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

 

So your sure your getting fuel and spark... How is the compression

 

I have not put a gauge on it, but I can feel the thump when I put my finger on the spark plug hole, and the exhaust is giving a good puff of air. I know I have spark when the plug is outside the cylinder which should mean I have spark with it in. I can smell fuel on the new plug after turning it over for several minutes - in short bursts of course. What really makes me wonder is when I shoot starting fluid in either the carb or the cylinder itself is that I don't get a little action. You usually get a running atv when you do that otherwise - for a few seconds at least. That's what makes me wonder if I lose spark once completely grounded inside the cylinder because of a safety switch. But I've checked all those too!

Other thoughts? What else can I try?

Thanks!

bz

 

I would try jumping it with another battery or replacing the existing!

 

Sounds like the valves need to be adjusted.. set them both at .004

 

I'd like to know the compression for the heck of it or like spliffy said check the valves. My kids have a little 50cc mic motorbike that was a hard starter....turned out to be a tight valve!

 

I have the same exact problem....On the same bike......Ran fine a few weeks ago....
Does anyone know the valve setting procedure?

 

Here is a good Youtube video on the valve adjustment procedure. http://www.youtube.com/watch?v=HppcqVpnaFw

I've done this and still have a non-running atv. I tried the CDI from this atv with another 50cc atv that I have and this one still won't start, but the other one will with this CDI. I'm hoping that I can get it running soon. My biggest point is that it won't even try to start with ether in the spark plug hole! This is what perplexes me the most!

 

can you make a video of you trying to start it, perhaps someone can hear or see something your not seeing/hearing!

 

Hey guys - I have a running ATV! I tore it apart today further than I had before, and verified top dead center, adjusted the valves, put it back together and it FIRED! It's running! Thanks for all your help! I have to adjust the carb (airflow and idle) to get it perfect, but it's working again!! The kids are HAPPY and so is DAD!

Thanks.

Brad Z