Suzuki 2 Strokes

Listed on eBay for Suzuki GS850 and other GS models with BS carbs. Will it work unmodified on my 76 GT750 to check float/ fuel level?

Probably. If it fits other size BS carbs, it should fit your BS40s. Those carbs have a larger drain screw than most slide carbs and I can't tell from that photo how large that adapter is. It looks right though.

Of course the carbs have to come off the bike to check fuel level.

That looks to be the same as the float level tool I got from Z1Enterprises. It has 6mm threads.

Per Partzilla, your drain plug is unique to the GT750 CV carbs & the gasket is 8.2mm x 14mm x 1mm.
So unfortunately the answer looks to be no.

But don’t let that stop you. Check to see what threads you drain plug has. Then Google “hose fittings” for that thread, you should see lots of different fittings. You should be able to find one that will work.

I contacted the ebay supplier and they say that the adapter is only 5mm. So JABCB is right. It will not work on a BS40 carb.

I think I know someone who could machine a few of the right size if that might be of interest.

Thanks tz. I’ll return them once received then as I have all kinds of tubing. I took off one of the carb bowl bolts from a spare set I have but haven’t measured it yet. Do you know the size needed in mm? I could go the route that jab cb suggested- what kind of price could a set of 3 be machined for? I’d be interested if not cost prohibitive.

Searched Amazon for “metric barb fitting m8” and got lots of interesting possibilities for reasonable $$.

It is for sure M8?

You only need one fitting but it would certainly be more efficient to check all three at once. I just check one and then drain fuel , remove float bowl and adjust. Rinse and repeat and then move to #2 carb and so on.

Yes. I just measured a drain bolt to be sure. M8 x 1.00 mm pitch.

What I use is a special banjo bolt that I had machined and I feed it though a spare oil pump feed banjo which is the right size.

That’s great info! Can checking float level can be performed with banked carbs off bike benched if they are set to position at same angle as on bike? And if so, am I looking for about 2mm level in clear hose just below the top edge of float bowl? I’ll order up some M8 x 1.00 thread pitch barb fittings.

I’ve used the fuel level tool on a number of VM carbs. After setting the float level, the fuel level was fine for all but 2 carbs (I think), which were off by quite a bit.
The carbs on the two stroke twins are tilted forward quite a bit. They should be horizontal when using the tool. I use a PVC drain pipe fitting that is the right diameter to support the float bowl by the corners.

Have no experience with CV carbs. I hadn’t thought about checking the GT750 CV carbs with them tilted as they are installed on the bike. But I’ve seen info for doing that on the GS-series four strokes.

Take the rack and mount it so it's horizontal and set all fuel levels to 2-4mm below the gasket surface. All should be the same.

I have experience setting levels this way too with VM carbs but this is my first set of CV carbs in well over 30 years. I thought I had float levels correct with the special tool bought from Baz but it was evident when I attempted start up something was wrong and over fueling. New OEM float needles/ seats too! After I pull the carb bank off (easy since airbox is not mounted yet, I will get my mity vac out and suction out each cylinder so not to risk hydro lock. I ordered 3 vertical fittings off Amazon that are 8M x 1.0 thread pitch to 5/32” barb end. I also found the fittings much cheaper (significantly) on eBay from the UK so I ordered 3 sets to make some up to sell later on. Thanks for the help guys- much appreciated!

Jabcb- can you post up a pic of your PVC carb holder stand? I fabbed up a crude wooden stand that should work but may want to build a nicer one. Does yours catch and contain the gas after checking level?

No fab work required. I use a 3” PVC-DWV pipe coupling. Its used for waste water plumbing in houses. This pics shows a VM float bowl for my GT550 cafe project sitting on the fitting.
GT550_FloatBowl_1105 by jabcb, on Flickr

Take a float bowl or the measurements to HomeDepot/Lowes/etc & see if you find something that works with the GT750 CV carbs.

That is clever! I’m going to do as you suggested by taking a float bowl with me to Lowes.