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Hi, I have a 1989 DT125 which was having running problems. When the bike runs it seems to flood itself and fuel pours into the crankcase from the engine. the carb has been cleaned and overhauled and is spotless.
Hello
if im showing the right diagram. the carb on your bike as an oring that seals off the float valve seat. i would pull it out and inspect it. another little trick is to hook up fuel to the carb with the float bowl off and push up on the float and ensure that it is sealing. cause this very much does sound like fuel is bypassing the float valve assembly. really that is the only way you are getting fuel into the crankcase. and also is consistent with it running so rich. hope this helps. thank you.
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Its probably the crankcase vent. The carbs have more than likely been pouring gas inside the motor,to the point of overfilling the crankcase oil with gasoline. Drain the oil and change the filter. And while youre draing it,..look inside the carb bodies,and see if gas is still running into the cylinders.If it is,then your float height is not set correctly..(too high)...or the needle valves need to be replaced. (valve that hooks onto the floats).
loose wires seem to be a big thing with these bikes wiring diagrames is available online try google images if i get chance il add a link later
as for fuel problem turn the fuel tap to 3 oclock position prime constant fuel feed if you get it running this way turn tap on position down
most people including myself have had problems with bike only running on 2 cylinders usually 1 + 4 ive cleaned the carbs fully and replaced coils and leads + plugs also cleaned every connection and made them tighter with pliers etc to all wires under the tank as on my bike was all gummed up oil + corrosion etc bike now runs alot better
Your carb has a hung float or needle and seat issues.
You have to take the carb off the bike and consider replacing the float and/or needle and seat.
You might get by just raising the float level. But this is only a stopgap maneuver. Buy a new float!
You bike is flooding so it wont run right until this is fixed.
The reason its only flooding while its running is because your bike has an automatic gas tank valve that opens when the bike starts and makes vacuum that opens the valve. It is saving you from the bike totally filling up with fuel!
Sounds like one of the needle and seat assemblies in the carbs is stuck open and is flooding the cylinder which then floods the crankcase...
ALWAYS turn the fuel tap off when engine is not running.
Take it to a bike shop, they should be able to fix it a short time.
sounds like the floats are stuck. cleaning carbs should do the trick. its a good practice to start up motorcycles and let them warm up from time to time while being stored.
With the oil problem I read on another site that Yamaha did that so that excess oil would be burned up in normal running (but this was usually smaller amounts). Anyways they disconnected the tube going to the air cleaner and had tied up in such a way that any excess oil would land on the chain thus lubricating it. But if you have that much oil coming out it could be that you have put in too much.
It seems likely that your fuel pump is not operating, you should hear the fuel pump priming when you turn on the ignition, if not the fuel pump is at fault, this is not uncommon and a replacement is the answer.
hook up all the vacuum lines - yes or cover/plug all
to stop fuel flow - hooking up all the vacuum lines or covering/plugging them would be technically correct but will not stop the flooding/fuel overflow;
run correctly - with constant overflow/flooding, it will not run correctly.
To my knowledge, overflow could only be caused by:
faulty valve pins, worn out rounded pyramids, necked/indentations on the surface of the rounded pyramid, cracks (rubber type);
worn out inlet port;
dirt, sand, foreign object lodged against inlet port hole;
mis-adjusted floats;
Which would mean, go to do it all over again.
Just a start, do postback how things turned up or should you need additional information. Good luck and Thank you for using FixYa.
Wait... fuel is pouring out of the crankcase breather? Are you sure it's not the carb overflow tube? The crankcase breather should be going back into your airbox or through some kind of filter.
If gas is coming out of there DO NOT START YOUR BIKE. It means that gas has gone from the tank through the carbs into the cylinder and is now in your oil. Thinned out oil is the devil for bikes.
Sounds like you'll need to clean the carbs and set the float bowl height and maybe rebuild the petcock. Check to see if any fuel is coming out when the petcock is turned off. If it only has on pri and reserve then check for gas in the vaccum tube.,,
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