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Gas in crankcase, im at my wits end

  • Thread starter Thread starter thewarthog
  • Start date Start date
T

thewarthog

Guest
1982 GS1100G , bike had been sitting a little under a year before I bought it, owner stated he would come out and start it once a week or so. Bike had been cafe'd, chopped to a one seater, Dynojet stage 3 jetting, K&N pods, vance and hines 4 into 1. It had seen better days, didnt idle right and popped a little when testing it, but drove and shifted smooth and and I got it at a price. All new fluids, rebuilt the carbs, NGK plugs, rebuilt the petcock. Had an issue with gas getting in crank before (when checking the view port and smelling the gas cap) and thought I had the problem fixed as everything was running pretty good other than that. I rebuilt the petcock and thought that fixed the gas issue and later when I realized it was still happening, I replaced#1 float needle gasket as gas was overflowing out of that carb when hooking the carbs up to a auxillary tank off the bike.

Still seems to be happening, im out of ideas. Ive taken the carbs apart and changed out the f$#in oil and filter more times than i care to mention, replaced floats, needles, checked float levels. I have the air screws above each carb at about 2.5 turns out which she seems to like, but again I can tell gas is slowly getting into the crank, I think is when I ride rather then when it sits given how slow it seems to be happening but i could be wrong.

Any help is greatly appreciated. Im starting to miss by old GS850 that was more stock and hadnt been so molested
 
Rebuilding petcocks has a low success rate. Lots of disaster stories here on GSR. That's where I would look first. There is a guy on ebay called Georgefix that sells them reasonably if he has your model in stock......
 
Roger that, thank you sir. I remember I was going to do that rather than rebuilding it in the first place but Z1 enterprises (which alot of people recommend on here) was all out of stock on their reproduction petcocks so i just bought the kit. I'll look into Georgefix, thank you again.
 
but, if the carbs are overflowing with an auxiliary tank then the problem is in the carb bowls-the needle, the needle's seat, the floats...
- a rusty tank and no tank filter?...drain a glass jar of gas from tank and see what settles.
- you've done this:
replaced floats, needles, checked float levels
Click to expand...
but how about the seats of the float-needles? and...any chance your float is getting hung up in the carb...maybe the gasket...people have had this on occasion...
-turning the carb upside down and blowing through fuel inlet gives a pretty good indication of the obvious flaws...it takes a pretty good blow to move good needles from good seats.
- also ideally your auxiliary tank should be no higher than the top of where your gas tank would be. IE: if you hang it from the rafters, the "column" of gas may overcome what your float needles can hold back.

Rebuilds of petcocks...well,maybe iffy, maybe not but one thing; if the diaphragm was any good at all, gas can't be getting down the vacuum line to the carb that is connected to it...but it's easy to check if it is
 
The tank is rusty but have an in line fuel filter. The floats all jiggle and bounce real good off the needles but I have only replaced one of the float needle gaskets (the #1 carb) when it was overflowing. I replaced one or 2 floats and needles that didnt move so well but since doing that they all seem to move freely and not rest too much on their respective needles.. I Shoulda just replaced all of the float needle gaskets last time I changed it on the #1 carb to rule that issue out for all of them (guess Im going back in). Also before replacing the float needle gasket on the the #1 carb it would leak while on the bike (when in prime) so im not sure it was the height of the aux tank when i took it off later to try to replicate the issue.
 
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What about the "seats" though? ...the float needles seal against the seats.Mikuni CV carb seats are replaceble but I've got a different carb that is basically garbage because someone touched a tool up into it and gouged it. (and even all the massaging I do with valvegrind compound has not worked...)
 
Ahhh, ok when i go in there i'll get a good flashlight take them out and check out how they look.
 
In order for gas to get into the crankcase, you have to have TWO failures. :-k
1. The petcock has to leak.
2. A float assembly in a carb has to leak.

Both of those items will normally stop gas flow. EITHER of those items will normally stop gas flow. BOTH of them have to fail to allow gas to flow.

For some reason, the success rate of petcock rebuilding seems to be about 10-15%. (Some day, I'll try to figure out why that is so low.) This will be easy to check, just route a hose from the petcock to a jar, observe the results after a couple of hours or even overnight. Even better, route two hoses into two jars, you will be able to tell whether the discharge is coming from the fuel port or the vacuum port. If there is no discharge, your petcock is working fine, you should have no problem with gas getting into the crankcase.

Since you have to have TWO failures to get gas into the crankcase, you know that at least one carb is allowing gas past the float valve. There are two paths it can follow in each carb. One is the obvious one, past the needle and seat, the other is past a faulty o-ring that seals the seat assembly to the carb body. When you "rebuilt the carbs", did you replace those o-rings? It's not all that expensive to replace needle/seat assemblies, might be worth it to just change them all.
dunno.gif


.
 
Steve said:
When you "rebuilt the carbs", did you replace those o-rings? It's not all that expensive to replace needle/seat assemblies, might be worth it to just change them all.
dunno.gif


.
Click to expand...

Yea im kicking myself because I had enough new ones to replace all the o rings last time i took the carbs off. well ive messed with the carbs enough that it only takes like 5 minutes to get them off so f$%k it here we go again. Gonna try the method you mentioned first running lines into a jar for a little while.
 
QUOTE
In order for gas to get into the crankcase, you have to have TWO failures. :-k
1. The petcock has to leak.
2. A float assembly in a carb has to leak.
ENDQUOTE

which is true.

Another true situation can be if the following TWO situations occur at same time

1. Misunderstand the positions of the petcock and then leave it in the PRIme position (lever pointed to rear covering up the PRI lettering)
2. A float assembly in a carb has to leak. (Slight leak that is otherwise not a problem)

.
 
i was going to suggest adding an in-line shutoff valve, but that is bypassing a prob.
 
How i test petcocks:

Put some vacuum hose on each nipple and run each one into its own bottle. Be sure petcock is in the ON position and let it set a day or two....look in each bottle. If theres gas in any bottle you know its a fail and you know what side of the petcock has gone south. If no gas the problem is not with the petcock.
 
Gorminrider said:
What about the "seats" though? ...the float needles seal against the seats.Mikuni CV carb seats are replaceble but I've got a different carb that is basically garbage because someone touched a tool up into it and gouged it. (and even all the massaging I do with valvegrind compound has not worked...)
Click to expand...
I have the carbs off the bike and just looked at the #1 carb seat and like you said one of the sides looks like it was scraped with a tool. Some of the others had some scrapes here and there I'm just not sure if this is the reason as I discovered the #3 and #4 o rings for the needle asseblies were toast and may be the culprit. Fastforward to now, all float assembly o rings are now new and seat as they should and I greased each a little bit cause I aint playin games this time lol.

Some of the floats needed some adjustment in regards to height and this time I had a digital caliper so they are all nicely around 22.5mm within the standards of the manual (with gasket out)

I have the tank off and im doing the petcock test and its been a few hours with no gas leaking out of the gas or vacum line, will keep it like this overnight and check again in the morning but im hoping my previous petcock rebuild is holding.

Will keep you posted, thank you all for your input, will update soon when can test it out.
 
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Bingo, thats exactly what was going on before replacing with fresh "juicy" o rings, good video, thank you!

Edit: I'm getting everything buttoned back up I just was waiting on a new oil filter to finish my oil change, the old stuff reeked of gas obviously. I ran some fresh oil through the bike (not running as i still have the carbs and tank off at the moment) and let that sorta just dribble out the drain plug area over night and cleaned the oil filter housing area real good. New filter comes today so I plan on taking her out for a ride later today. Will update.
 
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Things seem to be working as they should, gonna keep an eye on the oil level but looks like we're in business.
 
bccap said:
I had a little look on Ebay. Couldn't find Georgefix but I did find this. I don't know anything about the seller but he does have a good feedback rating and the price is good......
https://www.ebay.com/itm/Suzuki-Pet...h=item520d4471c4:g:03oAAOSwDFNWFXo8:rk:7:pf:0
Click to expand...


Yea I think im gonna bite the bullet and get a new petcock, I still think its happening slowly and at least getting a new one will help narrow it down if that still isnt the cause. I see georgefix on ebay has some in stock now. pulling the trigger
 
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