T500M float height - measure from where?

frappy · Post by **frappy** » Mon Jan 26, 2009 12:47 am

Does anyone know if I measure the 27.3mm for my T500M from the clean base where the float bowl gasket sits or the raised outside edge (next to the float bowl gasket) of the carb body? Thanks!

parksie · Post by **parksie** » Tue Jan 27, 2009 6:38 pm

You measure from the"clean base" NOT the raised edge

frappy · Post by **frappy** » Wed Jan 28, 2009 1:33 am

parksie wrote:You measure from the"clean base" NOT the raised edge

Thanks parksie. I added a picture so that readers are absolutely clear as to what question's being asked and answered. The adjustment is in fact 27.3 mm from the gasket surface as shown in the below picture. (Please note: camera parallax makes the measurement appear incorrectly @ 1.3mm less than proper 27.3mm for the T500-J,K,L,M.)

This was a critical question for me to get answered for two reasons; both carbs on my bike had float adjustment problems. One float was seriously mangled by a careless PO and badly out of adjustment, while the other was not bent, but set improperly from the raised edge.

frappy · Post by **frappy** » Thu Feb 05, 2009 1:15 am

Last night I made an interesting discovery - the new float I just purchased from Suzuki weighs less than the original Mikuni float!

I couldn't tell by touch, but discovered the difference in weight upon installation. (Might this have to do with the type of solder they used back in the 70's, or could it be the float alloy material?)

Anyway, I installed a new Suzuki needle valve set in each carb. I then inverted the carbs and installed a float in each carb to prepare for setting the float height. The original Mikuni float slightly compressed the needle valve internal spring, whereas the new Suzuki float did not compress it at all.

I verified it was the float that was heavier and not a weaker internal needle valve spring by swapping the floats between the two carbs. Again, the old float compressed the needle valve spring similarly in the other carb. (Please note I did soak the old float overnight in gas to confirm it wasn't leaking - and it neither sagged nor sank.)

I was planning to use the original "heavier" float, but figured I'd better not and today ordered another new Suzuki float for my other carb. Is this smart or am I just wasting money on the new "lighter" float?

Dane

bikegeezer · Post by **bikegeezer** » Fri Feb 13, 2009 8:12 am

I don't think you're wasting money. If the floats are set the same but don't weight the same (or very close), then your fuel levels will be different.

Stu

tz375 · Post by **tz375** » Fri Feb 13, 2009 9:32 am

Frappy, just to be sure here. When you mentioned that the original heavy float compressed the light spring in the needle and float assembly, you didn't mean that happened when you were setting the float height did you?

That is one of teh things that makes float height setting difficult. the carb has to be at an angle so that the float is just touching the needle and the spring is NOT compressed.

Post by **Suzsmokeyallan** » Fri Feb 13, 2009 9:33 am

I'll bet the old float has a lead based solder mix in it and thats where the little bit of extra weight comes in to play. Today that would be a big 'no no' for sure.
Youre right to get two floats the same weight, its the correct thing to do.

frappy · Post by **frappy** » Sat Feb 14, 2009 3:34 am

tz375 wrote:Frappy, just to be sure here. When you mentioned that the original heavy float compressed the light spring in the needle and float assembly, you didn't mean that happened when you were setting the float height did you?

That is one of teh things that makes float height setting difficult. the carb has to be at an angle so that the float is just touching the needle and the spring is NOT compressed.

tz375: That is exactly what happened: I set the float height with each carb completely inverted (i.e, perpindicular to my workbench). Like you, I was initially surprised to find that I could set the float height in both carbs by placing them upside down on my workbench. However, with the new needle valve and new float I was able to set float height without angling either carb whatsoever.

I appreciate that you mention being sensitive to compressing the little spring in the needle valve springs. That is paramount when setting float height - to not compress the little spring whatsoever. In fact, I recall that setting the float on my CB350F carbs did require each carb to be angled, even though I had installed new needle valves - it's just the nature of those carbs.

However, I will tell you that the old needle valves in my T500 carbs did, from years of usage, have weakened springs and they required the carb body to be angled to set the float height. I know this becuase I was initially planning to use my old needle valves since the seats were fine, but the darn pins were wobbly and springs weak.

Thanks for your input folks. I've got the new floats installed and buttoned up the carbs. I put the carbs back on the bike and levelled them to each other, I attached the cables, installed and adjusted the choke linkage. Once everything else (e.g., gas tank, air box, battery, seat) is back in place, I'll fire it up and synch the carbs with a manometer using the new vacuum port (thanks bikegeezer) on my second carb.

Dane