GT250 - large amount of fluid in both exhausts

[finkrandy]

Hi and thanks for your help. I recently acquired a 75 GT250 with 1300 miles. Great looking bike but will not run. It tries to run but only if I drain the exhaust, yes you heard that correctly, tilt the bike forward and back to empty it. I get a large amount of black fluid coming from both exhausts. If I rock the bike on the center stand it will drain out. The bike will run for about 30 seconds and then of course there is too much fluid. What can cause this much fluid being pushed through the exhaust? I'm a 4 stroke person so having a 2-stroke is new to me. Thanks again.

[karl pa]

Welcome to the forum.
Does the fluid have a gas smell? do you have drain plugs under the crank to drain the engine crankcase? some do and some don't. If you do I would drain the crankcase and see what comes out.
Do you notice if the gearbox oil level is going down? The 75 and older 250 oils the center main bearing with gearbox oil, if the center crank seals are bad it will put gearbox oil through the engine.

[finkrandy]

Thank you very much. I will check what you suggested.

[jabcb]

As a new member, we have no idea what you mechanic skill level is. Knowing that would help us provide more useful explanations.

The stock petcock is vacuum operated. Had a stock petcock on a 73 GT250 go bad. The bike didn’t get much use & the leak accumulated to the point gas started dripping out of the exhaust.
The carb needle valves do a good job of controlling fuel flow on a running bike but they can leak a smidgen when not running. That smidgen can add up to a lot if the bike sits for a while.

If you have a stock petcock, make sure you understand the three settings: “on”, “reserve” & “prime”. Check to see if it leaks on “on” or “reserve”. Fix or replace the petcock if it leaks.
If you have a manual aftermarket petcock, check to see if it leaks.

A carb could have a stuck float that is causing the motor to flood. The GT250 has “plastic” floats, so I think sunken floats are unlikely. Sunken floats occurs when the float has a small hole & fills up with gas. (Am not sure what the float is actually made out of.)
If you didn’t have a leaking petcock, or the petcock wasn’t left in an always-flow position, then the carbs need serviced.

The carbs probably need servicing irrespective of this issue unless you know enough of the history to be sure they are ok, but you might be able to get the bike to run without carb service if the petcock was the issue.

Use a flashlight to check the transmission oil level with the bike on the center stand. You should see oil. Let us know what oil level you see.

This deals with why the motor is flooding.
You also need to get some of that flooding out of the exhaust & motor bottom end.

[karl pa]

A word of caution !!!!
At this point you should be very cautious starting the engine, if the bottom end is filling with gas or oil and you start the engine, you can have hydro lock and bend and break things.
Another issue could be, on some of my bikes, the check valves leak a small amount into the crankcase, if the bike sits for a long time it can accumulate and as you turn the engine over it works the 2 stroke oil out of the engine and into the exhaust. The easiest way to clear this is to pull the drain plugs, you can also remove the spark plugs and spin the engine over, put rags over the heads because it is a mess when the fluid comes out the spark plug holes.

[finkrandy]

Thank you again