Hello! I'm new here and I was hoping someone could help me, it is my first bike and would appreciate all the knowledge you guys will give me. I bought a 1981 xs400 special-II last month and have been riding it for the past two weeks. Well today i tried going for a ride, but the bike decided to not stay on even after i turn the idle screw and then it smelled like gas shortly after. I looked down and tada! gas coming out of the left air filter. Also during this time i noticed the left side engine is not really making any sound when i start the bike. The gas would only leak if the engine is on as well. I have the oem petcock. Help?
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Gas leaking out of left air filter when engine is on.
- Thread starter killjoy33
- Start date
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- help xs400 1981 xs400special2
mmmboost
XS400 Enthusiast
This is your needle valve in the carb failing to seal properly when the level of fuel in your bowl should be causing the needle valve to seat and block off fuel supply.
Might be time for some new ones. I didn't remove mine when I cleaned out my carbs, so I can't tell you if there's an o-ring to replace or if the whole thing needs replacing. Someone with a little more XS400 experience will probably chime in with that info.
Might be time for some new ones. I didn't remove mine when I cleaned out my carbs, so I can't tell you if there's an o-ring to replace or if the whole thing needs replacing. Someone with a little more XS400 experience will probably chime in with that info.
Thanks bro! So this is what i need to buy? I plan on opening the carbs later when i get home.
https://www.mikesxs.net/yamaha-xs65...ith-o-ring-oem-3l1-14190-20-25g-14107-20.html
This part?
https://www.mikesxs.net/yamaha-xs65...ith-o-ring-oem-3l1-14190-20-25g-14107-20.html
This part?
mmmboost
XS400 Enthusiast
That's the part, but it looks like there are two styles on MikesXS. There is the kind you showed that looks to slip into a bore and then there looks like there is one that threads in. and has a hex head. From the description it looks like the one you posted is the correct one, but if it was me replacing it, I'd pop off the float bowl just to be sure.
The carbs on my 78 XS400E have the style with the hex.
The carbs on my 78 XS400E have the style with the hex.
Hey so I opened up the carbs and everything looks fine. I did change the spark plugs cause the old ones on the left were jet black compared to the right one. It stopped leaking gas for now. But im worried theres something wrong with the left side of engine
I would make sure the petcock is shutting off when the bike is not running. The stock ones tend to Leak. I would also drain and replace all the oil including the sump to make sure there is no gas left in the motor. When you rebuild the carbs set the floats to the proper height. The float valves are metering devices for the carbs NOT shut off valves for the fuel tank. That's the petcock.
kshansen
XS400 Addict
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Well if the fuel is leaking on the left while running and the plug on the left side is also jet black to me that means it is running rich on the left and if the float valve is not controlling the fuel level like it should that would also cause it to be rich.
Even if this seems to have cured itself for now I would check to see which style float valves your bike has and order a pair to have on when it starts acting up again.
I would not assume that your bike has one or the other style just going by a listing somewhere. Unless you know for a fact that noone has ever touched the carbs since the bike left the factory it is all a guessing game.
I know that my 1988 Sportster looks for all appearances to be stock . But I know that the carb that is on it came off a "Big Twin" Harley. Basically the same carb but this one has an accelerator pump where the original did not have one.
Okay so little update my carb rebuild kit is on its way on monday but i wanted to try and clean the left carb first to see if it would make a difference. I adjusted the brass carb float on the left to match the right and i also cleaned all the jets with carb cleaner and compressed air. Yesterday after doing all those i was able to ride for a couple of hours with no problems. The new spark plugs were just brown and not jet black anymore after that two hour ride. Today I was gonna take it for a ride this morning at around 8AM but it started leaking again. I think theres a problem with my ignition on the left side. Every time i use the electric start early in the morning i notice that the left side is silent, but when i use the kickstarter i can get both sides to go on and there wont be a leak.
When i purchased the bike it was missing the electric start button and the PO told me electric start works but he lost the button. Now im thinking maybe theres a reason why he never replaced the electric start button. Now im fine with kickstart only but early morning(50-60degrees) i have a hard time kickstarting the bike.
My next approach would be wait for the carb rebuild kit(i bought 2) and rebuild left carb. If it still leaks im guessing i should avoid using the electric start. If it doesnt leak im gonna go ahead and change oil cause Ive flooded the air filter 4-5 times already trying to diagnose the problem, im sure theres fuel that got in the engine.
When i purchased the bike it was missing the electric start button and the PO told me electric start works but he lost the button. Now im thinking maybe theres a reason why he never replaced the electric start button. Now im fine with kickstart only but early morning(50-60degrees) i have a hard time kickstarting the bike.
My next approach would be wait for the carb rebuild kit(i bought 2) and rebuild left carb. If it still leaks im guessing i should avoid using the electric start. If it doesnt leak im gonna go ahead and change oil cause Ive flooded the air filter 4-5 times already trying to diagnose the problem, im sure theres fuel that got in the engine.
