Carb Puking

[four_shot]

On my ride home from work thursday, I stopped at a light. I noticed (as Suki almost spun out from underneath me at takeoff ) that there was a puddle that wasn't there before.

First thing I thought was that I sprouted an oil leak. As I stop at the subsiquent stop sign, I look at the ground and don't see anything. I dont smell oil or the like.

I get home and shut down only to find a fuel puddle evaporating from under the bike.

I fire it off and figure out its coming from the #2 overflow. My first thought is stuck float, (i just cleaned the carbs + cycle orings kit)

I set the petcock to prime and wait, nothing.

I set it back to run and fire it up only to watch it run out like a leaky faucet.

IIRC the petcock draws vacuum off of #2.

So my question is, is this typical of a bad petcock? The only time it leaks is when the engine runs.

Although I'm lucky, I was going to ride back to work on fri but took the cage instead. Halfway to work I got rear-ended!

I loved my car!

 

[Krunk_Kracker]

When you had it off, did you check the float height? When mine was leaking from the vent, it was due to horrible set float height.

 

[BassCliff]

Hi,

The bikes with VM carbs get the vacuum for the petcock from carb #3.

Yes, float height is important. Also see:

[FONT=Trebuchet MS, sans-serif]Overflowing Carbs[/FONT]

I'm sorry to hear about your fender bender. I guess it's a good thing you left the bike in the garage.

Thank you for your indulgence,

BassCliff

 

[four_shot]

I was certain that I set the float heights right... (triple checked)...I guess as soon as I'm finished dealing with recovering the objects that are now "sealed" in my trunk, I'll get the rack off and see what I screwed up.


It gives me an excuse to bench synch them *sigh*

Any ideas as to why it only leaks while the engine is running?

 

[BassCliff]

Hi,

Any ideas as to why it only leaks while the engine is running?

Because that is when the vacuum operated petcock is open. Read the link above. Oh nevermind, I'll just copy and past it here.

Overflowing Carbs by Mr. bwringer

Let me point out the obvious: If a carb (or carbs) are overflowing when the bike is not running, you have TWO problems. First, your petcock should prevent ANY flow; second, the needle valve should allow flow only up to a fixed height in the bowl (ie, not overflow). Excess fuel has to make its way past both of these parts.

(A third possibility on old carbs is for fuel to flow past the inlet seat O-ring. [n/a for VM]. That doesn't apply to newly rebuilt carbs, since the owner has just installed brand new. Right??)

I'm not 100% sure why some needle valves leak and others don't, but I'm starting to lean with Keith Kraus' suggestion, which is to use only OEM valves and seats. Simply because it works. The question why is a separate matter. (I have a theory, but no guinea pig to test it on at present).

For the petcock, you'll hear a number of suggestions. I think that the vacuum operated petcock should be kept operational, for a few safety reasons.

Several of the folks here are convinced that petcock rebuild kits are useless, and your only real option is to buy a new OEM petcock.

For now, for people who are 100% sick of carb overflow & the ensuing problems, the consensus then is to go with OEM petcock, seats & needles. it's expensive, but it seems to be the only certain way to correct this BS once and for all.

(I would add: no doubt there are people whose overflow problems began when they installed carb rebuild kit(s). The machining on the parts is often abhorrent and inexcusably amateurish, and the f&^%#ing O-rings don't fit correctly. The consensus for a while now has been to buy gaskets IF you need them, valve seats & needles IF you need them, and an O-ring kit.)


The petcock does not, in any way, REGULATE the rate of flow. It should be either on or off. If you have overflow on a running bike (and it's not inhaling fuel through the petcock diaphragm via the petcock vacuum line) then there's a problem with the inlet valve.

Either:

1) the float is no longer buoyant enough or is badly adjusted, or

2)the valve is bad, or is being held open by some foreign matter.


Thank you for your indulgence,

BassCliff

 

[refeicul]

one other thing my bike has cv carbs so i dunno if it would be much help. i rebuilt my carbs and set the float heights with in the middle of spec but noticed that there was a bit of fuel on the airbox boots i had to lower my float height to fix this still with in spec just on the "low end" since then no problems even though it wasn't a huge problem like a puddle.. my first instinct is tap a screwdriver handle on the float bowl with the airbox off and see if that fixes it. check the fuel height is 2nd and 3rd would be float height 4th inspect the float "is it warped or bent badly?" 5th needle valve "is it springy?"

 

[four_shot]

I set the petcock to prime and wait, nothing.

This should have had the same effect fuel flow wise as idling the engine, shouldn't it?

The short story is I should probably quit obssesing about it until i get the time to start tinkering.

 

[panda]

HI neighbor, im in mundelein, glad 2 know ur ok

Hi guys, just wanted to say I really appreciate all the info that is found in these forums

and since I have a similar problem I have seen on the forums that the best thing to do is replace the petcock and replace the needle valve if you get fuel leaking when the engine is off .

I have gone to the crc2 site and z1enterprises, both I have found to not be too easy to find exactly what you need or maybe I need 2 get more used to them. Any way could you guys recommend a good petcock and set of needles, links would be EXTREMELY helpful. i have an 80 GS750E, maybe some who is more familiar with Z1 can help me out.

 

[four_shot]

Well, I finally got to the bike yesterday and this morning.

I let it idle in the driveway and went for a short ride yesterday and nothing. No leak.

I did find that the #4 bowl gasket is seeping a little. (It's nothing related I'd think.) The #2 carb drain is also dripping a little (at the screw). If I remember that was the drain o-ring I nicked and ended up reusing the old one.(I wonder if that's my whole issue?)

I still need to get the rack back off for the bench synch. I think I may have time tomorow if PJ lets me breath . I was gonna try to adjust the carbs today but my tach cable is still MIA and my wife took my inductive timing light (with tach function) with her to work in the back of her car. ( It got shifted there because we traded cars when she took mine to the insurance adjuster on fri.)

Thats it in a nut shell, I'm still curious to figure out why it was only leaking while the engine was running and not on prime. I'm riding to work today dancing so we'll see how she holds up. I'm thinking the carb thing was Dave's way of protecting me knowing I wont ride if the bike is acting up.......

P.S. Hi panda! P.M. and we'll see about getting together over the summer.