Question about Yamaha RD 350 Motorcycles

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I think my 83 350ypvs is sucking fuel into the crankcase and wont start after ive had it running a while the right hand carb leaks fuel after too.ive changed the carb and fuel leaks out that one too.

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You probably have a leaky intake valve, as the piston sucks air in, it pushes some out through the leak in the intake valve, eventually making the carb leak

Posted on Mar 23, 2011


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IT is likely that the carb is leaking fuel and filling the crankcase with fuel. Causing excessive crankcase pressure forcing oil into airbox through the crankcase vent. Check your crankcase for fuel and/ or being overfilled. If fuel is present fix the carb first, then drain and refill crankcase. After all is fixed run the unit outside for a few minutes and let it burn off excess smoke.

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Weed trimmer starts and then dies repeatedly

Yes this could be the cause of the problem, it sounds like a fueling issue, fuel/air mix. Is fuel getting into the cylinder or can it be seen leaking out between the carb and the cylinder.?

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Trying to find a vacuum leak on a 2005 Nissan altima 2.5s they said on the right hand side of the engine

Best way to find a vacum leak is to start the engine and then spray Carb cleaner in the area you think the leak is in. then put the "tube" on the spray end of the carb spray so you can pin point the leak. The engine should speed up as the carb spray is sucked into the leak.

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Ok, i recently purchased a DTR 125 R 2000 model with running problems The bike will start with the choke on, then die with the choke off, the fuel/air mixture screw was mashed up so i purchased another...

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1 Answer

Right hand cylinder on my rd200 not firing properly, the bike will run, starts perfect, exhaust gets warm on right hand side but no power to ride, any ideas?. have put in new spark plugs, leads and caps,...

Assuming you properly cleaned the carburetor low speed circuit.check the list below.
1.Check the compression on the right hand cylinder.
2.check your points,pull the point cover off start the bike and watch the points if you see bright sparks at the contact point the condenser is is bad.
3.If your constantly getting an oil fouled plug the right hand crankshaft seal is leaking transmission oil into the crankcase.
4.check your fuel flow from that line to that carb.
Hope this helps you determine whats going.

Jun 04, 2010 | Yamaha RD 250 Motorcycles

1 Answer


Two cycle engines must have a completely sealed crankcase to work properly. When the crankcase is sealed, the air to fuel ratio is set by the carb to optimize the operation of the engine. You can try the carb adjustments, I'd suggest backing out (counter clockwise) the high speed jet, if it has one. If not, it's a fixed jet and you'll have to disassemble the carb to clean it. If your engine on runs best with the choke on - the air to fuel ratio is messed. In other words, either you have a restriction in the carb preventing the engine from inhaling enough fuel and you're using the choke to get the right air to fuel mixture OR by restricting the air intake (putting the choke on) your engine is getting its air needs from some other place, such as a leaking seal or gasket in the crankcase. If you run the engine like his for long, you run the risk of burning up the cylinder and making a boat anchor out of the unit. A two cycle mechanic would do a pressure test on the crankcase to check for air leaks. If you're not able to have someone pressure check the engine, your best bet is to look for loose screws on the cylinder/crankcase - and to make sure the fuel delivery system (fuel filter in the tank, fuel line, and carb diaphragms) is in proper condition - replace the filter if dirty, fuel lines if mushy, and put in a carb kit. If that doesn't fix it, you've likely got an air leak that's going to require a mechanic with the proper test plates to find and fix.

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'87 dodge raider wont ilde.

My 88 raider did the same thing. As long as I had my foot on the gas pedal it would run but if I lifted off the gas it would die. It ended up being a vacuum line. I can't remember which one (possibly the AAP) but not sure. I did replace the AAP diaphragm and all of my vacuum lines.

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hi you got an air leak its the air flow not the fuel that controls the speed too much fuel will cause flooding it wont start because its sucking air and eventually when it does the extra air being sucked in causes it to accelrate you need to lift your bonnet listen for signs of air being sucked in it may be a hose , or inlet manifold gaskets carb gasket it might even be the carb as it will have rubber seals diaphrams i had the mixture jet come out before and the car takes off like a rocket yates210456

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