float adjustment?

[Eddie]

I have a 74 gt750, I have been through the carbs in the past,(not recently) and I have set the floats to what the book calls for and my left cyl. has always smoked more, then I started noticing that the over flow tubes (the left and middle) weep small amounts of fuel but very small, and I think its when im riding because I have not noticed it leaking when sitting, although it might im not sure. I rebuilt the carbs with I think the keyster kit,, and I read recently that the adjustments might be different? does this sound like a float adjustment issue or something else? I think its the float adjustment but I measured all of them exactly and with the gaskets on, now im wondering is it possible to just take the float bowl of the left carb without taking all of them of? I haven't looked at it in a while but im pretty sure I can , so im thinking of just taking the left float bowl off and readjusting to see what happens? I really hate to take them all off. I have done it so many times in the past im just getting lazy,, I have the factory airbox on it and im just getting lazy,, so maybe wrong float adjustment? I thought it might just be dirty and need a cleaning but the last time I cleaned them it did the same thing but now the overflow tubes have small amounts of fuel at the end of them and the left one might have a single drop come out but I never see It when it does, is this normal?

[Coyote]

I'd say your carbs are overfull by the thickness of the gasket. I have a Suzuki late model carb manual and it spells it out. NO GASKET when setting the float height. This applies to both the BS and VM carbs. This is a Suzuki publication, not someone's opinion.

[Eddie]

Thanks , it's kinda funny because I have a clymer book and a Suzuki book that both contradict each other , one says with gasket and one says without gasket , I ended up doing it with the gasket I believe ? Can't remember now it's been to long , so I'm thinking they all have to come off to check , I'll probably put it off a little while then check , want to ride a little before I start taking stuff apart , plus I need to get new throttle cables so I might as well wait till they come in , Damn it

[Coyote]

This book came out when they switched to gang mounted carbs. It's called GT380/550/750 New Type Carburetor Service Manual. The book actually has a part number. 99522-01030-01E
Don't feel bad. Every time I flip my GS1000 on prime, it dumps fuel all over the floor. Been through the floats and needles 3 times and it still does it. It stops as soon as the bike starts and begins to vibrate so it's either a stuck float or a stuck needle. When I open them up, everything is free moving and the needles seat just fine..Never have figured it out. Oh the joy.

[Glyn.G]

I'm not sure but I would of thought that if the float heights were measured with the gaskets in place there would actually be less fuel in the bowls when the shut off valve actuates. I've tried both ways and I still get a small amount out of the overflow pipes. I once taped a small plastic bottle to each overflow pipe and went for a good run out to check how much fuel was actually leaking out. The amount was so small I just tucked the pipes away from the line of the rear wheel and said "sod it".

[yeadon_m]

+1 on what Glynn said! done with the gasket, the fuel height in the bowl will be lower.
Mike

[markush]

Hi!

Yes, but it is given a tolerance of +/- 1mm, so it should not matter whether measured with or without (0.5mm-)gasket .
The setting should be identical for all three carburetors.

I recently controlled the real fuel level at a GT380 using transparent hoses, mounted in place of the float bowl drain plug.
The setting by Suzukis method was the same for all three, and OK.
But: the real fuel levels differed by 6 mm between the carburetors. One was OK, one tended to overflow sometimes, one was much to low.
This is due to slightly different weights of floats and slightly different (or worn) float needle valves.
Maybe too, once a float was resoldered, therefore a bit heavier.

The fuel level should be approximately in the height of heads of the float bowl screws.


bye
Markus

[ConnerVT]

+1 to Markus on everything he wrote.

[jabcb]

Another +1 on that tip.

That looks like a really useful tip for checking float levels on something like a GS-series 4 cylinder, which can be a real PIA to get the carbs off & back on.

[markush]

...GS-series 4 cylinder, which can be a real PIA to get the carbs off & back on.

I can tell you exactly what it is at the 3-carbs-rack.
But you wouldn't want to hear it.

[Coyote]

I get it. I get it. My world has always been upside down.. The external tube method only holds true if everything is perfectly level. Tipping even slightly in ANY direction = all bets are off. So where are we really? Most carbs don't even mount level to begin with. I think they call this bench racing

[Eddie]

thanks for all the info, I do like the clear tube method, pretty nifty , I totally forgot about that, I used to know people that did that years ago, but the last carbs I messed with are from my superhawk, very easy to adjust, just take the bowl off with the gas shut off and look but the gt750 carbs are way more complicated. The left over flow tube on mine drips more than the other two so there must be something going on in there, or this is an accumulation of dripping over the past two years that I just noticed , the bike ran good except for the excessive smoke from the left pipe,, the last time I rebuilt the carbs I did not replace the fuel line that connects them it was on there when I bought the bike, then I started thinking that if its cheap fuel line it might be degrading from todays fuels (I have seen this happen 1st hand) and it might be clogging stuff up in that carb,, guess ill take it apart in a couple of weeks and ill update you guys. I rebuilt a 351 Cleveland about 12 years ago and I bought "good" fuel line from autozone, and in about 2 months the car started running weird, after checking everything I finally took the carb off and there was black pieces of fuel line in it! I checked the fuel line and it had just started breaking down, I ended buying earls blue fuel line and never had a problem again. That's when I started learning about todays fuels, pissed me off,,,,,since then I have been working on a 454 chevy and just make sure I buy good fuel line ,, Coyote I actually found that same book you mentioned , I have that and a Clymer book and both tell you different , and to be honest I cant remember now which way I measured I will make sure to measure it with and without the gasket to see which way I had it set,,i appreciate everybodys help very much thanks guys!!!!!! by the way how do I post pics? It doesn't let me , and I forgot what was said last time, damn im forgetting a lot lately .....and to clarify so with gasket fuel is lower or higher? seems the gasket would make the bowl farther away from the carb body so would that mean more fuel? but then if you measure the float and carb body the way the books say it seems like without the gasket that would put the float closing later , letting more fuel in, and with the gasket it would close earlier? I worked a long shift and cant seem to concentrate right now, think ill go to bed ..

[Vintageman]

I recently controlled the real fuel level at a GT380 using transparent hoses, mounted in place of the float bowl drain plug.

can you tell us what those parts are part# or where you get that wonderful stuff to check the fuel level externally

[markush]

can you tell us what those parts are

The thread of the drain plugs is M6x0,75.
You have to find hose fittings with this thread in your country.

I got mine from a Net-shop in germany which sells steam model engineering accessories.
http://www.dampfmodellbau-keifler.de
go to "Verbinder" in the left menu.
part No.: 14-2025/2
hose No.: 14-2036/3

I forgot to mention. Although it is self-evident: In the method shown, the carburetors must be in the normal installation position respectively have the appropriate inclination.

[Eddie]

ok, I looked at the video that you can get for the carbs, found it on youtube, it says if your using mikuni needle and seat the measurement is 27.60 mm which is 1.08 inches, and if you use a after market needle valve for the float the measurement is 26.00mm or 1.02 inches,,, so stock is 1.08 and after market is 1.02 for the measurement so correct me if im wrong but this is less than the width of a finger nail !? right ,, this is absolutely nothing unless im measuring wrong or my vernier caliper is off or its been that long since I have measured with it, I seriously might be reading it wrong but that looks like nothing at all ? am I wrong???? I used an aftermarket kit not mikuni so I set the floats at the 1.08 and not the 1.02 would this make that much of a difference ? I have not taken the carbs off yet but I know I set them to the stock setting....just wondering if you guys go by what the video says or just go by the stock setting no matter what kit you use? and also the video says to use the gasket?? just throwing that I there .....