GS450L blowing oil/gas out of the crankcase vent - HELP

[ironb12s]

Yeh, maybe a little rude, but to the point nonetheless. :-D

Where do you live, CharFord? Is there a Harbor Freight Tools store near you? They have a hand operated vacuum pump that will save you from swallowing whatever you would apply vacuum to orally. :arrow: You can get the MityVac system, or the US General simile, there. Great investment to save you a mouthful of fuel, or bleeding your brakes, the list goes on...

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39522

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92474

[Nessism]

If the petcock is not leaking with the tank off it might be serviceable. You need to suck on the vacuum line to see if there is a leak - once you pull a vacuum it should hold - no bleed down. Of course be careful or you might get a mouthful of gas which won't be fun.

[charford]

Calm down there bwringer, if I have learned anything from working on cars it is that you don't start replacing things until you have diagnosed the problem and ruled out all the options.

I just tested the petcock. In the prime position gas flows freely. In the on and res positions I sucked on the vacuum hose and gas flowed freely out of the gas line but not a single drop came down the vacuum hose. I sucked as hard as I could (until there was a full stream) and still nothing. Does this indicate that there is nothing wrong with the petcock or should I replace it anyways?

Chris

[Nessism]

I just tested the petcock. In the prime position gas flows freely. In the on and res positions I sucked on the vacuum hose and gas flowed freely out of the gas line but not a single drop came down the vacuum hose. I sucked as hard as I could (until there was a full stream) and still nothing. Does this indicate that there is nothing wrong with the petcock or should I replace it anyways?

Chris

If there was any vacuum "bleed down" while sucking on the line I'd replace the petcock, otherwise, you can leave well enough alone.

In support of Brian’s urging, the fuel system is full of rubber parts that deteriorate with time. It’s one of those pay me now or pay me later sort of things. From my experience, for example, I wouldn’t bother even trying to get one of these old GS bikes back on the road (assuming it sat for a while) without doing a complete carb teardown and rebuild with new O-rings. There are endless posts in the Technical forum from people struggling in one way or another to get their bike to run right because of carb problems. Establishing a baseline where by you know for a certainty that the carbs are clean, and the intake boots are sealing, is a clear path forward.

[charford]

Agreed. I just purchased all the carb orings, new intake boots w/ orings, and I went ahead and bought a new petcock because in the end you are right- it is only $50 so you might as well not even think about it. The carb actually looks pretty good and I am really starting to wonder if the intake boots are the problem here.

I should get all this stuff and have it done by thanksgiving- I guess if it is still having problems after that then I need to start thinking about head gaskets. Will update when I finish all this stuff.

Thanks

[edhuhn]

I had a similar problem. 1980 GS450L...It turns out that the float in one of the carbs is bad. (gas inside the float) I could shake the float and hear the gas sloshing around inside it. I did a dye penatrant test and found a lot of hairline cracks in the brass. The gas in the float kept the float to low and the gas level high in the bowl. Now I need to find a new float and put everything back together again.

Ed

[charford]

I was just finishing the carb cleaning and wondering if that could be the problem. I have heard people say that was a problem before. I couldn't see any cracks or anything in the float, and couldn't hear anything in there but it could have drained by now. How do you do a dye penetrant test? I believe they sell floats at bikebandit.com, prosourcemotorsports.com, or any dealer.

Also when I was cleaning the carb everything looked great: however I did notice that the left one was dirtier on the outside than the right one. Also the left one seemed to have more varnish especially around the throttle body- could this tell us anything?

Chris

[bwringer]

I had a similar problem. 1980 GS450L...It turns out that the float in one of the carbs is bad. (gas inside the float) I could shake the float and hear the gas sloshing around inside it. I did a dye penatrant test and found a lot of hairline cracks in the brass. The gas in the float kept the float to low and the gas level high in the bowl. Now I need to find a new float and put everything back together again.

Ed

Brass floats? :shock:



Anyway, you'll probably want to remove the intake boots and examine them -- the problem you're looking for is cracks in the rubber or any separation between the rubber and the aluminum flange. The rubber should be pliable and not too shrunken or hardened. If replacing the carbs is a major all-day operation requiring levers, pry bars, axle grease, and the services of an especially flexible midget, then the boots are probably too shrunken and hardened.

You'll also want to take a look at your airbox -- make sure the lid is present and airtight, make sure the base of the air filter forms a seal, and make sure the boots between the airbox and carbs are in good shape.

These are all just standard things you have to take care of on every GS sooner or later. The intake boots and petcock only last about 20 years, so I think it's well worth getting them out of the way right off the bat. Plus, a leaky petcock can be quite dangerous, so I don't think it's even worth risking.

[bwringer]

Also when I was cleaning the carb everything looked great: however I did notice that the left one was dirtier on the outside than the right one. Also the left one seemed to have more varnish especially around the throttle body- could this tell us anything?

Chris

This is common -- any leakage from the petcock or carbs will end up on the left-hand carb, since it's the lowest when the bike is on the kickstand.

[charford]

I am certain the intake boots need replaced. removing the carb was pretty easy but I think I see a slight crack in one right along the seam. Also, I cant believe I haven't mentioned it yet, but the boot that goes from the airbox to the carbs are completely worthless and 100% shot. It looks like someone couldn't get the carb out before so they took a utility knife to them and they are crap. I guess I just didn't this could have been contributing the problem, but perhaps that is part of it as well.

I plan on just submerging the floats and seeing if any fluid leaks in.

[charford]

Hello all,

just an update in case anyone is still interested. I got a brake bleeder and applied constant pressure to the petcock and it still performed a-ok. I am going to replace it anways but I feel confident ruling that out as the cause of the problem. Completely finished the carb cleaning. Everything looked good but I did have a concern. After I removed the needle valve seat I noticed that one was clogged with crap, and believe it or not there was actually a dead fly in the other one. The screens were clean and everything looked good otherwise. I am not sure if this debris from the tank could have caused any sort of problem. Main jets were clear as well as everything else.

I took the intake boots in the the suzuki dealer and they told me that the boots definitely needed to be replaced, though he said that wouldn't explain the gas in the oil problem- but it may be the cause of the lack of power at half throttle.

I am waiting for all the parts to arrive on Tuesday and I should have this bitch back together and tested.

Thanks

Chris

[bwringer]

The debris explains the gas leaking -- it was holding the float valves open and allowing the float bowls to overflow.

Dead flies are a bit rare -- debris from a deteriorating petcock is more common. :-D Sometimes you also get crud loosened up when someone moves a petcock lever that has been in one position for years.

The mesh filter on a petcock will normally filter out all but the tiniest particles, so this might be missing from yours. So there's one benefit of a new petcock.

The mesh on the petcock is normally all the filter you need, but if the tank is rusty inside, very fine powder-like particles of rust can still get through and cause problems.

Adding a fuel filter can also cause problems -- it's difficult to install these so that there's no kinking or flow restrictions. And it's hard to find a filter that will work better than the fine mesh on the petcock and still flow enough fuel via gravity feed.

[charford]

Alright guys it is time for an update. It is possible that the bike is actually running worse than before.

I have put in a new petcock.
Fully cleaned the carbs.
All new orings in the carb
New air intake boots
New intake boots to the engine w/ new orings
Fresh oil change
New gas

The bike starts and runs, but I am still having some of the same problems. I don't know if there is still fuel in the oil I will have to run it awhile and see. The bike is backfiring alot and the idle speed is sporadic. The idle will speed up and then slow down and then speed up. Sometimes the idle speeds up very fast. Occasionally there will be a fair amount of fuel coming out of the overflow tube on the left side of the carb, especially when the bike idles way down.

Also, the engine/exhaust is smoking alot. I am pretty sure this is just because there is alot of gas and oil on the outside of the engine.

Thoughts anyone?

[TheCafeKid]

I am certain the intake boots need replaced. removing the carb was pretty easy but I think I see a slight crack in one right along the seam. Also, I cant believe I haven't mentioned it yet, but the boot that goes from the airbox to the carbs are completely worthless and 100% shot. It looks like someone couldn't get the carb out before so they took a utility knife to them and they are crap. I guess I just didn't this could have been contributing the problem, but perhaps that is part of it as well.

I plan on just submerging the floats and seeing if any fluid leaks in.

Tripple check your float LEVELS too...if they are set too low youre going to have a problem as you are describing...i just found it in mine. Also, i would advise changing your oil filter too, not just the oil, if you had gas in it.

[TheCafeKid]

Brass floats? :shock:



.

My yammie's both had brass floats in the carbs.