New 66CC will not run.

A_DangerrX · #1 02-06-2010, 03:34 PM

Hey everybody,
I've been riding with a 50CC for a while now, but I gave it to a friend and I got a new 66CC to play with over the winter. I've got the bike all set up with the new motor, but the damn thing will not start. I've done hours of reading around the site and I have tried everything I could find. Here's what's going on and what I did:
Symptoms:
-Engine sounds like it has compression when I'm pedaling but refuses to actually run.
-Unburned fuel coming out of the exhaust.
What I tried:
-I checked my on/off switch setup for continuity, no problems there.
-Checked for spark (there is spark).
-Checked spark plug gap. It's at .025".
-Opened up carb, checked the float for cracks or anything, checked for debris, checked C-clip (It was on the 3rd notch down from the top the first couple of times I tried to start it, I moved it up and it still doesn't work).
-While I had the spark plug out, I pedaled around for a bit with the throttle wide open to clear the motor in case I flooded it.

Obviously the fuel isn't igniting, or at least not igniting fully. Is it possible that even though there is spark, it's not strong enough? I have exhausted my limited expertise with these motors. Perhaps somebody with a bit more knowledge can figure this out.

Nougat · #2 02-06-2010, 04:46 PM

Weak spark is possible. Try a known good plug, or at least replace the stock one with an NGK B6HS.

What's your fuel mix? 16:1 is too much oil. As an example, I started my bike on 16:1 ("following the instructions, before I learned), and it did run, but when I tried to put the same fuel in the snowblower at the beginning of the season, it wouldn't start, even though I had cleaned the spark plug. I remixed to 28:1, and the snowblower fired right up like it always does.

Another thought would be that there's an air leak somewhere on the intake side, and the engine is drawing too much air, making it too lean to ignite. Common air leak places are between the intake and carb (use clear silicone here), and at the carb top (I think you can use clear silicone here, too).

One more thing to check is the choke. Make sure the choke is in the right position. Up is on, to start in the cold, down is off, to run after starting or start in mild to hot weather. Make sure the choke cover over the carb intake isn't loose; remove the air cleaner to check, and adjust/tighten the lever as necessary.

**Norman** · #3 02-06-2010, 06:22 PM

this can be a pain to do. mark the mag rotor so you put it back on the same way you take it off
Take the mag coil and then the mag rotor off see if the key is sheared. If it firing the spark plug,and has fuel it should at least pop. Other wise it has a key missing or sheared my best guess.
When its out of time it won't run found this on a few engines.
On thing make sure when looking at the mag rotor the slot is leaning towards the right a little bit
they are slotted off true to the hole so the key way on the rotor looks strange. Proper way to put them on is with the rotor key will have that ever so slight lean to the right or towards the front sprocket.
Ho this will help.

A_DangerrX · #4 02-06-2010, 06:48 PM

The mag rotor is on the same side of the motor that the drive sprocket is on, yes? I'll check this after dinner. There IS definitely spark. If this turns out to be a timing issue, what can be done? From what I've read adjusting the timing on the average China 2-stroke is nigh unto impossible.

NerpAngel · #5 02-06-2010, 09:41 PM

Well I'm not sure about troubleshooting with engine parts, BUT what I do since my engine had EXACTLY the same problems as yours did is to spray a little bit of ether into your air filter, THEN try running it. My engine is naturally cold if I don't run it for a month so I have to spray that in there to give it a little extra push. Just unscrew your air filter off your carb and spray a tiny bit of it into your carb where your throttle pin is.
This works for me everytime.

A_DangerrX · #6 02-07-2010, 01:21 PM

Sunday morning status report:
Bike is still nonfunctional. Norm, I opened up the engine and took out the mag coil to get at the rotor as per your advice. I took off the nut and washer that secure the rotor, but the thing itself will not come off. I can move it about a quarter-inch, but it won't go any further. Could a screwed-up key cause that, or am I just not applying enough force? I don't want to break anything that isn't already broken.

Nougat, I'm running I think 24:1 or maybe 28:1 for break-in. I used the same mix on my 50CC with no problems. Soon as I can get my hands on a replacement spark plug I'll try that. I'll try the sealant thing, too.

One more issue that has come to my attention: Unburned fuel has dripped out of the joint between the exhaust pipe and the motor. Could a leak there be affecting ignition?

Nougat · #7 02-07-2010, 04:22 PM

Quote:

I'm running I think 24:1 or maybe 28:1 for break-in.

Well, that rules out a bad mix, then.

Quote:

Unburned fuel has dripped out of the joint between the exhaust pipe and the motor.

Doubtful. A two stroke will run with no muffler at all, although it'll run badly, because the backpressure of an exhaust keeps the next charge of unignited fuel/air in the top of the cylinder.

Cabinfever1977 · #8 02-08-2010, 04:33 AM

Quote:

Originally Posted by A_DangerrX

Sunday morning status report:

One more issue that has come to my attention: Unburned fuel has dripped out of the joint between the exhaust pipe and the motor. Could a leak there be affecting ignition?

When i had a bad/worn out exhaust gasket and had a leak,it would be much harder to start.
I put in a new exhaust gasket and tighten the nuts and wammo its starts right up and starts up the first time every time now.

**Norman** · #9 02-10-2010, 07:57 PM

Can you see the key in the rotor shaft? Is the rotor key way and key way on the shaft alined?
It might be too hard to see both. But if the key is sheared or not even there it won't run.
You can't turn the rotor by hand or some light force with the gears locked (shop rag wedged in between the teeth of both gears) on the other side(clutch side) can you. If you can turn the rotor with the gears locked the key is toast. Then you will need to take the rotor off to replace the key.
The rotor is a booger sometimes to take it off. gently wiggle it to work it off.
I made a small hooked tooth pry bar for those hard to get off rotors made it out of a 10" length of 1/4" key stock heated up one end and beat a small hook on its end to get under the rotor to pry up on the rotor
2 of the pry bars will work better than one. you can work the rotor from both sides then.
If you plan on leaving the rotor off wrap the rotor with a band of mild steel. Metal from a tin can will work wrap it tightly so the rotor contacts the steel on the curved parts a stainless steel hose clamp is not good has to be mild steel from what I've been told. I'm finding that the rotors "may" loose the magnetic force if left on the bench for a length of time if this is not done. But I do not know how much it effects the rotor as I've just lately found this out from people that recharge magnets. I never worried about the rotors before but doing this should not hurt it and is probably better for them.
you can do a search "magnet charging" or "magneto recharging" for more information it may be these magnet rotors don't need this but why chance it(seems like black magic or Voodoo). A lot of the info pertains to old, real old magnetos. Depending on the material the magnets are made of will also matter if you need to do this or not. I do not have any idea what type of steel the china magnet rotors are made from.

jay sawdust · #10 02-10-2010, 11:06 PM

Just a thought....I had a motor that showed spark when motor was spun...so i spent the rest of the day going through the whole motor....In desperation I switched out the cdi from another bike and it fired right up....if your friends cdi is handy you might want to try....Just thinkin....anyway I learned a thing or 2 form norm on this thread....ty.....J