Setting HSC32 float heights dry.

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

 

Don't worry about it. Its their position when bowl is full you are concerned with. I can see how they would hang differently as there is nothing to make they exactly the same.

 

Good deal Bill, thank you. I sorta thought the same but it's always nice to have a second opinion.

 

You're fuel level is likely to be too low. 11/16 (17.5mm) is the setting.

 

Good catch I saw the 13/16th pop up a while ago not sure how it got introduced. 17.5 mm works great

 

Okay now I've confused myself. I think I meant 11/16ths but had 13/16ths in my head from reading earlier. I'll double check before I close them up. Thanks guys

 

HSC-series Hitachi carbs:
Height: 17.5mm (11/16th")
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): top of float
Fuel level measured via clear-tube method: 3 +/- 1mm


Also, I note for the few float heights that are specified for MIKUNI carbs, that the point-of-reference for the float height measurement differs between different versions of the Mikuni carbs.......on some, the measurement point at the float is the lower "plateau" area of the float, and for others it is at the very "top" of the float (and by "top", I mean the top of the float WHILE YOU ARE MEASURING IT----while the carb is actually upside down!----which, in reality, is the physical "bottom" of the float).

Okay, if you're read all of the above and are not fully confused, well, it means that you just haven't been paying enough attention..........

P.S. I do NOT have any float height measurement diagrams for Mikuni carbs, as I don't yet have all of the float height measurements by carb, nor the reference points. If someone can provide those, it would surely be appreciated. The table below summarizes all of the Mikuni info that I've been able to crib together, with missing info noted by the ??


550 Mikuni carbs:
Height: 21.5 +/- 0.5mm
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): ??
Fuel level measured via clear-tube method: 2 +/- 1mm


650 Turbo Mikuni carbs:
Height: 17.5mm +/- 0.5mm
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): ??
Fuel level measured via clear-tube method: 2 +/- 1mm


XJ700-X/750-X Mikuni carbs:
Height: 17.5 +/- 1mm
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): upper "plateau" of float
Fuel level measured via clear-tube method: 3 +/- 1mm


900RK Mikuni carbs:
Height: 22.3 +/- 0.5mm
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): lower "plateau" of float
Fuel level measured via clear-tube method: 5 +/- 1mm


1100 Mikuni carbs:
Height: ??
Measurement reference point 1: carb gasket base, without the gasket in place.
Measurement reference point 2 (at float): ??
Fuel level measured via clear-tube method: 3 +/- 1mm

 

If you check the Yamaha service data (1981 and before) it has the float height for HSC32 carbs specified at 17.5mm (+/- 1/2 mm). Somewhere I got the idea that that measurement should be take perpendicular to the gasket face (gasket removed) to the highest point on the float. I've always done them this way and came out at the low end liquid level (3-4 mm).

Since you're using 3mm more, and measuring to the parting line on the float body it seems to me your fuel levels would be way low.

The Mikunis on the 550 state 21.5mm (+/- 1/2mm). I only did one 550, and it came out right at 2mm fluid level.

 

May be a newbie question but, how much difference does the 2/16ths difference make whether they are set at 11/16ths or 13/16ths? I mean I know it must matter somewhat but what effect will it have?

Just curious

 

Where are you finding this info? I've looked in (original edition) service manuals and at the TSB's for the Hitachi-equipped models and cannot find it, help!!!

 

The Fuel Jets (Hitachi) or the orifices for the Jets (Mikuni) need to remain immersed in Fuel at all times ... including when the Engine is run at Full Throttle.
Should the Float Heights be incorrect; there is a possibility that the demand for Fuel could exceed that which an incorrectly Height Adjusted Float would allow into the Fuel Bowl, causing the Fuel Level to fall below the Jets or their orifices during peak demand, resulting in a Lean condition, or worse, Fuel Starvation.

Likewise, if the Float Height allows for too much Fuel to enter the Fuel Bowls; the Fuel will seek the level of its supply source and either spill out the Carb Overflows or seep above the Gasket Surface and flow out the top of the Emulsion Tube and into the Intake Manifolds where it will continue to flow into the Cylinder Head and through any open Intake Valves, down into the Cylinders and slowly begin to collect in the Crankcase.

Draining a Sump filled with Gasoline is costly.
Having the Bike run in a Lean Condition can cost you an Engine.
Being within Specs for Float Height keeps the bike running good all day long and spares you the expense of having to drain Gas from the Sump and trying to figure-out what the hell to do with it after its drained-out!