'85 FJ1100 setting fire to itself, spewing oil(?) from gearbox(?)

[ScavengerProd]

So, my friends FJ1100 set fire to itself earlier this season when I was supposed to help him change the oil. We fired up the engine to heat the oil, but it puked out liquids and subsequently set fire to itself. Happily we extinguished the fire before any real damage occurred. Fast forward to today, we now know where the fluid is coming from, but no idea why and how to fix it.

The liquid came from the airbox, so we thought it was fuel being dumped out of the carbs somehow, possibly by a stuck floater. Banging on the carbs didn't do anything for what would later be obvious reasons. We finally got the airbox out by tilting the subframe and started the engine to see what was going on. Apparently there's some sort of vent(?) pointing up into the airbox just above the clutch / gearbox. I assume it's oil, but it's very watery for cold oil, and also it foams. Please see attached images and link to a short video. The video is short due to fear of fire. Sorry for vague explanation or if this has been posted before as I have no idea what that thing is called nor its function.

Help?

Link to a shared video on OneDrive:
https://1drv.ms/v/s!ApQFnnYwqCtNtTl2nCwhTLITOv-I

[FJmonkey]

The engine case is full of fuel. Drain the oil NOW. Then continue your trouble sorting. 

[ScavengerProd]

Alright, thanks. How would it get there when the bike has not been in use for the winter? As in, how to stop this from happening again? Also, out of curiosity, what is the purpose of that.. thing?

[FJmonkey]

That thing puking stuff is the case vent. It allows vapors from the case to escape. Normally into the intake of the carbs when an air box is installed. If the carbs leak, the fuel can trickle down into the cylinders then into the case. If the engine started it could possibly cause a hydro lock and bend/break internal stuff. Very happy you prevented a thermal loss of the FJ...

[ScavengerProd]

Right. Thanks so much again. Now I know where to start: replace oil, fix carbs.

[Pat Conlon]

While the tank is off and you're cleaning out the carbs (be sure to replace the float needle seat o rings) also Check the fuel tank petcock. Make sure it's not dripping fuel. If it's dripping fuel, order a new petcock from RPM
http://rpmracingca.com/proddetail.asp?prod=M%2FC%3A36Y-24500-01

Get this carb kit from RPM: http://rpmracingca.com/proddetail.asp?prod=carbkit
You will be happy you did.

Yes, RPM ships to Norway

[red]

ScavengerProd,

The carburetor floats should stop fuel from leaking into the engine oil.  The vacuum petcock also should stop fuel from leaking into the engine oil.  You have two failures there, and one of them is fairly recent.  Do NOT run the engine before at least one of those two problems are repaired, and the oil has been changed.  Randy at RPM will have what you need.

[ScavengerProd]

Thanks for your input. The petcock was the first thing we checked, and it seems fine. It was already safety-wired, but we re-did it anyway. So we're back to the carbs. Is it likely that the carbs are the cause for leaking fuel into the engine oil when the bike has been standing for several months?

Also, how realistic is it for us to manage to overhaul the carbs sufficiently and sync them on our own? I've done maintenance on my bike for several years, but never something like this.

Yeah, already ordered some stuff for my FJ1200 from RPM, it's difficult not just to buy everything they have...

[balky1]

Thanks for your input. The petcock was the first thing we checked, and it seems fine. It was already safety-wired, but we re-did it anyway. So we're back to the carbs. Is it likely that the carbs are the cause for leaking fuel into the engine oil when the bike has been standing for several months?

Also, how realistic is it for us to manage to overhaul the carbs sufficiently and sync them on our own? I've done maintenance on my bike for several years, but never something like this.

Yeah, already ordered some stuff for my FJ1200 from RPM, it's difficult not just to buy everything they have...

Petcock is the first thing that needs to be leaking in order to get that amount of fuel into the crankcase. It would be wise to rebuild it (change all the rubber parts of it) or get the new one. So if petcock leaks and the float needles in the carbs don't shut the fuel off properly, there is a high chance you will get a flooded engine. Also I wander if the bike was sitting outside disassembled? Then rain could have got in the crankcase via that breather if the hose was disconnected.
It is no problem to clean and sync your carbs. Well, most of the time. Beware not to strip any of the jets or other screws. You will need the gauges to fine sync them on the bike. Before putting them on you need to bench sync them. Plenty of reading material here about everything. Use Google to search this forum by adding "fjowners.com" in the search term. This built in search bar is a bit wacky.
While you are here, take this poll: http://www.fjowners.com/index.php?topic=16984.msg171315#msg171315 It has nothing to do with the current problem, but you will need one of those in the future for sure if you have a stock swing arm.

[ScavengerProd]

The petcock seemed quite ok, and when we were troubleshooting it we couldn't see any leaks at all, but definitely a good idea to rebuild it. The bike was stored under cover in a warm garage.

I got a new piece of information today though. My friend said the he found the bike tipped over resting on a sidecase while he was storing it. So almost horizontal (maybe he should have mentioned that before...). He has no idea how long it had lain there, but at least for a significant amount of time. Could that be the cause?

We replaced the oil and filter today, and we're going to disconnect the spark plugs, turn over the engine, and replace the oil and filter again and hope most of the fuel is gone from the engine. Then we're going to start it and see if anything happens: looking at the petcock and carbs for leaks. Sound good? I just want to double-check the steps we're doing as this is new territory for me.

Thanks for the hint, I know there's a lot of info about rebuilding the carbs, was just wondering if it's feasible for someone with limited experience with carbs.

[oldktmdude]

   Make sure that you have the petcock in the run position and not the prime position. Fuel should not flow to the carbs in the run position unless the engine is running.
Regards, Pete.

[aviationfred]

I got a new piece of information today though. My friend said the he found the bike tipped over resting on a sidecase while he was storing it. So almost horizontal (maybe he should have mentioned that before...). He has no idea how long it had lain there, but at least for a significant amount of time. Could that be the cause?

This is a very important bit of information. and very well could be the cause of the fuel inside the crankcase. CV carbs do not like to be tipped over, they do tend to leak and cause major concerns for fire. My guess with this added info that there is nothing wrong with the petcock or the carbs.



Fred

[balky1]

I got a new piece of information today though. My friend said the he found the bike tipped over resting on a sidecase while he was storing it. So almost horizontal (maybe he should have mentioned that before...). He has no idea how long it had lain there, but at least for a significant amount of time. Could that be the cause?

This is a very important bit of information. and very well could be the cause of the fuel inside the crankcase. CV carbs do not like to be tipped over, they do tend to leak and cause major concerns for fire. My guess with this added info that there is nothing wrong with the petcock or the carbs.



Fred

Yeah, probably not.
Just a side note: put the petcock on ON or RUN (I can't remember what it says) while it is mounted on a tank with enough gas and you shouldn't see it leaking. Then try to suck on the hose that connects to the intake manifold and you should see it pouring out and when you stop sucking it should stop. It is good to check it when you got everything in pieces. If you got your carb rack off the bike, empty them up, turn upside down and try to blow in the hose that connects to the petcock, i.e. fuel hose. You shouldn't be able to blow air inside since the needles should be stoping it (considering you cleaned everything before that and no gunk is blocking the passageway). If you can, one or more needles and/or O-rings need replacing (do all four at the same time).

[ScavengerProd]

This is a very important bit of information. and very well could be the cause of the fuel inside the crankcase. CV carbs do not like to be tipped over, they do tend to leak and cause major concerns for fire. My guess with this added info that there is nothing wrong with the petcock or the carbs.

Yeah, I thought so too. Hopefully that is the case.

Just a side note: put the petcock on ON or RUN (I can't remember what it says) while it is mounted on a tank with enough gas and you shouldn't see it leaking. Then try to suck on the hose that connects to the intake manifold and you should see it pouring out and when you stop sucking it should stop. It is good to check it when you got everything in pieces.

I think we actually did that a while back as an initial troubleshoot, but thanks for reminding me.

If you got your carb rack off the bike, empty them up, turn upside down and try to blow in the hose that connects to the petcock, i.e. fuel hose. You shouldn't be able to blow air inside since the needles should be stoping it (considering you cleaned everything before that and no gunk is blocking the passageway). If you can, one or more needles and/or O-rings need replacing (do all four at the same time).

The rack is still mounted, buy I assume that when the airbox is off, it'll be pretty obvious if the carbs are dumping fuel, or am I wrong? Again, thanks for the tip, will keep it in mind if the issue doesn't resolve itself.

We're planning to get this done the day after tomorrow, thanks again for all the help.

[balky1]

Probably it will. You can check it with carbs on the bike by pouring the fuel in the line. There shouldn't be any leaks from the hoses (i.e. overflow hoses and choke circuit hoses) when you fill them up.