Bike leaking?

[davidpabst]

Hey guys,
I have a problem with my bike. It's a 1993 750. When i start it, everything seems fine, but after like 20 seconds on idle, the bike begins leaking and the engine stops. It leaks by a rubber line under the bike. I really don't know where that line comes from..
My bike was working fine before. The only thing i dad recently was to remove and re-install the fuel tank to do some maintenance...
Any clues!?

Thanks a lot!
David

[gsxkat1100]

I guess its leaking fuel?

Check the float heights and needles and seats.

[TRPUT]

Work out what it's leaking and where it's leaking from. Trace the rubber tube up ... it could be coming from the battery, air box or fuel tank over-flow. There's also a chance you have mixed up some hoses while the tank was off. Pull the tank again. Check everything is connected properly. Advise which hose is leaking. A couple of photos might help.

[J///Kidd]

I can think of (4) lines running down to the bottom of the bike.

1 is the battery vent tube (attaches to the battery).
1 is the fuel tank vent (overflow) tube (attaches to a metal nipple on the bottom of the fuel tank).
1 is the fuel level sending unit vent tube (attaches to fuel level sending unit on bottom of tank).
1 is the air box drain tube (attaches to the bottom of the air box).

I'd lift the tank up again and make sure all your connections/tubes are still good. You may just be noticing in trickling down the tube but in reality, it could be coming from somewhere else and just using the tube to drip down (ie. may not be coming from INSIDE the tube but dripping down the OUTSIDE of the tube). Trace the line it is leaking from to see if you can discover the source. If it wasn't doing this before you removed the tank, you can bet you did something while removing the tank to cause this so hopefully you won't have to pull the carbs.

[gsxkat1100]

[QUOTE=davidpabst;2330472]
It leaks by a rubber line under the bike. QUOTE]


.... I did not see that..... I guess I'm just used to seeing carb overflow posts.


Yeah, I would pull the tank off and check the lines like everyone else said.

[davidpabst]

So i finally checker, and the line leaking is the one from the bottom of the air filtre box. When i start it, it starts leaking after 15-20 seconds...at the beggining i thought it was fuel because it smelled, but it's oil...
Any clues?

[92xjunker]

Over filled, fuel in the oil, viscosity to thin, bad rings..... there should be a plug in that hose. Some oil is normal, a lot is not.

[davidpabst]

When it leaks, it seems like fuel, but after a couple of hours, the fuel has evaporated and then it's just oil..
Some fuel (a lot) gets in the air box by the rubber hose at the top of the box, the one connected on the rectangular shape on the top of the cylinders.

And the hose has a plug, but it has a hole in it. But anyways, i dont think it's normal that fuel gets in the air box...

I had a battery problem 2 weeks ago, and i tried a lot to start it. Maybe all the unburned fuel just went down in the oil, and now my oil is too thin?

[92xjunker]

Your carbs are over filling, draining into the air box and mixing with the oil residue. Check your float needles as stated above.

[davidpabst]

But the oil/gas mixture is not coming from the carbs, it's coming from the breather, wich is connected at the top of the air box.

So would this be right?
I tried to start the engine and let it on prime for too long, so gas have leaked through the bottom of the engine, in the oil. Then, when i start the engine, the breather takes out the excess of fuel/oil and spits it in the air box, then the airbox gets full and leak on the ground by the hose.
And my oil level window seems all full, it's not at the good level like it was before.
SO i guess a good oil and filter change would do the job?

[92xjunker]

I'll repeat, your float needles are leaking, prime doesn't matter if your float needles are sealing as they should. Change the oil and filter, inspect the needles, Buy 4 rebuild kits and replace the rubber also, this will also eliminate seals that are not sealing.

[davidpabst]

So finally, my problem was in the oil. When i dumped it, i had more than 8 liters of gas/oil, so as soon as i cranked the bike, the oil breather would spit it out. So moral of the story, i wont ever try to start my bike with too much prime or leave it open for a night by mistake!

[maniac1886]

If you carbs are flooding, fuel will come up through the emulsion tubes, and down into your head, as the valves open, they gulp gas down. The gas then slides down around the piston rings and into the crankcase. The longer you let it do it, the more and more that gets in the case. Once you overfill your crankcase, and thin the oil out to the viscosity of water (because of the gas) the oil pretty much goes anywhere it can to escape. Thus, its pouring out of the top crank case vent. Check your oil level with the bike standing straight up, smell the oil for fuel. If thats the case ( and it definitely sounds like it to me, its a common issue) then you need to pull, clean, inspect, your carbs as well as float heights, float needles, any rubber o rings you come across, sync your carbs, and change your oil.

Missed your last post. Since that is the case, you need to get them carbs in order. Check out Carbs 101 in the Wiki. Get them cleaned, make sure the float needles are nice and clean and the float height is within spec. Then inspect the o rings around the float assembly. Make sure they seat well and seal. After you clean and inspect your carbs, bench sync them, then use a manometer to fine tune the sync. You may want to fill them with gas on the workbench to avoid dumping gas into your fresh oil. If they hold fuel on the bench, they should on the bike.

Leaving it on prime shouldnt necesarily make a difference. There has been some back and forth on here that it can make a difference leaving it on prime but if everything is in working order, it shouldnt matter. Either way... Prolly bad practice to do so.

[rk97]

Glad it's been sorted.

I was convinced there was a kinked hose under the tank somewhere that was causing vacuum or overflow issues.

I literally just had my tank off last night, so I was labeling everything with tape to be sure it goes back together the right way :P