Starting issue - ran a week ago! HELP

[bazeven]

Kazuma 50cc ran last week.  Pulled it out to let the kids play, and can't get it to start. 

Has fresh fuel
Fuel getting to carb and into cylinder
Has spark while grounding to block - even tried a new plug (plug wire sparks to engine even without spark plug in - is this an issue?)
Starter cranks and turns over
I've tested the rear and side safety switches
headlight comes on dim while trying to start
Tried some starting fluid in the carb and in the spark plug and doesn't even try to fire - usually a little eather will make it pop...  This is where I'm stuck.

What am I missing? 

I tore the carb apart and cleaned it all up so that's good

I'm wondering if a safety switch is still grounding out the plug, but would I get spark out of the cylinder then?

Normal starting sequence - turn key on, crank starter.  Brake does not need to be held down on this model.  Back safety switch is open until pulled, then ohms out.  Side safety switch is closed and opens when pulled off.  Handlebar switch is on - when off, it won't crank. 

Thoughts?

We'd love to take this with us this weekend, but as it stands now, Dad can't get it to run!!

Thanks!

bz

[cammoman]

I am pretty sure there is an ECU on that unit. I would check that out if you have'nt already.

[Thumper700]

ECU or CDI?  Isn't an ECU for an EFI machine?

[cammoman]

Was'nt thinking! that would be a cdi

[toodeep]

If it has fire more than likely the CDI is good. What do you mean the plug wire sparks even without a plug? It sparks from the end or from somewhere in the wire (like towards middle)? If it's from somewhere in the wire besides the end then that could be the problem. The dim light makes me think the battery might be a little weak also, try it with a booster pack or charger on it.

[bazeven]

With the spark plug out of the boot, and I cranked over the engine, I can see the boot (away from the spark plug end) spark back to the block.  Through the boot to the motor.  I thought this was strange.  The boot shows no signs of cracking or wear, but it sparks right through the rubber part to the block. 

Do I need to adjust the valves?  Since it doesn't even try to fire even with starting fluid, I'm wondering if it's valves.

bz

[Moby]

I vote valves

[toodeep]

I would replace the spark plug cap/resistor cover/boot, whatever you want to call it. Should be able to get a replacement for under $5 and anytime voltage can leak to a ground is not a good thing. What kind of spark plug are you using? I've had the best luck with the NGK brand in atv's. Valve adjustment won't hurt anything but I don't think that is the problem. If it ran good when parked I'm still guessing a weak battery and not turning the motor over fast enough to get it going. Another thing might be low compression from a sticky valve, etc. You can just put your finger over the spark plug hole with pressure applied and turn the motor over and it should pop your finger off the hole (not a real accurate way but an easy test).

[Andy]

If it has a pull start try useing that, as you can turn them over alot faster than the starter will.

[bazeven]

No pull start here.  Have tried to jump it and have completely charged the battery.  I feel it's turning over correctly.  I tried my finger over the spark plug hole and it did pop it off.  I'm also getting a nice puff out the exhaust.  I'm going to try valves next week and see what I come up with.  Either stuck or needing to be adjusted.  I'll also try to find a new plug boot to avoid the spark through that part.  Using a new NGK plug.  The thing that really gets me is that I don't get even the slightest pop when I use starting fluid right in the plug.  Crazy!  Any more ideas, send them my way.  I'll let you all know what I find out.  THANKS!

Brad Z

[toodeep]

I have had one of them cheap scooter's in the past that I worked on and it came down to the spark plug end cap/boot as one of the problems (battery was the other). If you have another bike sitting around just try it and see if it works, they just unscrew from the coil wire.

[bazeven]

Still no go!  Replaced the spark plug boot today - now it doesn't spark through.  Still no go.  Still have a good strong spark.  Checked and adjusted valves.  Re-checked all wiring and safety switches...  everything looks good.  Compression feels good, but I don't have a gauge that fits.  Since I'm getting spark, does that take out the Coil, CDI and the Voltage Regulator as bad parts?  If I unplug the CDI, the bike still tries to start but won't fire.  If I unplug the volrage regulator, the bike still tires to start, but still no fire.  The battery has been charged, and I've tried with a 2nd battery jump start.  I have fresh gas, and have good flow to the carb.  It will turn over all day, but won't fire.  Any other suggestions?? 

Thanks guys!

Brad Z

[stumper]

Sheared flywheel key. Its not firing in time with the compression stroke

[stumper]

Any luck?

[toodeep]

Ya, this one ran me out of ideas. Would like to know if you found anything out.