Carb breakdown

As discussed in a previous threadjack, I did a partial breakdown of a spare set of carbs that I had, and took lots of pictures in the process. Where can this wonder of the ages be found?

Right here!


The rest of it will come when I get parts and break the working set of carbs down, replace the seals, and reassemble.

 

nice job
careful pulling the pins that hold the floats
mark the floats too
put the bowls back on to protect the ears that hold the floats

 

Good call Polock.

Polocks cautionary remark concerning protecting the Float Hinge Pillars is not to be ignored. It's the smartest thing to do when the Carbs are going to be handled.

The Fuel Bowl can take a little bump.
The Float Pillar can't withstand much of an impact at all.
Keep them covered as insurance your hard work doesn't come to a screeching halt by fracturing a Float Pillar and ruining the Carb Body!

 

The guts I usually keep separated in little (marked) plastic baggies, so that's not an issue. As far as being careful pulling the pins, they slide out with no difficulty whatsoever.

 

yes the float pillars are definately shouldn't be ignored I went threw my carbs after 3 years of sitting outside and the pins and floats were rusted together and I did break one of the pillars. Not fun at all

 

Well, my carbs are Hitachis; I'm told that the float pins are much more difficult to remove on the Mikunis.

/The More You Know
//Still waiting on parts
///Probably should have paid for Priority Mail
////Slashies!

 

Speaking of removing the float pins for the Miks, I'm at a standstill on how to remove mine. Anyone care to share some pointers/methodology on the do's and dont's on extracting them?

 

determine if their stuck with varnish or physically stuck
carb cleaner for varnish, let it set for awhile, try not to get it down in the float valve, it may have a rubber tip
look at the ends of the pins for marks that someone else made knocking then out
if you see any marks, that end comes out
use a small drill bit and tap on the point to drive the pin out, till you can grab it with needle nose pliers, then twist and pull
i've unbent the float off the pin then twisted it out, then tried to save the float
don't bust the float pillars

 

Clean the dog snot out of the pins using carb dip, brake cleaner, etc. Tap lightly on them, both directions.

Put an ice cube on the float/pin....you want to super-cool the pin itself as much as possible. This may take a couple of minutes of holding an ice cude on the pin area. Don't get the ice cube on the pin post.

Try knocking it out again. Probably won't help.

Get a propane torch (or similar) and CAREFULLY heat up the pin post, both above and below the pin. CAREFULLY! You don't want to melt it, whcih can happen. Aluminum doesn't start turning red as it approaches heat saturation; it just melts, so you don't have that "warning sign" to cue you in.

Try tapping it out again. If it still doesn't work, re-apply ice and try the heat thing again.

Be careful.......

 

Get one of those Butane Lighters like you can find at Comic Book Stores or Head Shops. Heat the Hinge Pillar around the Hinge Pin.

Drive the Hinge Pin out after heating the Hinge Pillars.
But FIRST ...

Place the Hinge Pillar against the edge of your work bench or a support structure that will absorb the impact and NOT let the end of the Hinge Pillar move with the impact.

Once the Hinge Pin has moved-out slightly ... Grab the end between the "Head" and Hinge Pillar with a GOOD pair of Diagonals.
As you are Holding the Hinge Pin Shaft -- tightly -- with the Diagonals ... apply a rotational force and Impact TO THE DIAGONALS.

Apply Soldering Flux to each side to the Hinge Pillars where the Hinge Pinn passes through. Heat the Hinge Pillar and get the Flux to lube the drilled-through ends of the Pillars.

 

Thanks for all the advice. I did manage to get them out with a few carefully placed strikes on the end of the hinge pin with the flattened end of a nail and a ball peen hammer. After overcoming the initial resistance, they slid out fairly easily using needle nose pliers.

One more question... what should I look for in determining if the float needle and or valve needs replacement? Aside from some varnish build up on the float valve, I can't tell if they need to be replaced or just cleaned. The float needle tips look to be in great shape. Comments?

 

Regarding the float valve NEEDLE: always replace them....it's cheap insurance.


Aftermarket Mikuni float valve Needle Only...for those who wish to do an extreme-budget rebuild, you can buy the rubber-tipped float valve needle by itself (without its brass seat).

For use on all XJ550 models, all XJ700-X models, and all XJ1100 models:

HCP1670 Mikuni float valve Needle with retainer clip, each:
$ 8.50

HCP1670SET4 Mikuni float valve Needle with retainer clip, set of 4:
$ 29.00


Regarding the float needle SEAT: look for any wear/build-up in the area where the needle rubber tip contacts the valve. Remove any build up CAREFULLY.....like with an acetone-soaked q-tip. You don't want to remove any material----this is a precision-fit area, where the tip seals against the seat, and even the smallest "oversize" condition of the seat will likely result into a leak, with all the attendant problems of such. If needed, replacements are available:


kk) Aftermarket Mikuni Float Needle Valve Assembly---contains the float needle with retainer clip, float valve brass seat, the seat o-ring, and the seat filter screen.

For all XJ550 and XJ1100 models:

HCP1672 single float needle valve assembly, each:
$ 31.00

HCP1672SET4 float needle valve assemblies, set of 4:
$ 119.00

or:

Aftermarket Mikuni Carb Lower End Rebuild Kit---contains the float needle with retainer clip, float valve brass seat, the seat o-ring, the idle mixture screw block-off cap, and a bowl gasket.

For all XJ550 models:

HCP1669 aftermarket Mikuni Carb Lower End Rebuild Kit, each:
$ 21.00

HCP1669SET4 aftermarket Mikuni Carb Lower End Rebuild Kit, set of 4:
$ 72.00

 

Updated file is available.

Hitachi Carb Breakdown

 

Schmuck....that's a beautiful thing.

Thanks again for all your efforts and posting it!

 

I'm still working on those edits you suggested. I added the preface page tonight, and over the next couple of days as time permits I'll be adding arrows to some of the pictures. (Just in case people can't figure out what spacers look like.) After that, it should be pretty much done.

 

Okay. The whole thing is more or less finished. Here you go:

Hitachi Carb Breakdown

Enjoy!

 

Impressive.........!

 

Great tech article.
I'm planning to resurrect my XJ650RJ and am now collecting parts and tech advice.
Any source for replacement screws for the carb hats?
Recommended rebuild kits? I see sets sold through eBay.

Thanks
Nick

 

Good to see you corrected/switched the #1 & #4 bowls! This should be "stickied" in the XJ FAQ Final forum. Great documentation!

 

Nick, you will find Chacal carries all the parts you are looking for. Look up his thread in the "For Sale" forum.

 

Well, I broke a pin post off.
Mikunis.
#1 came out with no issue.
#2 didnt budge and before I knew it, I'd broke off the pillar.
#3 & #4 both didnt budge but I was being more carefull and using less pressure.
When I got the #2 pin free, it was bent.

My little butane crack pipe torch wont stay lit. My MAPP gas torch is very big and hot for use in such tight quarters.
Besides attempting to use heat, ice cubes aint gonna cut it, so I chilled the pins with an upside-down can of compressed air. Instant frostbite when applied to skin. (Dont do it) Fairly concentrated too. Ill get a new micro torch, and hopefully combine the cold and heat the next time I have a sticky situation like this.

I looked at #3 and #4 again and decided Id use my tiniest Dremel bur and make sure there was no mushrooming.
Of course the vibration of the bur against the pin probably helped.
I still wasn't getting the pin to move, and just no good way to tap it.

Enter spring loaded center punch. #4 easy-peasy. #3 a little harder to get at - not straight on. I ground a little dimple in the end of the pin. And out she pops.

Besides replacing the bent pin, I will either swap out the broken body or attempt the JB Weld fix.

I did look at unwrapping the float from the pins, but there is a sleeve inside the float hinge that may still have made it difficult to wiggle the pins out.

I haven't got any emulsion tubes out, but all pilot screws and primary and secondary jets came out fine. The mixture screws were plugged, and the screws look like they had a single screw driver slip each.
Enrichment valves next.


weeeeeeeeeeeeeeeee

 

That's about as complete as one can get. BROVO for your efforts! Good photos too. It's people like you that make this forum well worth logging onto.

 

Steve, I should have some good used carb bodies (BS28 Mikuni) available if you need a replacement............

 

Don't JB Weld it. An experienced watch maker couldn't get the geometry straight. You'll be binding the Float Pin or having the Fragment fall-off.

Look around for Parts Carbs.
I have a vew Hitachi Bodies I can see but I don't see any Mikuni's ... but, there's some non-labeled boxes I can look in.

The part you need it out there ... find it!
Call at least ONE Bone Yard and get on their Network.
Life ain't all eBay.
You actually might have to buy it from a Motorcycle Salvage Co.

 

I do have spares. Funny thing while I was taking the bowls off the bikes original rebuilt carbs - all pins came out with very little effort. I have 4 spare straight pins.
#2 had the pillar broke off @ the hole but the pin was mostly captured.
#4 I actually had a hard time getting the float out, as it was bound by the pillars. They actually look slightly twisted, but never broken and repaired. That float fits between the other pairs of pillars with no trouble. None of the other floats will fit in that position either. How did they check the float level and all that if the float doesn't move?
I dont know who rebuilt that set, but they suck!

I will be putting in an order to chacal as I'll need bowl gaskets, head to carb boots - All 8 screws came out with no trouble, but the rubber cracking just looks too deep to bother with attempting repair/patching. I'm still building a list.

Steve

 

Okay, just let me know, thanks!

 

Hrmph. In order to try and keep the posts from flexing, what I did was stop by the local Home Despot, and grabbed a 31 cent piece of metal they referred to as a "nail stop". I cut out a section just wide enough to wedge between the posts, and went at it.

I'm putting together an illustrated writeup for the Mikunis, using the cleaning article on the XJCD as a base; this will NOT involve breaking the rack.

More as it becomes available.

 

Our mechanics out here with CAT use dry ice to cool parts for easy removal. Maybe something to consider. Probably not great with smaller parts as they might snap easily.

 

The pdf is great. Thanks for your time doing that!

 

If I find a stubborn Float Hinge Pin that does not want to come out ... I treat it like somebody was there before me and couldn't get it out ... either.

On Mikuni:
I use a Dremel Yool with a Extra-fine Sanding Bit and burnish the side of the Hinge Pin that DOES NOT have the "Nail Head".
I figure somebody tried to drive it out and "Peened-over" the end making the extraction very dangerous and difficult.

Then, using a Special Tool I grab the Pin on the Nail-head end and let the tool work it out.

The "Special Tool" is a pair of wire-cutting diagonals that I have purposefully "Dulled" the cutting-edges.
Place the "Dykes" in your vice and "Shoeshine" the cutting-edges dull with
400 Grit Sandpaper.
Take the sharp, cutting edges off both sides of its "Jaws"

The Tool becomes a "Grabbing Wedge" for getting between the Pillar and the Nail Head.
Grab the Hinge Pin tightly.
Then, with the "Pendulum Swing" of a large screwdriver ... Impact the Tool close to its Jaws and draw-out the stubborn Hinge Pin.

Needless to say ... you need to be very careful dealing with a stuck Hinge Pin because one false move will ruin the Carb if you make contact with the Hinge Pillar and fractaure it or break it off.

As "Schmuckaholic" did. Improvise.
Find something that will reinforce the Hinge Pillar if you are going to use a small drift or a fabricated tool to drive-out the Hinge Pin.
Something to place the Hinge Pin up-against ... so it will not move as you impact the base of the Pin.

 

BEAUTIFUL, and I am inpressed! Great work, thanks!

 

nice job on the pdf but how do i know what kind of carbs they are? i have a 85 xj700 and i dont have the manual

 

MasterKrause,
Check out the name of the PDF file.

 

About the easiest way to quickly determine which rack of Carbs you have on the bike is to look at the Chromed Top on the Number-1 Carb.

If the Top has a small angled "Ramp" on it ...
They're Hitachi's

If the Top is completely round, without the ramp ...
Mikuni

 

All the links to the pictures or diagrams are gone. : (

 

Link has been updated again (12-3-11). The available list of files is here.

Actually, I'm redoing that file a bit -- shrank the pictures down a bit and moved the text around. End result: smaller file.

I really should rename that file -- it's not so much breaking the things down for cleaning as it is changing out the throttle shaft seals, so I'm not removing the emulsion tube, nor the fuel jets. Maybe one of these years I will do that and hack another file together... but there's a file on the (cover your eyes, Rick!) XJCD set that shows the procedure. However, it doesn't illustrate a walkthrough and the pictures are small/hard to read the captions.

(edited 12-3-11)

 

thanks dude

 

Does anyone know what happened to this link ...

http://mok.fileave.com/Hitachi%20Carb%20Breakdown.pdf

My browser is telling me page not found.

 

My Browser (Firefox 8.0.1) does not allow that site to load.

Firefox says the site is dangerous.

 

Rick ... any idea how we can get the pdf?

I've got some issues with my carbs flooding and I'm using the aftermarket float needle valves with the longer needles. I'm suspecting the geometry was ok when I first put them in but flooding a few times has probably messed up the settings.

I'm also going to polish them up a bit better because the bores on the float valves have circular marks from whatever the last process in the manufacture was.

 

Shoot a PM to "schmuchaholic" (sp?).

He's got Carb .pdf that's terrific.

 

I edited the post a few upwards to update the link. The forum post with the list of files (you get not one, but two different download sites to choose from!) is here.

Len and I are trying to get a dedicated web page up for this very purpose. Do we have any web geeks floating around here, perchance?

My earlier version of FF just spits out a 404. Going to www.fileave.com has a domain parking page from someplace in Phoenix AZ.

I had horrendous issues with one or more bowls overflowing/fuel levels not settling in the last time I went through the Mikunis on my X. Changed seats, needles... turned out that when the floats were hanging down, they were sitting so low that they pulled the needles off vertical, and they were binding.

I bent the other tang on the floats (not the one for the needle; the one that rests against the float pillar) so that the floats didn't sit down so low. The result was like magic.

 

Hey Schmuck, thanks ... I was just about to pm you for these ... Cheers, Ian