110cc wont start

[cgerb73]

Hey everybody,

Well I think I have it figured out but I want to run this by someone before i put time and money in.
The engine cranks and is getting gas. It pops as if gas in cylinder is ignited but wont go. I read a few other posts where the member figured his motor lost compression and rebuilt. I dont have a compression gauge to fit this plug hole so I was able to shoot air into plug hole from my compressor and opened the oil fill cap. Air was coming right out the oil fill hole. Now to me that says the rings are shot. Is this true.
The other thing is if I put my finger over the spark plug hole and push the go kart while in gear I feel the suction. This is what is making me question what I posted above.
Thanks in advance
Gerb
p.s. Where can I find a compression gauge fitting that I can use with my gauge for bigger engines?

[metalstudman1]

Depending on where the valves were when you shot air into the cylinder it would put air in the crankcase as you have oil holes in the head.Is it a used engine? Also local auto parts store or Napa sell a kit that has different threads for an automotive compression gauge-I haven't bought one yet because it's like $60.This may sound funny but when I put my finger over the plug hole and pushes my finger away easily it's usually about 120+ psi !!!If it doesn't have enough compression to push my finger away it's 60psi or less.

[cgerb73]

Thanks for the clarification. I'll try the valves at different positions and see what I get.
I definitely dont have the compression to push my finger away. I am guessing 120 psi is what I should be getting? Yeah, $60 is a little much, not that I am against adding more tools to my collection.
Thanks
Gerb

[SYCARMS]

I would some how find a compression gauge to use. Figure your cost of rings, piston gaskets and time involved. If your guess is correct your in good shape but if not you have wasted all that time and parts. Look on the internet for a gauge with the rubber tip, you just press it in the plug hole and crank the engine, this type will work on any engine. I got mine @ Auto Zone for 30 some dollars. You can also check harbor freight.

TOM

[cgerb73]

Ok, just an update. I went to harbor freight and got a compression gauge set for 19.99 on sale. It actually had the right screw in fitting for the smaller plug size. It also had a handfull of different fittings and a case.
Hooked it up to the engine and cranked it over. The result was 0 psi. I thought the gauge was broke so i tried it on my outboard motor, well the gauge is not broke! So, I started taking everything apart. I found that the piston had a nice gouge along the side and knocked the top edge off of it.
SOoooo, i guess a rebuild kit is needed. lol.
let you all know when this gets going.

Gerb

[SYCARMS]

What done the damage to the piston. You will need to check your valves. They may have hit the piston, and if so you will need to determine the cause.

TOM

[cgerb73]

Good suggestion. I dont recall damage to the valves. I'll have inspect closer. The damage was on the outer edge of the piston. Is it possible that it caught the bottom of the sleeve. I am at work now, will check later.

Gerb