Replaced spark plug cable- no spark :(

mynakedrat · Nov 9, 2013

SO I went to autozone and got a replacement. unscrewed he old cable, cut the new one, hooked it all together, it sparked for a few feet, then nothing
I opened up the cable, and I see there is no metal in it>? It was just insulation
So I grabbed the old cable, changed out the boot, hooked it all up, still nothing.
Put everything back the way it was, still nothing.
Did i fould a spark plug?
Is it the wire?
Did using an insulated wire fry my cdi?
What I have done: I took the leads coming from the magneto in my hand, and at speed it is shocking me.
Tried to put my finger on the screw on the cdi, i get no shock.
Do i need to be grounded? Is there another way to test without a mulimeter? so far its either cdi-spark plug cable- spark plug that are the issue. I need this running by monday, so i may have to make a new cdi.
Ideas? Any way to test the components that i have narrowed it to?
I tried two different spark plugs with no success...

MEASURE TWICE · Nov 9, 2013

The new cable probably is the kind that has a carbon coated cloth twine inside. That is also a conductor that is used instead of copper wire. It I would guess is just fine. I expect maybe when changing the cable something might have caused something getting ready to go, just to go at that time.

I have a Briggs engine and others would be better to help you on your particular engine.

I would mention that I have had some magnetos that when there old, the magnet wire that connects to ground became brittle. It cracked inside the insulation. Worse at one point it broke right as it enters into the epoxy coating. I grabbed a solder iron with a crummy tip to just melt away the epoxy enough to get a tiny piece of wire to solder a wire back onto it using a good tinned solder tip.

I used high temp RTV to make a good strain relief over the repair.

MT

mynakedrat · Nov 9, 2013

Well its a new engine, and I just saw and checked the magneto wire.
Funny thing is, i just got back from trying to start it. I can smell gass, and after a block of heavyass pedaling, it finally started to fire and took off. I got where i was going, turned it off, then jsut now tried to start it up again. No go. There were a few spurts, but eventually just nothing at all.
Fouled plug maybe?

crassius · Nov 9, 2013

I'd look for a wire connection that is loose or maybe a wire that broke inside the insulation that sometimes makes no contact.

mynakedrat · Nov 9, 2013

I think the fuel may be running to rich for some reason?
So i made my own spark cable with speaker wire. Spun the wheel with plug on end, no spark.
So i noticed there was a little gap in the head/top end. I checked the bolts--- barely even hand tight. New motor ~200 miles, so they pobably vibed off. While top end was off, i hooked up the new plug i got a few days ago. NGK. taped it to the head, and saw a little spark after a revolution. Torqued top end back on(hand tight plus two turns) and put new plug and wire assembly back on. cleaned carb slide, cleaned filter, then took it out. wouldnt start unless choked, but it started with more force than ever! sputtered a bit and died (i left the choke on) got it started, buut seems real rich, and over revved (again) when pulling clutch. strong gas smell. i adjusted the idle screw out, and tightened the throttle cable closest to the carb. its cold and dark now, so will have to wait to find out why so rich.
Oh, engine seems louder with new plug/bolts tightened.

maniac57 · Nov 10, 2013

All of the kits I have built came from the factory blubbery rich( I think they try to avoid warranty returns and don't care HOW it runs as long as it runs longer than the warranty period)
I set the needle second groove from the top during break in.
Wait until at least 200-300 miles before trying to tune for max power.
(most engines will respond well to a slightly smaller main once fully broken-in)

2door · Nov 10, 2013

Two things:
First you say it smells like fuel (rich). This could indicate a stuck or clogged float valve. Did you clean the fuel tank before installation? Are you using an in-line fuel filter? You should be.

Then you mention that it "over revs". This sounds like either you have an air (vacuum) leak, probably where the carburetor attaches to the intake manifold or the manifold where it attaches to the cylinder. Also are you sure the throttle is working correctly and is adjusted right? If the engine will run with the choke on that is a good indication of an air leak in the induction circuit. Seal the carb to the intake with a gasoline compatible sealant and check the gasket at the intake and cylinder. The kit gaskets are notorious for early failure and leaks. Make a new one from good quality gasket material and torque the fasteners to about 60 inch pounds.

One more thought. What is your fuel to oil ratio? The kit instructions probably told you 16:1. That's too much oil. Drop your ratio to no more than 24:1 and give it a try.

Tom

mynakedrat · Nov 10, 2013

I am using an inline filter , not the one that came with the kit. I did not clean the tank before isntall though

I did find a leak, and fixed that . it was in the carb pipe. The trottle is working correctly, but i am not sure where to adjust it to. I usually adjust it while riding, as the engine does different things at speed, or when it is hot, or cold.
It will not run with the choke on.
Gasket looks good.
Not sure what it is torqued at though.
Fuel to oil is now what is recommended on the bottle, 4oz to 1/2 gallon.
which is 32:1

crassius · Nov 10, 2013

mynakedrat said:
Fuel to oil is now what is recommended on the bottle, 4oz to 1/2 gallon.
which is 32:1

gallon is 128oz - 1/2 gallon is 64oz

4oz oil to a 1/2 gallon is 16:1

mynakedrat · Nov 10, 2013

oh so i can use less oil?

xseler · Nov 10, 2013

mynakedrat said:
oh so i can use less oil?

I'm using Echo 2 cycle oil at 50:1 ratio...............2.6 oz to a gallon. Many on here are running Opti-2 oil at 100:1 ratio.

The suggestion of 32:1 would be a good 'break-in' ratio.....as long as you're using a good quality oil.

Good luck in your project!!

crassius · Nov 10, 2013

yeah, I'd go with 32:1 after a bit of break-in

mynakedrat · Nov 10, 2013

So its working again. I was able to right all the way out, and back, but right before i got back to the house, it started sputtering again. SMH. It was going so well.

xseler · Nov 10, 2013

These machines will surely make you smile, however, there's a few that certainly make you work for it!!

mynakedrat · Nov 10, 2013

Yea. that is true. I like the work. Its worth it. Peoples reactions are priceless going down the road at cruisin speed

crassius · Nov 11, 2013

at about a mile or so, these engines warm up enough to start running reasonably - at about 8 to 10 miles, they are finally warmed to a stable temp that will change the running a lot - it is difficult to tune for both conditions

mynakedrat · Nov 11, 2013

I have seen that. Toady, it was really slow to start, I thought I would have to pedal to work, then it finally just started up . Still unsure whats up with that. Ran fine, but sputtered a couple times. It was running really good at the five mile mark. On the way home it sputtered again . Maybe i just have some bad gas? I dont understand the inconsistency, from ride- to start up, to warm up. Weather?
Thanks for your repleis on this thread and others... its definetly getting better!

CTripps · Nov 11, 2013

The temperature will have an effect, you can run a bit richer in cooler weather. Make sure you close the choke when you try to start it when it's cooler. Once mine fire up (from cold) I can usually open the choke within half a minute, but I wait another half minute or so for the idle to steady out with the choke open and giving it a little gas for it to really wake up.

MEASURE TWICE · Nov 11, 2013

If its really cold ambient air temperate outside, as I see your location, starting can be difficult. I had trouble with an old two stroke motor cycle when I lived in New York during winter. If it did not start with a few tries, the plugs would have to be dried from raw gas shorting the plug out.

Is there sometime made for two stroke engines that takes the place of like in a four stroke engine oil dip stick heater? Although the motorized two stroke bicycle engines don't use a battery for ignition circuit, I found with the old two stroke motor cycle engine that did use the battery for ignition circuit, I had to take the battery out and plunk it into some warm water for 5 minutes and then transfer it back to the motor cycle to help get the bike started easier.

MT

maniac57 · Nov 11, 2013

I know my Pig runs quite a bit better in cold dense air. It's enough to easily feel the difference when it hits the pipe.
Never had any starting problems even below freezing. Fires right up with choke, then half choke a few minutes more and she's ready to roll.

Replaced spark plug cable- no spark :(

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