Do you know which screw is which??

 

The one that was faily flush on mine was the air, the one sticking out was the idle. Using a different carb so this is by memory.

 

When you cleaned out the carb did you take it all the way apart? It sounds like there is still something blocked.

 

We took it apart as far as we dared...we sprayed carb cleaner in every hole and orifice we could find and made sure it blew out somewhere. I'm pretty sure it's clear...but I guess anything is possible.

 

Try pouring a little gas into the spark plug hole. It should fire up. Your compression reading seems a little low. I think it should be closer to 130. If it doesn't start with the gas in the hole trick, you most likely need a new piston and rings.

 

I tried pouring gas in the spark plug hole, I've tried Ether in the carb, I have tried the carb adjustments mentioned. I still can't it to fire up. The engine coughs a little when I do these things, but my neighbor (who has lots of dirtbike two-stroke engine experience) and I are pretty sure its either:

- the carb settings
- the amount of spark the plug is generating

It seems like the engine is getting TOO much gas or not enough spark. The Sundiro has an electric choke. When trying to crank it electrically, it coughs a few times and then stops coughing as it gets more fuel in the chamber. The spark plug is quite wet.

Since all this started after carrying the 4 wheeler cross country while moving in a heavy rain showers all day, I'm wondering if the coil is slightly damaged to the point that the spark plug fires, but it's not hot enough.

The other possibility is that the plug gap is wrong. Does anyone know what the gap should be on a 90cc engine like this one?

Also, could the coil be damaged where it still gives a spark to the engine, but not enough of one?

Again - thanks to all of you for the suggestions...

 

Unfortunately it may be time to take to a shop.

 

New progress!!!

I went by a shop here the sells Polaris ATVs (it's a lawn mower shop) and looked at their 90cc Polaris. I was checking out the carb settings (I felt like I was spying) and wound up talking with one of the maintenance / tech guys. After I described all my trouble shooting, he suggested the exhaust was probably clogged. He recommended opening it up or taking it off and trying that.

Well, I had to take off the muffler at the engine mount (it's all welded solid)- but it now fires up with Ether sprayed directly into the carb. It has coughs and fires up with gas sprayed directly into the carb. WHOOOHOOO!!! Progress.

Now - it seems that the remaining problem is my carb. I am thinking I need to soak it again. Thoughts?

 

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OKAY - another update and request for help - again.

A friend of my neighbor has looked at my sons ATV and concluded that the problem is the timing. It has fuel, compression, and spark - apparently just NOT in the right order.

Does anyone know the timing settings for a SUNDIRO 90cc 4wheeler? I assume the settings for an Eton or Polaris would work.

THANKS IN ADVANCE!!!