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The illustrated carburator guide

Started by andyb, June 21, 2011, 11:02:33 AM

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This is a blurry picture.  Sorry about that.  It's also of the needle and associated parts again.

A - Needle.
B - Plastic retaining thing.
C - Clip.
D - Washer.  Sits atop the clip (to the bottom right as viewed here) and prevents the spring from getting into the clip, breaking, and going through the motor.
E - The spring.  This allows the needle to move around a bit rather than being absolutely rigidly mounted.
F - This is the plate that retains the needle, sundry washers/clips/crap and spring in the slide.
G - A lovely socketheaded stainless screw with locknut that holds 'F' to the slide assembly.  There are two, you can see the other sticking through the retaining plate.


This is the carb body as seen from below (bowl side).  The main jet, washer, emulsion tube, slide assembly, slide spring, and diaphram cover have all been removed.

A - This is the little nub that dictates what direction the emulsion tube faces.  If you're assembling things and it doesn't want to go, don't force it.  This is likely why it's not going in properly.  Line things up, maybe some lube, and try again.
B - That's a deep, dark hole.  It's also the location of the pilot jet.
C - This is the tang used to set fuel height/float level.  Remember?
D - This is the middle-ish part of the float.


Now for the post that I didn't want to make.

Even though it doesn't always feel like it, gasoline is flammable.  Smoking is frowned on when working with carbs that are full of fuel or even still smell like it.  Don't clean carbs around a campfire, got it?  Also, when you're using carb cleaner, for pete's sake wear safety glasses.  Yes, you look dorky.  You look really stupid when you're rolling around the driveway howling in pain, clutching your head.  Ask me how I know this.... When you're using carb cleaner and spraying it into a plugged passageway, it's like turning your kitchen faucet on full blast into a thimble (don't try that if the wife is home, incidentally, and have towels handy)... it WILL spray directly back at you and hit you in the face.  It burns like f'king fire if it hits you in the eyes.  I also wholeheartedly suggest that you have a fire extinguisher in your garage/work area (as well as a couple in the house, with smoke detectors, look both ways before crossing the street, etc).  However something that you may not have is a portable eyewash.  Get one, and store it next to the fire extinguisher or in the top of your toolbox, someplace very accessable.  They're inexpensive, and you don't want to have to run through the house to the medicine cabinet to get your eye washed out; again, I speak from experience.  If you do get carb juice or gas in your eye, wash it out immediately.  Go to a sink or use the eyewash bottle, and tilt your head in such a way that the bad eye is down (so you don't flush the crap into the other one).  Hold your eye open, and flush under running cool water for a solid fifteen minutes.  It will feel ridiculous after the first three minutes.  Do it anyway.  Carb cleaner will cause your eye to swell in a very nasty way and hurt like a bitch in the process.

Carb cleaner is capable of destroying a variety of things, including the surface of some tables.  Don't clean carbs on the kitchen table, your grandfather's priceless antique desk, etc.  

Use your head and you'll get to keep it.


I was going to go through and add part numbers, but not everything interchanges between the years.  Instead, I'm going to point you to this post.  Between the parts diagrams and these photos, you should be able to figure out what you need.  My personal advise is to go to RPM for your parts, though depending on where you're located you may have to look for alternate sources.  This kit is the current source for all of the kickass stainless hardware that my carbs are wearing, and it's unquestionably some of the best money you can spend on your bike, making working on the carbs a zillionty times easier.

I'm also going to point you to this post which describes the original equipment jetting as from the factory.  Then I'll point you to places like the carb section for more information on troubleshooting and modified jetting for various combinations.

Past that, you can always post questions in a new thread someplace, or use the lovely search feature.  Remember that when you have a modified bike and are looking to make changes, you need to take into account air density/elevation, and that different people have a different idea on what "running well" means!  The other thing I'm going to say is that if you think you're decidedly lean on any portion of the fueling, ensure that the carbs are CLEAN prior to changing jets.  A partially plugged jet is going to act like it's several sizes smaller than it really is, so you may end up cleaning and rejetting and becoming vastly rich--but it'll be better than it was and you'll not keep tuning because of your minor improvement with still so-so results.


Thanks Andy.  I'm thinking I might need to bite the bullet and pull and clean mine and not be so lazy.  I however couldn't help but laugh at the carb cleaner eye protection lesson.  It reminds me of a very embarassing lesson learned with a combo of weed, tabasco sauce, and scrambled eggs, one morning with my golf buddies prior to a tournement.  FYI, DON'T look INTO said bottle while rapping it on the table (note weed/stoner referance).  Man, I played some shitty golf that day.  :wacko1:
It's what you hold in your heart that's important, not what's in your hand, well, unless it the THROTTLE!!

Cash Dereszynski

Fuck it,let's ride.

Bud Wilkinson

Although I've done many hundreds of Mikuni carbs from single to multiple setups, it's always good to see what you are up against and what they look like before and as you go through them.
I can say from experience this is some great information. Very nicely done sir.
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85 FJ1100 - Sold - Sadley Deceased.
Honda Silverwing - Sold Real Fast
02 Harley V-Rod - Sold-COVID 19.
87 FJ1200 - Riding - YZF600R Wheel and suspension done.