2007-07-22 18:00:30 · 7 answers · asked by motorcyclecrazy 2 in Cars & Transportation ➔ Motorcycles
Gas is leaking from a vent tube on top of left magneto cover. When the bike is running, gas is coming out of this tube at full force, if you just kick the bike over, it spews out this tube. Is it just the needle in carb sticking? or worse internal seals. No gas is coming out of the bowl over flow.
2007-07-23 08:41:10 · update #1
M/C,,,Your question sounds a bit odd.
Which "left side cover",exactly?
Yamaha usually bundles all their vent tubes together,
then routes them down the back of the the engine.
At this age,however,it's not unusual to see them separate & routed who-knows-where.
If all the hoses are still bundled and/or in approx original position>exiting at back of engine,,,
It's real easy to confuse which hose comes from where.
My curiosity is that there is only ONE vent tube which even remotely can be described as coming from "Left Side Cover".
Thats the Magneto Cover on left side of engine.
It's Very RARE to happen,,,but it IS possible for Fuel to come out of that vent.
When it does,,,,it's a Serious Problem.
Crank seal failure Plus certain other conditions CAN cause Fuel to come out the Vent.
The Magneto cavity has No Pressure or vacuum,,the VENT is merely to allow condensation to escape.
On engines which have flooded their crankcase due to leaking Carbs,,,,which are then kicked-over to try to start them,,
They will sometimes blow the Crank Seals out of the seats.
And fill the Mag Cover with that excess fuel.
An engine which gets a sudden & Large Gulp of water will often do similar thing to Crank Seals.
Thereafter,,,the Crankcase Pressure communicates with the area supposed to be isolated by the seal.
On Primary side,,,Right Side,,,Transmission gets filled with Fuel.
But it's vent never "overflows" cuz of several reasons.
The Magneto Side,,Left Side Cover,,,,it doesn't actually "FILL" then sit there and overflow,,,Not in most instances.
IT CAN,,,if fuel leaks thru Carb Long enough,,and seal is blown -out bad enough to allow gravity feed.
But it would take 1/2 gallon of fuel or more.
Usually it just partially fills the cover,,,then when trying to start it,the Spinning Flywheel sligs it up toward the Vent Hole,,,and the leaking Crankcase Pressure then forces it out the Vent Tube.
It's a RARE Occurence,,but it DOES Happen.
Anytime I hear such as "Fuel Smell/Leak,etc from Trans/Cluch/Mag/Crankcase area",,,such as "Left Side Cover",,,,it always raises a flag concerning lower end seal integrity.
I've had about maybe a 8 or 10 over the years which had
"Fuel leaking from Engine Mounts".....
so Fuel from "Left Side Cover" is NOT as weird as it gets :)
.........................................................
Vast majority of fuel leaks are due to carb float valve problems.
The carb on your bike has 2 "vent tubes"
*Lower/Center/Rear ON the carb's float bowl is FUEL OVERFLOW
*Right side of carb body is float BOWL AIR VENT
Fuel will overflow out of Bowl Overflow Hose which is attatched to Lower rear side of Carb's float bowl.
You Most Likely are seeing the Carb Overflow tube,,from Lower/rear of Carb's float bowl.
If You determine that gas Really,Actually IS coming from ANY other hose,,,then you have other problems.
...........................................................
There's a total of 4 "Breather/Vent" on those engines.
On ENGINE itself:
1)Right Side of engine,just behind cylinder is TRANSMISSION VENT
2)LEFT side of engine on top of Magneto Cover is Magneto Vent
On CARB itself:
3)On Right side of Carb,,,Fuel Bowl Air Vent
4)On Lower Rear of Carb ,,,Fuel Overflow tube
The only other 2 vent hoses on the entire bike is on the Oil Tank ,,it's supposed to be clear plastic.
And the Battery vent,also clear plastic.
...................................................
No intent to alarm you about the fuel leak,
But DO verify actual origin of the Leaking vent hose.
Most likely it's a Carb Overflow hose,,,and just mistaken as coming from the L/H Cover vent.
If it IS really coming from the left side cover,,,Ya need to fix that also.
Keeping in mind that it's a SECOND problem,,in addition to any possible actual Carb Leak.
Carb Flooding CAN cause a Crank Seal Problem behind magneto,,in the L/H Cover.
Or,,,that seal can just fail on it's own.
Good Luck with it,,,hope it's just a simple case of mistaken identity of the Hose.
2007-07-23 07:07:38 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Trace the tube to it's source. If it connects to the carb it is the overflow for the bowl. If so your float needle is not sealing. It is either worn at taper and should be replaced, sticking and needs to be cleaned, or the floats have sunk (not likely). Floats rarely need adjusting if they haven't been "messed with." If the fuel leaks with the petcock in the "off" position it is leaking too.
After a few emails and more details from motorcyclecrazy it sounds like the fuel leak and crank seal problem detailed by txm42 below. You guys know what you're talking about too. Isn't this great!
2007-07-22 19:26:53 · answer #2 · answered by bbentlaw 2 · 1⤊ 1⤋
That's a breather tube for the flywheel magneto, to prevent over heating from the points.
The left side crankshaft seal is leaking, blowing fuel from the bottom end into the cover.
Remove the cover and start the bike to see the fuel being blown out, for conformation.
2007-07-23 10:11:12 · answer #3 · answered by guardrailjim 7 · 1⤊ 0⤋
I just sent a truck load of Colon-Blow to the Yahoo Corporate HQ. That should clean them out. Someone want to donate a truck of TP to aid in the clean up?
2016-05-20 22:58:13 · answer #4 · answered by temeka 3 · 0⤊ 0⤋
Iassume you mean the carb? if that's the case just bad seals and if you mean the gas tank it is building to much pressure
2007-07-22 18:05:15 · answer #5 · answered by Anonymous · 1⤊ 1⤋
listen to bbentlaw he kows what he's talking about
2007-07-23 03:48:13 · answer #6 · answered by suzukifox01 2 · 0⤊ 1⤋
your float is needing adjusting
2007-07-22 18:07:32 · answer #7 · answered by superkack2000 2 · 1⤊ 1⤋