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.

 

Kordasn,

The answer to your question is yes, just like photo 2 you referenced.

 

On the Mikuni BS28 (XJ550 models) dry float height is 21.5mm.

 

After doing that job the last time I now own digital calipers too. Harbor Freight has them on sale

I think it will be easier than my trusty scale. Which by the way I found is also available at Harbor Freight - gotta love that place.

 

Is that so? The service manual I found for my XJ700X said the dry float height was 17.5mm +/- 1mm like the Hitachis, but there is no physical way that was possible. Where did you find that info at? I'm not doubting you at all. I adjusted the float levels on my Mikuni's using a clear tube and I took a rough measurement of the float height so I could set the rest and it was at 22.5mm, so your spec sounds pretty good

 

Where did you gleam this little bit of truth and righteousness from............????

 

This is as Old School as it gets.
Works, though.

Cut the cotton tip off one end of a Q-Tip.
Measure 17.5 mm's up from the end you cut off.
Mark a thin line on the Q-Tip handle you can see.
Now you have an accurate Tool for measuring Float Height.

Set the cut-off end on the Gasket shelf without the Gasket.
Make your adjustment so the Float is right on the line.
Bingo!
All four should be right on-the-money!

 

You want me to tell ALL my secrets?

81 and earlier Yamaha listed the float heights in the service data section of the parts fiche. Go back into the 70s machines and they have torque specs there too.

Apparently after 83 they dropped all service data from the fiches.

 

Oh God no!

Just this one will be enough.........

 

All the data is presented in the addendum section of the Factory Manuals.

 

so what would the height be on a 83 750?

 

about 13/16" from the base of carb body (where the bowl gasket sits, but NOT including the bowl gasket!) up to the "mold line" on the floats, at the outer end of the floats (as far away from the float hinge as possible).

 

so this is with the carb upside down (compared to being mounted on bike)? and than adjusments are made on the "tang"? correct? and that is that little tab that bumbs up against the float pillars and not where the floats hangs. right?

 

Mostly upside down. The needle has a spring so you want to tip the carb enough so the weight of the float does not depress it. About 45 degrees - you want it to touch but not depress the post.

The tang is what you adjust it is the part that contacts the needle. Small changes are advised - it does not take much bending usually.

Also measure both "pods" of the float, it is not hard to get them off level when bending the tang. If your careful you won't have a problem.

 

Here is how I measure my floats dry. Obviously, I do it with much more precision and I was being pretty non-chalant and posing for the camera



So I zero out my calipers and then open them up to about 30mm or so. I place little bar that protrudes out the back on the gasket mating surface of the carb body. I then slowly bring the calipers down until they just touch the top of the float buoy. I normally just look for the slightest movement in the float to tell when I have touched it. Sometimes I'll need to back off to 30mm again and redo the process because I pushed down too far. Adjust the metal tang on the float and redo the measurement.

The float in the picture is one that I believe was never messed with or opened up and it measured to be 21.45mm (the picture shows different, but I was just taking a quick shot for the camera). So I believe that the 21.5mm measurement as indicated earlier in this thread may be on point. I just recently reset the carbs from my XJ700X to that spec and will do a wet float height to confirm when I get them back together.

 

Punch the Fluid Height Window out of that Brake Master Cylinder and get a Wristwatch Crystal in there.

Nice "Show and Tell" with a fine visual.
Them-there calipers sure beats my using a marked Q-Tip Stick by a mile or two.

 

So 13/16 is the "magic" number? Being really bad at fraction been a long time since 4th grade (really long). I bought a ruler like Bill's picture but it measures in 32's and 64's what would be my measurement be on this ruler.

Chacal, I found mine at Harbor Frieght for 1.99.

THanks for all the help.

 

13/16th's = 26/32nd's = 52/64th's

 

wow just took off the carbs again! and am trying to get a handle on measuring the float. SO once again this carb rookie is lost. I get where I am measuring from the back (ie farthest part of the float from the needle) but am I holding the float up or should it be free? When I apply pressure to the float (like gas was moving it) than my measurement is close. But with it just sitting there it is way off.

Sorry guys I am just not getting it.

 

Carbs upside-down, floats should be hanging under their own weight. The 13/16" measurement is where you want the float to rise up to and STOP (when the carbs are right-side-up and full of fuel) and thus CLOSE the float needle into the needle valve seat.

When the carbs are upside down, the floats are pushing on the needle and closing them against the seat, which mimics what the fuel level will do to the floats.

 

13/16th's?
Why are we Owners of Metric Motorcycles and stating measurement values in fractions of an inch?
Fractional measurement died some time ago.
We should be stating all measurement values pertaining to our bikes using the Metric System.

That Value should be stated in Millimeters.
The fractional value of 13/16th's of an Inch = 20.63 mm

 

I would say it's most likely due to the fact that most owners don't have access to a micrometer or metric ruler. The fractional value of 13/16" is present on 99% of tape measures, which the common backyard mechanic has in his/her toolchest (I say 99% for the ONE tape measure that doesn't!).

Now, for whack jobs like me who need the precision and own three sets of digital calipers, I prefer the measurement in millimeters. As per a previous post in this thread, the Mikuni carbs have a dry float measurement of 21.5mm +/- 1mm. I believe the Hitachi carbs are 17.5mm +/- 0.5mm for their respective dry float measurement, however, "sources" at Hitachi say that the dry float measurement is 13/16". Fun with numbers, I say!

Please, though, someone correct me if I am wrong!

Edit: I confused myself and had to reread the thread. All should be well now.

 

Ok getting there,

So the float under it own weight (upside down) should measure the 13/16. so from the lip of the carb (without gasket) to the upper part of the float (really the bottom, if carb is right side up) should measure 13/16.

If it does not (mine don't) where do I make adjustment, to get it to the proper height? if I move what I think is the "tang" that does not change the height of the float. Should I make the adjusment where the needle loops onto the float?

 

From the flat base of the carb body WHERE THE GASKET WOULD SIT (but without the gasket there) up to the "mold line" on the float is the 13/16" measurement (=20.63mm).

Yes, make the adjustment to the needle "tang".

 

RickCoMatic previous comment>>> "Punch the Fluid Height Window out of that Brake Master Cylinder and get a Wristwatch Crystal in there."
Hey mine looks just like that and possibly worse! Anyone have some info where to get a new "looking glass window"?

Thanks
'82 XJ650J

 

Hey, glad you asked!:

Master Cylinder Sight Glass:


mc2) While you're rebuilding or even replacing your front master cylinder, you might as well go ahead and replace that dull, clouded, cracked thick plastic sight "window" that allows you to see the level of brake fluid in the reservoir. The original "transparent" round plastic window ages neither gracefully nor well over time, and becomes cloudy within a few years. Our replacement flat mineral glass windows are the correct size, they won't ever get cloudy, and are one of those small details that you can step back, look at, and say to yourself: "Kewl".

Okay, all that's the good news. The bad news is that the old plastic seal can be a beast to remove. Sometimes, they come out all nice and easy. Sometimes, you have to struggle, and do as that classic old Pink Floyd song suggests: "One of these days, I'm going to cut you into little pieces......". You get the idea. You'll have to fight, struggle, and then win. Clean out the edges of the bore exceedingly well, and make sure that all remaining pieces and remnants of the old window and adhesive are gone before gluing in the new window.

And while you've got that old sight window out, go ahead and dig out the thin aluminum disc that lives right behind the sight window, and which restricts the view of the fluid in the reservoir. Although this disc never wears out, it does hinder you from getting a good view of the fluid level. Again, just carefully pry it out.

Finally, you'll need a good quality adhesive to install the new sight glass into the cylinder body. Although there are probably lots of brands of gasket-maker/sealant material that will work, we've found one that is black, easy to work with, and is impervious to brake fluid (NOTE: if you're going to try to use some gasket material that you have sitting around, make DARN SURE that you test it to see whether brake fluid attacks it or prevents it from hardening (almost none of the major gasket-maker materials have been "tested" by their manufacturers against brake fluid, since you do not normally ever use gasket-sealant material in a brake system).


HCP1074 Aftermarket front brake master cylinder glass brake fluid level SIGHT WINDOW, correct size and thickness crystal-clear mineral glass. NOTE: Fits all models that have a pressed- and glued-in original sight window. Does NOT fit original master cylinders that have an o-ring and c-clip retained ight window. Each:
$ 5.95

HCP9819 Aftermarket front brake master cylinder glass brake fluid level SIGHT WINDOW, correct size and thickness crystal-clear mineral glass. NOTE: Fits all models that use an o-ringed and c-clip retained original sight window. Does NOT fit original master cylinders that have a pressed- and glued-in sealed sight window. Each:
$ 5.95


HCP3120 Aftermarket black GASKET MAKER, 3.8 ounce squeeze tube. Enough to do about ten thousand sight glasses! But it's the smallest size offered. I'm sure it works well in other applications. Each:
$ 5.50

 

"The Old School Method"
Replacing Site Glasses with Watch Crystals
by: Rick Massey
All rights reserved.

I mixed some regular 5-Minute Epoxy. I used the narrow ends of toothpicks (many) to place the small amount of epoxy behind the crystal. [It was more like a "smear" than it was a bead.]

The outside sealing got done by placing a partial drop of epoxy at the edge. Tossing the toothpick that was used to apply the epoxy and using many other toothpicks (I had a half-dozen between my lips) to "drag along" the freshly mixed sealant taking advantage of its slow capillary action.

I used a bunch of soda cans and shot small amounts of UN-mixed epoxy on the concave bottom of the can. Then, when the epoxy you are working with just begins to "Pull" ... shitcan that mix and blend yourself one of the UN-mixed ones you have lined-up.

Once you have the sealing bead all around the new CRYSTAL ... take full advantage of it being crystal and shape the epoxy around the inside diameter of the window.

Use your little finger moistened with "Good Old-Fashioned Spit" (saliva) to make a nice looking finish ... like a glazer would do on a window.

Clean-up BOTH the Crystal AND the shape of the seal with lacquer thinner.
Use old, cotton, T-shirt cloth and moisten the cloth stretched tightly about your finger. Closer to "Damp" than "Moist"

The lacquer thinner will clean the glass off anywhere you might have goofed while simultaneously helping you apply a really fine-looking bevel on the epoxy around the glass.

If it isn't crystal or glass and you touch it with lacquer thinner; you'll be back to Square One, immediately.
- 30 -

 

Dang chacal do you have every frekkin' part that I need or what?!!! (I'm thrilled you do!) I may need to get your bank routing and account number to have my paychecks direct deposited to you if you keep this up. *lol*

I love this place!

 

I would not use a tape measure.
A steel rule, yes, and mine have have metric and SAE down to 100ths.
My dial calipers also do not measure fractions, but decimals in inches
My digital caliper measures in metric and decimal inches. Still no fractions.

Funny note to go along with fractions and decimals: My girlfriends 13yo 7th grader has to have a scientific calculator for school, and they use it to convert fractions to decimals and decimals to fractions. They dont know how to do it by hand anymore.
[We never used a calculator in school. When I got to tech school, we had calculators, but we had to show all of our work on paper, so doing it by had was just as simple]
(these kids today --The book report is done by information learned form listening to a 4 hour mp3 audio - no actual reading required)

 

Just wait until he/she gets to highschool and college where he/she'll come across some old school teachers/professors. He/she will learn how to do it by hand real quick!

 

Believe it or not, it's time to revisit this thread. Alright y'all here's my deal. I calibrated them according to these instructions and all 4 are adjusted to 13/16ths. When I flipped the rack over (right side up now) floats 1 & 2 "hang" pretty well even as a pair, and floats 3 & 4 also as a pair, but not 1 thru 4 as a set. Should they all hang (right side up) exactly even across?
Or does it matter how they "hang"?

Thanks