79 gs1000 petcock/carb help/swap

[wompin]

Ive got at least two of my carbs overflowing out the drain tube. The bike needs full choke to start (it is winter in MN though). Its running super rich even though I have pods and cut-off drag pipes. I just checked float needles, and set float heights to 25mm and still the bowls overflow. Mabye its my petcock? Ill run tests on both petcock and float needles seperately to diagnose.

I am curious if a 1980 petcock will fit my 79 gs1000L.

Will any other carbs, Like CV carbs work with my bike? Carb parts are so spendy I might just try to buy a set of rebuilt carbs if the floats or needles are shot.

Please offer any opinion or advice on this issue.

See the ad here:

http://www.ebay.com/itm/NEW-1980-GS550-GS750-GS850-GS1000-GS1100-PETCOCK-/190758545425?pt=Motorcycles_Parts_Accessories&hash=item2c6a186811&vxp=mtr

Thanks for the help

[tom203]

Take your petcock off and measure bolt centerline spacing- that 80 petcock has 50 mm spacing- hopefully yours is 44 mm, cuz it's a better petcock. Nevertheless, there's something amiss with your float needle seats.
With pods and open exhaust, I'd stay away from CV carbs- so work with what you got and solve the overflowing

[srsupertrap]

Your GS1000 petcock is probably leaking too

[wompin]

running more tests

Ok ill check the petcock bolt spacing later today. That's interesting that you say the 79 petcock is better. Is that because it is opened via vacuum mechanism vs valve? I would have thought a manual shut-off would be more fail-safe. Just curious I suppose.

I will again check the floats, first to see if they are indeed floating, then recheck the heights with carbs inverted and float tabs just touching the float needle (rather than compressing it). Ill do a more thorough inspection of the needles and seats.

Also I will see if my petcock is actually shutting off when there is no vaccum from the motor.

Would faulty float needles and/or a leaky petcock lead to a rich fuel/air mix? My spark plugs are wet and smell like gas, thats why I think its rich.

I checked and I am getting spark on all 4 plugs, plus dialed in points timing as well as I can with no timing gun.

One last thing that has me frazzled: when I can get the bike to run temporarily, the #4 cylinder sends out white smoke from the pipe. I would think that is just condensation since it is so cold here, but why only the #4 cylinder?

Thanks again for the input.

[sedelen]

Contact that E-bay seller in your first post, I was told recently that he has petcocks other than those posted on E-bay. That petcock you found has the wrong spacing.

[wompin]

hmmmm

Thanks for the tip seledeen.

So I just got done testing both my petcock and carb bank, and now I cant reproduce the leak or overflow.

I made a temporary tank out of a bottle and hose, and inserted the hose into the open petcock valve. It held back the full bottle of water. I then sucked on the vaccum hose and it released water. I did this on both reserve and on settings. So the petcock seems to work great. Rule that out as a problem, right?

I then attached the same bottle/hose to the fuel line on my carb bank (off the bike) the water level fell as it filled the bowls, but then it stopped (as it should if the float needles are seating properly). The carbs mysteriously stopped overflowing. Thats wonderful, except whenever I put the carbs back on the bike and fire it up (or try in vain) the bowls overflow.

Would the bouyancy of the float in gas vs water make the difference? Would excessive choke or throttle in attempts to start the bike cause the carbs to overflow, even though they dont overflow per my test?

Please help if you have any ideas

[SqDancerLynn1]

Just go in and replace the carb float needles Around $20 and you should be fine.. Make sure to take the float valve out and clean it too

[wompin]

floats floating?

So, its been a long while since Ive posted here, but Ive got some more issues with my bowls overflowing.

The float needles and seats are clean and there are no signs of wear.

When I isolate the petcock, It works properly and does not leak.

When I isolate the float valve assemblies, they hold back water.

When I test the carb bank off the bike, It does not overflow.

BUT, when everything is buttoned up back on the bike, it ****es gas onto the floor. What gives? (yes I do have the bike held upright and not on the side stand)

The only thing I can think of that is causing my overflow problem is that my floats are not fully closing the gas inlet valve (needle and seat). Mayble the floats are not as bouyant as they should be. They do float, but maybe not well enough.

Does anyone perhaps have a picture of how the floats should look while floating in water for comparison? Id rather be sure what parts are causing my problem before I just blindly replace everything (ie floats, float needle and seat, seat washer, petcock, etc)

[kicker]

Make sure your floats are still buoyant, can you hear any gas swishing around inside them? Submerge them in a cup of gas, are there any bubbles coming out? If no to both then good.
At the very least replace your float needles and seats.

As far as your testing went, water has a higher surface tension than gas so less likely to leak in a situation like that.

[wompin]

Make sure your floats are still buoyant, can you hear any gas swishing around inside them? Submerge them in a cup of gas, are there any bubbles coming out? If no to both then good.
At the very least replace your float needles and seats.

As far as your testing went, water has a higher surface tension than gas so less likely to leak in a situation like that.

Thanks for the tips. Ill be running your tests later this evening, and yes I am now going to break down and just buy some damn float valves. More to come...

[bccap]

Contact that E-bay seller in your first post, I was told recently that he has petcocks other than those posted on E-bay. That petcock you found has the wrong spacing.

He has a website Georgefix.com . Excellent service and prices. I got mine in three days.
Make sure you don't have gas in your oil.

[wompin]

I just checked the site you mentioned and it looks like the poor guy passed away with cancer March 10. There is an obituary on the site.

No worries about the petcock anyways, mine seems to be working well. I am thinking it is the float valves giving me trouble