I have an LTZ 50 I bought new a year ago. I recently changed the oil & plug & noticed a few days later, an oil puddle under it. when I checked it out, everything was tight & the oil smelled of gas. took out the dipstick & it was FULL of gas & oil mixture. any ideas??? Is this a common problem with this machine?

 

This is actually common with most carbureted machines that have a fuel tank higher than the carb. I have seen this a thousand times. Either someone parks the bike without shutting off the fuel or the fuel petcock doesn't shut the fuel off completely. New, used, antique, it happens to them all. I would put fresh oil in it and check to make sure the petcock is functioning properly... replace it if its not.

 

Hi, new to this site but not new to bikes/quads, although I have been away from it for 10 years or so. Just getting back into it with our son.

Being totally humble here, I'd like to ask how a petcock being left open could possibly allow fuel to enter the case of a 4 stroke and how it could possibly cause a big leak?

Are these little quads built different than larger (adult) quads and bikes? Almost sounds like it's being said that the fuel is more gravity fed than fed by applying throttle and wouldn't think that would be true otherwise there would be A LOT of flooding questions.

I just have never encountered a situation where leaving the petcock open has caused any harm at all. Along with a 2005 Suzuki LT50 we also have a CRF50F 4 stroke bike. Never have turned off the petcock on either (other than for storage) and never had any problems.

Interested to learn something here....again, not trying to be a smartalic (sp?) just truely interested in some info.

Thanks.

 

Has the carb been flooding? The majority of times that gas enters the crankcase is when the carb floods, gas makes it's way past the rings(end gap) seeping into the crankcase.

On the newer atv's the fuel petcock works off of vaccum pressure, diaphram allows fuel to enter the carb. when the engine is running.

 

If everything is operating as it should your correct....this should not happen.

Get a little wear or a bit of dirt in your needle/seat in your carb.....the gas will flow right thru the intake and fill the engine.

 

after getting the first reply about the petcock & the carb, I took the carb apart & cleaned it & put it back together. changed the oil & she was good to go. Thank you for the info.

In regards to the other questions, not that I know anything about these things, I did reference the owners manual about the fuel shut off. It has quiet the confusing labeling on the machine. it has an on, & 2 positions labeled "pri". Primary maybe...no. It stands for Prime. To be used in this position to prime the carb only. for situations like running out of gas, so they say. there is no off position. but my quad was left in the pri selection. which would run gas into the carb constantly without restriction. possibly allowing it to flow through the intake & fill the engine.

AGAIN THANKS A MILLION FOR THE INFO!!!!!!!!!!!

 

Thanks for the explinations. Guess I'll start turning off the gas, better safe than sorry.

 

hey cuoffroad. The caburetors on most bikes and atv's are in fact gravity fed. The float valve inside the carb blocks that draining action of the tank and controls the fuel level in the carb. Over time, the weight of the fuel will push past that tiny little needle in the carb. It can overfill the carb, run into the intake, down past the piston, and by springtime your crankcase is dripping fuel/oil on the floor of your shed. There is not many flooding issues because the float is operating normally. If the crankcase is not fuel contaminated but there is excess fuel in the carb, it is quickly used up by the choke/starting procedure and the float level is controlled as usual. The crankcase may not always be overfull but still be contaminated with fuel... sometimes enough to cause the engine to run rich by pulling fumes through the crankcase vent in the airbox. On 2strokes this can cause a wet plug fouling condition. This is less of a problem on machines that have vacuum operated petcocks. That is why they incorporate the vacuum operation in case you forget. A long time ago, I have heard, the manufacturer's used to recomend parking a motorcycle on a centerstand because they believed the float valves would be more prone to seeping when leaning to one side. Modern bikes that are fuel injected have fuel pumps that will support the weight of the fuel and injectors that shut off fuel access to the engine completely and therefore do not require petcocks at all. Machines that have fuel tanks below the level of the carburetors (i.e. Yamaha VMax)require a fuel pump and dont have this flooding problem.

Hope that is a little more clear.

 

hey bmarshall. That is it. the Prime position allows you to flow fuel to the carb without engine vacuum before starting. The petcock you have have is vacuum operated so you would want to return that switch to the ON position once it is running.

 

Correct....but honestly Ive never had to use the PRI position on any of my bikes.

I would just leave it ON at all times unless you need to use the PRI position.