Nc35 starting issues- never ending issues...

[Skim325]

Ok so been slowly working on the nc35 as I get time on the weekends.
After doing a minor carb rebuild and started up the bike noticed that the bike was difficult to start and eventually when it did sounded rough and would have difficulty starting on.
After doing a bit of trouble shooting I figured I would touch the exhaust pipes to make sure all cylinders were firing and lo and behold the front two headers were cold while rear two were hot.
So here are the things I did thereafter. Need some advice and help to make sense of things.

I pulled the front two spark plugs. They had a little bit of oil on them, primarily where the threats were. Not a lot. See picture below.

Then I started checking electrical stuff. I pulled out there Multi meter and this is where I started to get really confused.

The Haynes manual started the following.

“Ignition HT coils
Primary winding resistance - 2.5 to 3.5 ohms at 20 degrees Celsius
Secondary winding resistance
With plug cap- 14.0 to 25 k ohms at 20 degrees Celsius
Without plug cap - 12.0 to 14.0 k ohms at 20 degrees Celsius”

And here are my readings of the cylinder coils and coils. Note coils were still plugged in to the cylinder coils at the time of reading and negative terminal was removed from the battery

Front coil reading at 20k ohms - 2.41
again at 2k ohms - 1.837
Front cylinder coil at 20k ohms - .84
Again at 2k ohms - .258


Rear coil reading at 20k ohms - 2.72
Again at 2k ohms- No reading (kept dropping to 1)
Rear cylinder coil at 20k ohms - .86
again at 2k ohms - .252

From what I can tell the only readings that seem to line up are the primary winding resistances and the coil readings at 20k ohms.

According to the manual the next step should be to take off the coil from the cylinder coil and measure that but I ran out of time.

In you your opinions can you guys make sense of the info? I wasn’t sure if I should be measuring at 20k, 2k, or 200 ohms on the multi meter. Those were the only options aside from 200k ohms.


Spark plug picture below:



Sent from my iPad using Tapatalk

[magg]

200 ohms range to measure primary resistance. 200k ohms range to measure secondary resistance. If you fit plugs to plug caps and rest both plugs on the rocket cover and crank engine, with run switch on, you should get spark.

[Suzuki416]

check your earth on the front carbs

[Skim325]

check your earth on the front carbs

check your earth on the front carbs

Ok so finally got some time again to work on the bike.
I was going around getting some ohm readings on the coils. Seemed like for the most part there was continuity, despite one of the front coils giving readings a bit off from the others.

Getting a primary child reading on the front two coils (unplugged from the bike) gave
.643 and .604
While the rears gave .648 and .696

So I went and started checking for ground per your suggestion.
I connected the positive terminal, left negative unplugged. And with the multimeter set to 200ohms, started touching around the bike. Most parts gave off readings consistent with each other except for the front cylinder head. Checked rear cylinder head, and rechecked the front. Looks like the front cylinder head is not grounded. So started looking at some of the wiring, and found a possible culprit.

See picture.



Looks like one end comes from the wiring harness, and the other end plugs directly in to the stator on the left side of the bike...
Looks like I‘lol need to fallow a wiring diagram to see if this cable leads directly to the front carbs or not, perhaps there is another short somewhere else too...

Wonderful...


Anyway. Thanks for the suggestions everyone, I’ll keep updating here as I slowly work on the bike.


Sent from my iPad using Tapatalk

[magg]

Your description suggests the connector from the output of the alternator to the main loom has failed, a known failure point. Results in no battery charge and eventually the bike runs poorly and will not crank to start.

[Skim325]

Can you explain the runs poorly part? How do? If you look at one of my previous posts, I uploaded a video of my bike running poorly and with bursts of power when on the throttle.

Also, is this an easy fix? Seems like I can rewire the connectors tips but if this is a known issue, any suggestions on how to resolve this problem for good?


Sent from my iPad using Tapatalk

[Vincent]

The three yellow wires coming from the stator often corrode a bit where they connect to the main loom. This causes increased resistance, and generates a lot of heat, and melts things. It's very common to see the standard plastic connector melted and burned.
I would recommend wiring them directly together, and then insulating and heat shrinking. This should solve your problem.

Although it looks like there's a lot of burnt wiring in there, so it might pay to replace those other connectors too.

[Skim325]

When you say wire them together, would you recommend foregoing connectors, and just solder them together directly?


Sent from my iPhone using Tapatalk

[Vincent]

You could do that, I think it's what a lot of people do, or you could buy the plastic connector from Rick Oliver for a couple of pounds.

I initially just twisted mine and insulated with electrical tape, and then later got a replacement connector when I was ordering a few other bits.

[Vincent]

Also, regarding your running issues, poor output from your stator (due to melted cables) can cause firing issues in your ignition system. So hopefully sorting those will solve your ignition issues.