Setting HSC32 float heights dry.

This is a response to a question in the Carb clinics section asking how to set up the floats on an HSC32 carburetor "Dry"

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The XJ650 uses the HSC32 carb. In 1980 Yamaha listed a dry height of 17.5mm +/- 0.5mm. In 1981 they listed the previous number and the 2-4 wet number. In 1982 they dropped the dry number.

I've never had to reset an HSC32 that I set up to the dry number.

The measurement needs to be taken perpendicular to the lip - from the lip to the bottom of the mid point on the float buoy. The carb needs to be inverted, and you need to make sure that the spring in the float needle isn't being depressed by the weight of the float - so you might need to hold them at a 30deg angle.

 

Thanks for the input, the holding on an angle is a good strategy.

 

See, that's the information I've never seen in the previous discussions of the subject. Yes, the spec is 17.5 mm, but from where to where? I hadn't seen that answered before. Thanks, MiCarl.

So if I understand you correctly, you measure from the lip of the carb body to the bottom (and by bottom, I assume you mean "furthest from the float valve") of the black part of the float, is that right? (And here I was thinking you'd measure to the metal part.)

This is good, because I have one carb that I won't be able to set with the tube method, at least until I replace the bowl - the drain screw is in there for good.

 

Yes, somehow my feeble description was pulled from the fog!

BTW, those drain screws are easy to get out. Dry out the float bowl, screw it to a scrap of 2x4 and clamp in a vise. Heat the bowl with a propane torch midway between the screw head and the needle end. The little buggers practically jump out.

 

Yeah, that might have worked if I hadn't snapped off an easy-out down in there (while following the rest of that procedure). Nothing I have access to can even scratch that hardened steel bit (at least not without damaging the hole and the threads even worse).

Bowls aren't that expensive, so I'm going to replace it eventually, but I wanna be able to ride sooner than later...

 

MiCarl this is great wish I saw it Tuesday. I am trying to understand exactly where and how to measure. My before picture I am pointing to lower lip at "middle" of Float. Is this the correct place to measure at?

Also note how flat the floats sit. In the "after" picture they slope when adjusted to 17mm from that lower lip and in the middle of the float. I should note all my floats looked basically like this and I raised 2 of them 1mm or so as measured from the back.

I measured in the "back" when I did it Tuesday and still have gas getting in my oil. If the after picture is correct I can see where the way I had them set could cause the valve not to close or close loosely.

So do I have it right or am I way off? Thanks!

PS sorry for the blurry pictures but they get the point across....

 

Can anyone help me out here? I read another thread that says measure at highest point which would be at the back.

Thanks

 

yeah help me out too. i feel stupid because none of this made any sense to me. its like im reading the words but my brain isnt working. i feel like i have alzheimers right now.

bill, i dont see where youre "pointing" in your pics, maybe take them again focused?

 

yeah blurry - I was tired but now I can help you. Carl answered some PMs and I just went through it on my carbs tonight.

So to start - you measure off the gasket mating surface. The spec is 17.5mm.

If we call the hinge and needle seat "front" you measure at the "back" of the floats. The floats when adjusted properly will sit at an angle sloping up from the hinge. Ideally you measure at the midpoint ( in line with the needle valve measuring both floats at one - I just did each float to be sure they were set the same.

When measuring you need to tilt the carb until the floats are just touching the pin on the needle and be sure to keep your measurement at 90 degrees from the carb gasket surface.

I assume you know you adjust the height with the "tang".

It worked like a champ, only one of my drains works so I set that carb to 17.5mm then did the level - it was perfect. So I set the rest to 17.5mm then believe it or not I swapped the one bowl to each carb and checked the level. All were perfect. A pain but worth it.

See my thread on gas in the oil. I thought I set them right on Tuesday and flushed the oil only to still have the issue. I HOPE it will be fixed now.

I have now changed my oil 4 times in the month I had it (long story) and 2 more coming tomorrow to flush the gas out.

Anyway I know this is a strange order to do things but after I got the floats set I tore the carbs down for cleaning. I am confident now I check the height and be fine ( it should not change anyway if I don't bump anything). I'll try to get better pictures tomorrow on reassembly.

If you have any more questions feel free to PM me. I'm no expert but I now have experience tearing the carbs down a few times.

Let me add thanks again to Carl and a bunch of other - i read hundreds of posts on this subject and a bunch of the data got used tonight!

 

I think I'm close to full understanding here.

You say we need to measure at the "midpoint" at the back of the float. Is there a marking there? I see the seam that was made when the black part of the float was formed, are you refering to that? Or, should I measure the verticle thickness of the float, cut that number in half and mark it on the float?

Next, measure from the "gasket mating surface". There is a raised "rib" there that digs into the gasket when you put the bowl on. Do we measure on the rib or off the rib? I figure that rib is worth at least half a millimeter.

I know from the "clear tube on drain" test that my floats are too low. I'd rather try this than endlessy fill it with gas, measure, remove the bowls, tweak, install the bowls, rinse and repeat.

Thanks for answering all the mind numbing newb questions. I'm close on this one. I've NEVER had success on carbs. Even though I follow instructions to the letter, carbs and I don't get along. BUT! I feel I'm close to victory here!!

 

The mid point is actually between the floats. I ignored that advice since I was using a scale to set my floats. I just measured both floats to be sure they were even.

Measure to the "bottom" of the float. Remember of course you are looking at them upside down. I also ignored the ridge but a half mm is nothing as the spec is 3mm + or - 1mm.

Believe me I was very thick headed until I was able to set the float as I thought I understood then verify it with a fuel level test.

Here are a couple of pictures that may help..

 

Perfect! That nailed it for me. I finally understand. It should help save me some time. Thanks!

 

Cool glad I was able to help but the real credit goes to Micarl getting it through my thick head first!

 

Hello everybody,

It never ceases to amaze me how I can always find the information I
so desperately need at the moment. True to form here it was when I
needed it most.

Excellent thread for all of use new do it yourself people!

 

According to "sources" who have talked to the people at Hitachi, the actual measurement is 13/16" measured from the gasket platform (without the gasket, of course, and not on the raised rib) to the "mold line" on the float themselves.

P.S. Bill....where did you get that neat little float height ruler (or whatever it is)?

 

That's a Machinist's Pocket Ruler.
Very nice little tool to have in the inventory.

Mine's half as wide.
I measure the height of the Tang on the Float from the Base of the Carb in front of the Main Jet and Emulsion Tube Housing after having ascertained which of the four Float Heights was best to set all of them at.

Using a Scale that is accurate to 1/1000th ... I set the Tangs all to the same height using the one Height selected as "Correct" (or close enough for Govt work) ... to be the same all across the Board.

 

I got it in a cheap set that had it and some dividers etc years ago. When I got one float right I set the Tee and then used pliers to tighten it so it would not slip easily.

I wish it was half the width as Rick's is I'll have to find one of those. Mine is a bit wide for the job but works.

 

I have a question for all of those better versed in this than me. I took my carbs off recently, and I'm about to start putting some of it back together. So, do I have to do this measurement again?

If so, 17.5mm measured to what it shows in "carb2" above?

 

This is how I measured the dry float levels on my '82 Maxim 650, only I used a set of digital calipers

The first picture that Bill posted is exactly how I made my measurements. Thanks for posting those pictures up! Now, if only the Mikuni carbs were this easy!

 

I think this is exactly the forum ive been looking for! Didnt set the float hieghts when I had my carbs off pull them again and set hopefully ill stop having the gas coming out the pods.