How high can the fuel level in the bowl actually get?

my problem is so bad and has been happening for so long I actually think it's a Good thing since I can put my finger on the exact question I need to ask.

So I did a complete rebuild on my carbs and the motor would run ok and then not, and everytime i removed and put the carbs back on it would be something different. I actually found the most stability after replacing the airbox to carb boots and filling a small airbox crack with funtak (that stuff to hang posters).

But the problem of gas getting into the cranckcase on the 2nd or 3rd day after things are going well has been haunting me. fuel levels are great. So the bike sat for a week because of some iginition problem. I've proved the float needle valves OK by leaving the carbs on the bench and gastank above with the petcock on Prime and no leak. But the freaky thing is I did a quick clear tube check and the fuel level was 1/2" above the bottom venturi lip! not to mention when I pulled the carbs about 8 0z's of gas came out of the #1 & #4 intake boots

So I'm guessing the problem is a stuck float in the Down position or a stuck needle - but the needle moves very nicely in the tube, and the float also seems to move very nice on the hinged pin. I remember reading something about someone puting washers on the both sides of their float ends. would that help?

Thanks guys

 

Are you sure the offending float or floats don't have a HOLE in them so that after a while they fill with gas and quit floating?

 

No! so I guess I could keep them submerged with a wrench in a cup of gas and check later on...

 

it does happen, it's not that obscure...

 

The Material in the Float is Solid, Buoyant, and Non-porous. They Float.
Really early Carbs had Brass Floats that were soldered together that COULD suffer a solder fracture and SINK.

The thing to do.
Put in a SHUTOFF Valve.
You can get a good one at the Hardware Store for $8.00.
Briggs & Stratton -- Plastic.
When you are going to leave the Bike for awhile ... Shut-off the Flow to the Carbs.
It's a Easy-Fix for a problem that might be a Leaking-By Petcock or Leaking or Stuck Floats.

 

So the float can't fill with gas? I had one that looked like something small borrowed in it, and replaced it, but I did noticed that while one bubble would surface when submerging it, there wouldn't be any sloshing sound when shaking it, as the Haynes manual suggested!

 

Thanks Rick, but one thing - If the floats were getting stuck a little, the fuel could still get into the case over bumps correct? or maybe I just need to turn Off the Shutoff valve after each time i shut the bike

 

The shut-off valve that Rick speaks of is an inline one, like those used on small engines. You would have to splice it in. The petcock does not have an off...the on position needs a vacuum signal to open but if it fails it can let gas flow without that signal.

 

Let's clarify something here: A stuck or improperly seated float is only half the equation for gas in the oil. The fuel has to KEEP coming, which means the petcock ISN'T holding back fuel like it should. "ON" and "RES" are vacuum-operated; "PRI" is on all the time. Unless you've been leaving it on PRI you have more than just a float issue.

My apologies. I assumed all the floats were hollow; I'm sure the ones in at least one set of Mikuni's I've been into had hollow plastic floats. (The brass ones are a real hoot, my Norton has those.)

 

I thought the same thing a while back. First I had heard of solid floats - only ones I had seen before were hollow. Oh well.

 

okok, thing is, I can keep the petcock on Prime for days with both tank and carbs on bench and the valves won't leak (tank above carbs). And the fuel levels will be good.

I rode the bike a few times and when I shut the bike and tried to start it several hours later it went in hydro lock for a reason, probably #1 or 4 was full of fuel. Then I moved accross country to NY and when I removed the carbs the boots were completely full, it was a joke.

Note: I remember when I was adjuting the twang last month i moved it to a point where it pinched the hinge pin and I need to pull it back and articulate the screwdrivers in order to bend it at a slightly different access pint or fulcrum... And the clear tube method last night put the fuel waaaaay above the bottom lip of the venturi, BUT IT WASN'T LEAKING!
Extremely close to giving up because I know no one will give up a set of working carbs for cheap, but I am willing to trade some carb guru, afterall, my carbs were rebuild by this shadetree mechanic and i'm usually not this dumb.

I'll take your comments as the last and then it's to the classifides section

thanks again guys, whatever happens this is fun. I guess I will try the sandpaper thing on the hinge pin and pollishing paste in the valve tube

 

You need to insure that the Floats are going to to operate without any issue that might cause them to stick or not work exactly as they are supposed to do.

Short of buying Rebuild Kits you have the following option.

Float Hinge Pins; re-finish.
Chuck them in a drill and spin them fast.
Hold some 800 Finishing Paper to them and get them refinished.
Don't forget to do the end chucked in the drill.

Float Valve Bodies; refinish.
Roll-up a piece of 1200 Finishing Paper until it will fit tight in the Float Valve Bore.
Twist the Sandpaper around and shine the Inside Bore of that Float Valve Body.
Look at the sandpaper after you withdraw it.
Cut-off the end at the tarnish line and continue using it on the others.

Float
Run a drill through the Inside Diameter of the Cylindrical Surround that wraps around the Float Hinge Pin.
Don't enlarge it. But, remove any build-up in there that would cause the Floats to not be 100% free in their movement.

Get a Manual and review the Chapter on adjusting Float Heights.
Set the Float Heights to specs and see if it's OK.

Any problems after doing refinishing will mean getting new parts if they still hang-up!

 

thanks Rick, that's happening today, i'll post the results in a few days

 

From what you posted, I don't think your floats are set properly either.

Use the clear tube method to check the float levels.
They sould be 2 mm +/- 1mm from the line where the bowl meets the bottom of the carb body.

1/2 in from some other point is not likely to be correct. You only have a 3mm range.

If the floats are set properly and seating like they should, a possible petcock would be a non issue.

 

i had the same problem for a little while, just adjust your float level down, if its fine after that, theres your problem, if not, clean your seats out. there could be something small stopping it from closing all the way.

 

EERRRRRRRRRRRRRRR after re-adjusting the #1 fuel level for whatever unknown reason it became bad in 2 weeks, it just doesn't look like the float travel is enough, it's probably 1mm of movement before the needle seats, and the twang is pointed pretty high up to achieve the good level. think I'm going to take a video of the travel on post a link, it just don't look right.

Started the bike and it runs like absolute crap, throttle input is not possible and the idle increases if you pull the #3 plug wire! I initially pulled the plug wire cause that header was cool, bike was running great for ONE day and I haven't touched the other carbs this weekend, just that #1.

btw, the float hinge didn't need the drill bit cleaning method, there is even a little play when the pin in it. the sandpaper did a great job cleaning the needle tube though. before the cleaning I didn't see any sticking after inspection. I even think the needles were replaced because they look real good. I guess if the new needles were shorter than stock the twang would need to be up higher

 

I love it, Monday morning and everyone's Back Online

Anyway, here's a bump to the Gods

 

There is a tab that sits against the post that limits how far the float drops - perhaps yours is bent too far? Most of mine are broken off.

 

thanks Bill, I know they're all there but I guess it's worth inspecting.

I'm pretty much on my 4th month of working on this bike and have had the premise of well, if it actually ran good one day and acts different everytime I take the carbs off and put them back on, it can't be the top end. then a few beers this weekend told me that maybe it is. Maybe take off the valve covers and see if a rocker is loose or something.

That's basically where I'm at. My bike is pretty nice and I'm into it for about 1100 bucks and I'm getting upset cause I see alot of other well running bikes for the same price.

WHO CAN I SHIP MY CARBS TOO? I'm almost choked up about it. From what I've learned here my carbs look great, I don't know what else to say

thanks ya'll