motor oil in there to displace the water, then give it a good diesel scrub.
I'm probably going to pull and disassemble the carbs next but if the tank is any indication, it's going to look like a crime scene inside those float bowls.

Offline Lee

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Re: Questions on my new project bike.
« Reply #11 on: December 04, 2019, 11:30:51 pm »
The coils fire during cranking, but the spark is weak on the 1 and 4 plugs.  Both coils measure about 24 ohms between the - and + connectors,  The left side coil measures full battery voltage at the - and + terminals, and you can see the trigger signal pulsing during cranking.  The right side coil measures about 1.5 volts, and also pulses during cranking.  Continuity checks good between the CDI box connector and the four terminals at the coils.

At this point, should I replace the CDI box or is there something else that I should be looking for to get fire?

Thanks

No to replacing ignition box. That until this anyway. Would think reduced voltage at 1.5 on right coil needs addressing first and foremost. Pink elephant unless someone tells you it is normal for this on start. Check wiring and all connections in that path first and foremost. Also since you have two coils & two pickup units you can switch or jumper leads to see if weak spark switches side for process of elimination of parts involved. This not to start bike but to test with plugs out of engine.

As noted these bike are prone to hydro lock and bending rods on startup. I would not run fuel till I knew carbs were up to snuff and had overflow tubes.

I took an 87 back to the living after 12 years sitting. The j-box is the first choice for electrical gremlins. I resoldered the back of the board after checking diodes and changed the relays. Had to rebuild brake system and clutch slave cylinder. As well fuel system in total including lining the tank. I was rewarded with one hell of a bike!

Did other things as well but that is for later. Above will get her done to ride reliably and safely. Get 12v to both coils!

Offline Lee

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Re: Questions on my new project bike.
« Reply #12 on: December 04, 2019, 11:39:07 pm »
PS: Carefully check and clean contacts at j-box and ign box if you have not. Oil, dirt,& corrosion can be a low voltage issue. Contact cleaner and modified toothbrush will help. The gods of motorcycling abandon cyclist on the side of road in the cold and dark for dirty contacts. Mortal sin you know.

Offline Lee

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Re: Questions on my new project bike.
« Reply #13 on: December 05, 2019, 04:29:19 pm »
Had a min to look at the fig. 2 schematic that circulates on board this morn. For testing purposes with plugs removed from engine but grounded. I would switch coil leads to see if weak spark moves with coil attached to black and red normally # 4 coil. You could just switch black and green leads but there still could be a problem with the one  common red connector. If problem stays with red and black, I would then check black lead back to Igniter box as well the red connector over to next coil.

With regards to pickups. Switching is physically more difficult due to connectors. But could be done with jumper wires or switching connector pins by following and reversing color coded wires at Igniter box. This would isolate problem to a component or wire path.

1.5volts is trackable back to where full voltage exists normally in circuit. Just a process of elimination to find where voltage drops out. My bet would be black wire to coil or p/u as all else is common to both coil 12v circuits.

I mentioned earlier that there may be a circuit designed to start just with full voltage to one coil. This is speculation based on your current readings being normal at 1.5v. This unless someone knows for sure about how Igniter could do this in any way. I do not see this in the circuit.

Of note also the Fig. 2 schematic circulated on board does not show p/u in circuit! You will have to go to manual schematic.

Please note I am not an expert here. However have spent a portion of my life in a general electrical repair facility. Items brought for repair often had little info to no for the repair. It was necessary to just follow the wires and do a process of elimination. Now it is just replace a circuit board! Much easier as it works or does not! Good luck!