Leaking gas from airbox...

[Guest]

I bought a 1981 GS750E 2 weeks ago and it ran perfect until yesterday. I filled the tank with gas from a different gas station than the previous 2 tanks, and it ran great the rest of that day but when I started it the next morning it ran rough and sounded like it was missing on a cylinder. Upon closer inspection I noticed a slow gas drip from the airbox where the #4 carb joins it. I pulled the plug on the #4 cylinder and it was fouled. I cleaned the plug thoroughly and checked for spark. Good spark so I put the plug back in and started it. It ran rough but I thought if I took a short ride it would clear up. Well it didn't get better and stalled on me whenever I attempted to idle. I read quite a few posts about bad petcocks and stuck floats but thought I'd try for some advice before doing any more work. Any suggestions are appreciated!

[tom203]

Follow link to Basscliff's site and read up on the proper way to clean carbs. Sounds like that carb float is not sealing- might be dirt - and might be worse. Try tapping on #4 carb and see if that helps. Remember, it's 30 years old and bound to need maintenance, no matter how hard the PO tried to avoid it!

[Redman]

Some comments:

- look see if you also have gas in the oil.

- have not left the petcock on PRIme have you?

- like others said, maybe a carb float stuck.

Again, welcome to GSR.

.

[Cafe650]

Just thought id drop a line because im having a similar and dont seem to be finding alot of info about it or maybe im not searchign right might just start my own thread in order to save confusion but will also watch this one, my #1 carb suddenly started leaking gas out of the boot where it connects to the airbox also and my #1 plug smells a bit of gas and is much darker then other 3 plugs. However my difference is that I have no issue running or idleing just curios to see what your problem ends up being.

[tom203]

Just thought id drop a line because im having a similar and dont seem to be finding alot of info about it or maybe im not searchign right might just start my own thread in order to save confusion but will also watch this one, my #1 carb suddenly started leaking gas out of the boot where it connects to the airbox also and my #1 plug smells a bit of gas and is much darker then other 3 plugs. However my difference is that I have no issue running or idleing just curios to see what your problem ends up being.

Hmmm... no running issues, but leaking gas and fouling plug? Maybe you should reconsider- four cylinder bikes work best with all four cylinders happy! Have you done the dreaded deed- remove and properly cleaned the carbs?

[Cafe650]

Hmmm... no running issues, but leaking gas and fouling plug? Maybe you should reconsider- four cylinder bikes work best with all four cylinders happy! Have you done the dreaded deed- remove and properly cleaned the carbs?

Seriously as crazie as it sounds it runs great no dead spots chugging flooding nothing. Smooth accel well as a smooth idle, and yes i know a 4cyl is happy with all 4 running the way they should, thats why im so puzzled I changed plugs about oh maybe 300 miles ago now at that time all plugs were same color and no fouling, I did have an issue where the bike would leak a bit of gas out drain tube on idle and drop idle and alomst die id rev it up and it would clear up for 30 sec or so then idle down again however that was takin care of by simply sealing my stock airbox idle cleared up stopped leaking gas, now this new issue has developed a few hundred miles after the fix its a very minor leak but its still a leak where there should be no gas at all. Also yes Ive had the carbs cleaned after It developed a leak between carbs last fall I brought them into the local Suzuki shop and had them gone through and clean them wich i might add was very over priced 300 bucks to do what i coulda done for price of a couple O rings and carb cleaner and a few hours of time, but at the time didnt know anything about these synced carbs figured id let the pros handle it <---- dumb. Think I shoudl pullem and clean again myself? OR do i have somethign more going on local mechanic mentioned Valve could be pulling gas back through but sounded odd to me. And i apologize to cryptid I do not by any means mean to take away form your question. but figure maybeboth our issues could be same thing and play the 2 bird with 1 stone method.

[BassCliff]

Greetings and Salutations!!

Hi Mr. cryptid,

Sorry I missed your earlier posts. Let's get you properly welcomed.

But first, have a look at this article: Overflowing Carbs.

Anyway, to get you started, let me point you in the right direction, dump a TON if information on you, and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[spyug]

Same issue right now with rebuilt carbs on my 750. I didn't change the o-rings on the needle valve unit so I'm guesstimating that's my issue.

As we keep saying ( and I keep forgetting or ignoring) there is no quick and dirty way of doing the cleaning. Do it right or don't do it. Fully strip, dip in proper cleaning fluid, rebuild with new o-rings, bench synch then synch when running with a manometer. No other way friends.

Good luck and post some pics.

cheers,
spyug

[cryptid]

Update: I did leave the petcock on prime by accident....new to the GS and thought it was off. I read up on the petcock and I understand now that there is no "off" position. I ran 2 tanks of 91 octane with 10% ethanol, and it was fine, but the 3rd tank I filled up with 91-no ethanol. Could the ethanol have loosened up some varnish and the non-ethanol carried it to the carbs? I will definitely take the carbs off and complete the full clean and rebuild but I don't have time right now and the bike is my only mode of transportation. I bought new plugs today; NGK D8EA, and I am going to change the plugs tonight. Hopefully that helps. I noticed that the gas leaks for about 30 seconds to a minute after I turn the engine off but not while it is sitting, not running.

[cryptid]

Thanks for the welcome and all the info, Basscliff! This forum and the GS Resources has been more than helpful!

[BassCliff]

Hi,

See to your gasoline leak. Gas will leak into the cylinders and cause hydro-lock and bend a rod when you try to start. Or it will leak past the rings and into the crankcase, diluting the oil, ruining bearings and such.


Thank you for your indulgence,

BassCliff

[tom203]

Seriously as crazie as it sounds it runs great no dead spots chugging flooding nothing. Smooth accel well as a smooth idle, and yes i know a 4cyl is happy with all 4 running the way they should, thats why im so puzzled I changed plugs about oh maybe 300 miles ago now at that time all plugs were same color and no fouling, I did have an issue where the bike would leak a bit of gas out drain tube on idle and drop idle and alomst die id rev it up and it would clear up for 30 sec or so then idle down again however that was takin care of by simply sealing my stock airbox idle cleared up stopped leaking gas, now this new issue has developed a few hundred miles after the fix its a very minor leak but its still a leak where there should be no gas at all. Also yes Ive had the carbs cleaned after It developed a leak between carbs last fall I brought them into the local Suzuki shop and had them gone through and clean them wich i might add was very over priced 300 bucks to do what i coulda done for price of a couple O rings and carb cleaner and a few hours of time, but at the time didnt know anything about these synced carbs figured id let the pros handle it <---- dumb. Think I shoudl pullem and clean again myself? OR do i have somethign more going on local mechanic mentioned Valve could be pulling gas back through but sounded odd to me. And i apologize to cryptid I do not by any means mean to take away form your question. but figure maybeboth our issues could be same thing and play the 2 bird with 1 stone method.

Sealing up airbox is unlikely to stop a gas leak- sounds like one of your float valves was and still is leaking .Running above idle (when engine starts using more fuel) the leaking is not a problem, but at idle , fuel is overflowing this float valve and getting to airbox, probably accumulating over time. Yes, a dealer carb cleaning is expensive ( and maybe iffy) and that what's fantastic about this site- folks offering real world advice and it's free! I think I run it some more before I pulled carbs- maybe, maybe it will stop or lessen- but keep checking.

[Cafe650]

Sealing up airbox is unlikely to stop a gas leak- sounds like one of your float valves was and still is leaking .Running above idle (when engine starts using more fuel) the leaking is not a problem, but at idle , fuel is overflowing this float valve and getting to airbox, probably accumulating over time. Yes, a dealer carb cleaning is expensive ( and maybe iffy) and that what's fantastic about this site- folks offering real world advice and it's free! I think I run it some more before I pulled carbs- maybe, maybe it will stop or lessen- but keep checking.

How about running a can of Seafoam through her is that safe in these bikes or does that cause more problems then fix? What are peoples opinions about using it? Ive had quite a bit of exp over the years with small engines owned 4-wheelers, dirt bikes, go carts, lawn mowers, 3cyl snowmobiles, and such but motorcycles with these 4cyl and 4 carb setups are very new to me and not sure what kinda additives if any are safe for these engines.

[tom203]

How about running a can of Seafoam through her is that safe in these bikes or does that cause more problems then fix? What are peoples opinions about using it? Ive had quite a bit of exp over the years with small engines owned 4-wheelers, dirt bikes, go carts, lawn mowers, 3cyl snowmobiles, and such but motorcycles with these 4cyl and 4 carb setups are very new to me and not sure what kinda additives if any are safe for these engines.

I already recommended using Seafoam once this month for another poster- I don't want to be a shill for Seafoam! Just joking!! Sure, for $10 it's worth a shot, but it usually works on clogged passages or pilot jets, not as a stop leak product. It won't hurt anything. After spending $300 on professional carb cleaning, I'd be annoyed at this problem. Run it some more, try a different brand of gas, etc. Kept clean and using stock setup, these carbs seem to run well even after 30 plus years- as far as I can tell my carbs have never been off and they still behave nicely.

[Larry D]

Before you run the bike again.....1. Get the petcock problem fixed and 2. Change the oil and filter, run for a hundred miles or so and change it again.

Gas in your crankcase is not a good thing.