Gas gushing out the back of carbs, float seating issue?


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Jefferson, OR-USA
Thanks, in large part, to help on these boards I have my 1982 Maxim up and running on both cylinders(and it sounds nice and healthy for not being registered since 2000). Problem is it's way too rich and I have gas dripping out the backside of the carbs. I assume it's a float seating issue. The carbs are now off, so I'm ready to adjust whatever needs adjusting.

I have never adjusted floats in my life, so I appreciate any help, videos, online FAQs, etc.

PS- I may have put something together wrong after fully cleaning my carbs or am missing a part (I think PO took carbs apart).

I can post pictures of anything if it will help.
Loook in the manual here on the site about carbs,It should give you break on all the parts and where they go.
Use a guage and measure your float heights 28mm is what they setting for the floats.
The richness could be coming from a number of things,incorrect fuel air mix,wrong jetting.
Your carbs use to different size main jets so maybe you put them in wrong:shrug:
Your chocke may not have been put back in correctly or is not set properly.
Once are sure that your carbs are out together properly do a bench sync,you can find out how to do this on youtube.Once the bike is running well enough then you need to a full sync of the carbs.Theres threads on how to make a cheap manometer for doing this.
Do a search on carb overhauls theres plenty to to read up on.
Thanks, where do I measure from? From the float gasket to the bottom of the float?

I can't seem to find exactly which two points to measure (not in the manual that I have at least). Oh and the manual says 30mm +-1, so is it safer to just set it at 28mm?

My brother actually has a manometer, I just need to get it running better first, I'll check out bench sinking.

Thanks again.

PS- I have my fuel/air mix screws 2.5 turns out, but my jet sizes are unreadable, is there a way to measure them(I kept them in the same carbs I took them out of [seperate boxes], but PO may have mixed them up)?

UPDATE: While looking at the diagram it looks like I have the float needles upside down. I assume this is what would allow gas to pour out the backs of the carbs? Can anyone confirm this?
UPDATE: While looking at the diagram it looks like I have the float needles upside down. I assume this is what would allow gas to pour out the backs of the carbs? Can anyone confirm this?[/QUOTE]

The pointy end goes into the well, and the end with the springy pin sticks out. Yes this would cause fuel to leak badly.
Well, I'm glad it's something simple! Thanks.

Still wouldn't mind checking float height before I put the carbs back in. I think I'll just measure and see whats closest to 30mm and adjust from there.
Check your petcock to make sure it is shutting off the fuel when it isn't running or the gravitational pull on the fuel in the tank will force the float down and it will pour out a small breather in the intake side of the carb I learned this one the hard way just before I joined this site
Fuel overflowing the float bowls can be caused by float level off, bad floats or leaking float valves.
Float height is an easy adjustment. With carbs upside down, measure fro the gasket surface of the carb body, not the gasket. Measure to the top of the float. Different places depending on float type. Brass on the float bulbs, foam on the flat area by the float bulbs.
Foam floats seldom go bad but brass floats can develop leaks and fill with fuel. Test by shaking, do they slosh. You can also submerge them in a cup of warm water and watch for bubbles where the air leaks out.
On the float valves they can be assembled wrong. The springy end goes toward the float. The pointy end goes in the valve seat.
A dirty seat can let fuel leak by the valve. One easy trick is to take a Q-tip, peel off the cotton on one end. Wrap a bit of 4-0 steel wool around the tip. Use this steel wool Q-tip and carb cleaner and spin the tip in the valve seat. This will remove any dirt or burrs.
On some carb the valve seat has a gasket or o-ring that seals it into the body of the carb. Check this for wear.
If it only leaks when you are running the bike I doubt the petcock is the problem. Easy to check though. Unhook the fuel line, run a hose from the petcock to a far. Let it set over night. No fuel should be in the jar. If fuel in the jar rebuild or replace the petcocks.
Thanks everyone for all the info(especially about how to measure!). I got both float needles out and one is completely stuck and the other smells of varathane and doesn't move too well. I found some new ones on ebay for a decent price that are made in Japan, so hopefully this will fix my problem.

I noticed that my filter is empty when in "run" position and only gets fuel when I open the throttle up, so I think my petcock is okay, but I'm gonna try the glass jar thing once I have some better weather to see if it does leak and go from there.

Any tip on how to pull the brass seats out(they're push-in, not screw-in)? I think mine are sealed well, because I can only get them to just barely wiggle and the screens look nice and clear.

I think I have this whole mess figured out (I'm completely new to carburetors, so it's been a learning process). Thanks to all those that participated in this thread, you've all been very helpful.