ATV Florida Forum

Ok i took the head and jug off a motor of mine. its a 2 stroke. came off a honda cr125

Is there supposed to be gas under the piston? it dont seem right to be gas. i drained all the anti fezze..
if someoen needs a pic ill go take one..its in the arena where the crank shaft is? someone tell me is ther supposed to be gas down there?

well it is suposed to be wet under the piston, but do you have like a large amount of gas in the lower end?? then you may have some serious worn out rings or some other probs than, possibly even a crack somewhere in the piston.

Just ran across your post.  Yes there would be gas under there. I had mine apart about 3 years ago so it's kind of fuzzy now but here goes.  The piston goes up creating a vacuum underneath that pulls the fuel/air misture in through the reed valves.  When the piston comes back down it forces the mixture up through the intake port into the combustion chamber. 

A common problem with the older CR125 2 stroke engine is the main bearing coming out of the race.  This will then allow crankcase oil to be pulled in with the fuel/air mixture.  Really smokes and a lot of oil goes into the exhaust pipe. There is no question if this has happened.

If the lower end is full of fuel your needle and seat isn't seating properly. You have a constant flow of fuel coming out of the carb into the cylinder. The way it works is when the bowl of the carb is full the float raises up and pushes a rubber needle into the hole where the fuel is coming from. If there is dirt or something that can stop it from sealing fuel will comtinue to fill the cylinder. It will leak by trhe rings beacuse they only seal under a load, not whaen sitting still. Your ring are probably OK. You need to clean out the carb.

fuel will leak into the air filter if the float in the carb is not working

This man know's his sh!t, i bought a 250R from him a few months ago, good people.