. . . . . . . stupid shops....

On the pics for the 650 hitachi carbs.... on the third picture, those little jets, what i am thinking is the intake jets... are those all supposed to be the same size?

"One set is the main air jets, it should be smaller than the pilot."

THE JETS ARE UNDER THE DIAPHRAM?!?!?!

I want to really hurt that stupid mechanic.... They should pay me back for those parts Chacal was nice enough to locate for me....
How inept can one person be????

THEY WORK ON BIKES FOR A LIVING!!!

 

Jack, they work on literally dozens if not hundreds of different bikes. They know a lot about the generalities of all of them and very little about the specifics. It is wise in this case to seek out a specialist for assistance on anything beyond which way does the bike point and where does the rider sit. Again, I offer my assistance if you should hit a hard spot. I'm about 2 hours or so north, perfect ride opportunity (better hurry, October is booked 3 weekends in a row).

 

Not that I think this pot needs stirring any more than it has been, already.

Mikuni and Hitachi are to motorcycles as Holley and Edelbrock are to cars.

I can't imagine 25 Years going by without a motorcycle mechanic not being introduced to a set of Mik's or Hi-tot's at one time or another.

I would have to give the mechanic a vote of "No Confidence" for how this chapter is playing-out.

There's them that can.
Them that do.
Them that say they can.
Them that say they do.
Them that can't ... even if they say, "They can and do."

I think your Cowboy Mechanic is all hat and no cattle!
That there is my take on the matter before us.

I've been wrong before.
Once.
When I said I sure that I was wrong; and I wasn't!

 

Jack----which picture(s) are you referring to? Link?

The main and pilot AIR JETS are underneath the rubber vacuum diaphram that is attached to the big brass slide piston. To get to the AIR jets, you remove the chrome carb top "hat" (technically called---get this---a "diaphram cover"). Now you'll see the big black rubber vacuum diaphram. Remember, this rubber diaphram is attached to the brass piston (in the "center" of the rubber diaphram). So the rubber diaphram and the brass slide piston will CAREFULLY come out as one unit (note: you may have to CAREFULLY peel the edges of the black rubber diaphram away from the machined groove in the top of the carb body....CAREFULLY is the key word!).

When you lift the diaphram/piston assembly out, the long skinny aluminum main jet Needle will come out with it, as the needle is attached to the piston via a hex-drive plastic nut (located down in the center of the piston). If all you're doing is replacing the air jets, you don't need to diassemble the needle from the piston.

Off to the side of the piston bore in the carb body you will either see the AIR jets, or you might see a cad-plated air jet cover plate held down by a flat-blade slot screw. Remove the screw and gently remove the cover plate and viola, main and pilot air jets in all their naked glory.....

(NOTE: CAREFUL: when re-installing the diaphram/piston/needle assembly back into the carb, you'll find that the needle is actually "tilted" off center---by design----and usually won't drop into the small opening in the emulsion tube (a/k/a "power valve") below.

You should GENTLY lower the diaphram/piston/needle down, and then by rotating the entire assembly you can get the needle tip to eventually line up with opening in the emulsion tube. You can also stick your pinky into the carb venturi and gently guide/push the needle into position so the tip enters the warm, loving caress of the deep, seductive, inner depths of the emulsion tube........ Whoops, sorry, got carried away. BUT WHATEVER YOU DO, don't let the needle tip get damaged or "flattened" when trying to get intercourse, oops sorry, Penetration, whoa!, I mean "entrance" into the emulsion tube port.

BUT, once you do get the tip into the bore--even just a tiny bit---then LET GO OF THE DIAPHRAM and see if it falls easily and without friction or resistance until it "hits bottom".....this is the infamous RickOMatic "clunk test"....and if not, a very fine polishing of both the brass piston AND the carb body bore with 800-1200 wet polishing paper is required.

Also...if you don't need those #80 main air jets, please feel free to return them....100% refund except for shipping.....I'm feeling your pain and want to fly out to California and kick those guy's asses myself......


P.S. the main and pilot FUEL jets are located down in the bottom of the carb body, where the float lives. Their sizes should be #120 main fuel and #40 pilot fuel.........fuel jets are easily distinguished from air jets, as the fuel jets have a "head" on them (kinda like a screw) that is larger in diameter than their threaded shaft. AIR jets have no head at all; the head and the threaded shaft are the same diameter.

 

P.S. yes, the main AIR jets are SMALLER in size (the jet opening part) than the pilot AIR jets (although both the main and pilot AIR jets are the same overall physical size, shape, threads, etc. It's just the drilled center hole that is different in size between the two).

This is opposite from what you'll find on the FUEL jets...the main FUEL jet is larger in jet size than the pilot FUEL jet....although, again, the main and pilot FUEL jets are overall the same size, shape, head size, thread size, etc., etc. It's only the drilled central hole that differs between them.

 

Rut-roe.....if you are talking about the third picture down on this thread:

http://www.xjbikes.com/Forums/viewtopic ... art=0.html

what you are looking at is the "air compensator jets"---off to either side of the butterfly valve----and they have HUGE openings, even though they are stamped "36" on them. Not only do those jets never, EVER wear out, most people don't ever remove them when rebuilding their carbs (except for me, of course!) because the air passage behind them is HUGE and can easily be blasted clean with a spray can of carb clean, etc......heck, you could probably fit a small firehose down those ports!

 

Jeez chacal, I didn't know that carb work could be so exciting! 8O

I guess now we know why you are so intimately familiar with the hidden recesses of these little beauties - the rest of us seem to have been missing out on a good deal of the... umm... satisfaction you seem to experience during this process.

 

Well, like I've always said, it takes a REAL MAN to properly "service" an HSC32 carb rack.........

 

The work necessary to do a complete and thorough job of cleaning a 4-pack of Mikuni's or Hitachi's isn't difficult. It's complicated for the inexperienced. It's routine for those who have done many.

The Pitfalls are many. Age alone, makes some of the components hard to remove or disassemble. But, since the Carbs are primarily Aluminum and Brass ... they do clean-up, factory fresh after treatment with the proper Cleaning Agent.

The most difficult part is getting stuck parts loosened. With a few "Handy-Dandy" special tools ... you can overcome that obstacle too.

Screwdrivers that are 100% an EXACT fit to the Slots on Screws and Jets cannot be overemphasized.
Heat sources: Propane torch with Pencil Tip flame. Butane lighters: B-B-Q Style and Head-shop Specials for heating-up small areas.
Vegetable Oil to lube the stuck parts and not burn-off or flame-up too easily.
A Drill bit with a shank that FITS the Inside Diameter of Mikuni Float Body's to allow them too be grabbed and extracted with ...
Needle Nosed Vice Grips.
And, one of the MOST Important tools you should have for removing Stuck fasteners ...
A Hand Held 1/2" Drive Impact Tool.

Then, there's Q-Tips, Pipe Cleaners, Rifle Barrel Brass Brush, tooth brushes, and Dental Office Cleaning tools, and a set of Welders Tip Cleaning Tools.