Wont stop leaking gas!!!!!!!!!!!

83 midnight maxim 750... Ive cleaned the carbs 5 times. had the carbs on/off 10 times. The bike will start and run and idle. it actually runs pretty well untill it floods out from overflowing carb/carbs. fills up the airbox and leaks out the boot. and of coarse ive had to change the oil 5 times in 20 miles. Ive put in new needle and seats. that made no difference. I have not synched the carbs due to yics tool. I have hooked up a vacuum guage and they were all good. i have the mixture screws about 3 turns out. Ive adjusted the float levels to 17.5mm from bottoms of floats to gasket mating surface where bowl attaches. (no gasket) I have tried 10 different ways to set the floats just to try to stop the problem. They are at 17.5mm now. im not sure im doing it right. anyway..........my petcock lets out fuel all the time on ON. not free flow but dribbles. I bought a rebuild kit for it but not all the parts were right. so at least it dont leak externally anymore. if you turn to PRI it will drain the tank right out my carbs. I have the tank clean using evapo rust. i have a inline filter(clear and clean). Bike idles okay till the damn thing floods. its worse the more fuel is in the tank. bitch of it is when i use a remote bottle on the bench while off the bike it dont seem to leak. so i think i have it fixed. then start, ride, stop, leak, flood, die, waste money on garage floor. what else can do this other than needles and seats? I had a set of mikuni carbs once overflow all the time. it was caused by plugged vent tubes. but these carbs are different and i dont see a vent. Anyone live in illinois that knows these machines? I need to sell the bike but have to fix it first to get what its worth.

 

you have a problem with your float height ... do a search for the clear tube method

 

You have to still have sticking needle valves or your floats are hanging/sticking. Check you floats for easy movement, make sure you have them it right side up. Search on dressing the needle valves and seats - been covered a few times - good practice to dress the surfaces a bit.

Look at the dry float height setting post - a lot of good pics (and a couple of fuzzy ones I put there )

Also a good idea to verify you float heights with the tube as mentioned

 

I read through the posts on float hieght and seat dressing again. Im almost positive im doing it right. I didnt dress the seats but they are brand new. Although its good advice, it didnt seem to fix his problem, and i believe its the same deal. Ill have to pull them again and do the tube test to be certain i guess. what else could it be besides float adj or needle valves not closing. a fully seated needle valve should be able to handle the pressure of a full gas tank even if you left it on PRI all day. Is there a vent on these carbs? when i adjusted the floats, i set them to 17.5mm dry. then even going further, i made sure they were the same hieght when pressed down to close valve. i even made sure they were the same hanging hieght when holding the carb set right side up. they are all the same. ill check again though. why not try to hit the twenty mark for carb removal and install.

 

I'm pullin mine again this weekend, #2 and #3 keep sticking!!! They will be fine for days then Gas on the floor!!!!

 

did you put in aftermarket needle and seats too?

 

yes they are brand new, i have not dressed them with sand paper but i did use the golf tee trick, on my older honda 3 &4 wheelers the seats always had a small bur on the seat hole, a golf tee would knock the bur off. I need to change my oil again. i have never had this much trouble with needles before!!!! I shoulod have left the old ones in, they did not leak!!!

 

mine didnt seem to leak either. well at least not this much. i can drain my tank on the floor and in the oil if i turn the petcock to prime. what did you set the floats at and how? we have the same problem. ive been trying to fix it fo 6 weeks now. maybe we should have sprung for the oem needles and seats????

 

When dry and filling they can tend to stick. snayke62 everything you said is spot on so I would be looking to be sure my floats swing free.

Try this when you have them off and empty of gas. Turn them upside down and blow into the fuel line - you should be able to tell if they are sealing. As you know something obviously has to be catching or not sealing or you wouldn't have your issues.

There is no vent tube as found on some carbs.

 

thanks bill. I was waiting for the vent answer. Well i guess ill grab a beer, and a philleps screwdriver and take them devils off again. ill take a damn picture this time of them and the adjustments. you would think with the rubber tip needles they would seal very easily. but like to say, it must be getting hung up somwheres. i can remove, teardown, re-assemble and install these things in 30 miutes. give or take 2-6 beers........LOL.

 

You seem pretty knowledgeable but did you put the floats in upside down?
On the hitachi's it is easy to do... I did it. That's not saying much tho haha.

Definitely set the floats via clear tube for sure.

 

Have you checked that the fuel tap (petcock) is not leaking through the vaccum line? This will send fuel straight into #2 inlet port and drain back out through the carbs into the airbox / crankcase.

Worth checking out as it seems you've done all the work you should do on the carbs (and you said the problem didn't happen with a remote tank).

Good luck with it.

 

For what its worth I had the same thing going on with the last set of carbs I did. Drove me crazy. Could not get them to seal no matter where I set the floats. Ended up putting a very tin washer on either side of the floats to shim them into the center of the float pin. Also reset the tang that is used as a open stop so that they could not drop to far down and hang up. Set it so the fuel will flow freely but doesn't let the floats drop to the point the needle cocks in the seat. That took care of the "have to tap it with a screw driver on the first fill issue" and my leak problem. I always test them on the bench before I install them on the engine. Level them out and let them sit with fuel on them for a while. Cuts down on the wasted fuel and time.

 

Excellent Idea - this is a good thing to check before you pull them again!

 

You could spend five bucks and get a lawnmower fuel cut-off.
It won't exactly fix your problem, but will keep you from dumping gas in your oil, or making a big mess on your garage floor while you find the real problem.

Your real problem could be the aftermarket needle and seats.
The float pivot pin AND the inside of the rolled metal of the float need to be polished with ultra fine paper.

 

had the same problem someone told me the floats on my 1985 could become soaked in gas after 2hours or 2 days and let the gas leak out.

 

If they had a hole in them that could be true.

 

wingnut325 good tip, i will check how for they go down. I'll try the washer trick too.

 

Aren't these floats some kind of solid, closed cell plastic foam??
Not hollow?
Chacal !!

 

new find!!! my after market petcock is leaking!!!! I have the carbs off and i'm cleaning, boiling in purple power, then rinse in pine sol!! They are going to be Clean!!!