Disassemble your carb, piece by piece, laying your parts out on a clean, open working area. If you lay them out in the order they cam off the carb, you'll have no issues with putting them back in, in the correct order.

Once done, you'll have a smaller carb body, that needs to be thoroughly cleaned, insode and out, making sure to pass air through all the air bleeds and ports. Remove everyting, including the main jet, pilot jet, emulsion tube (main jet scews into it) and the diaphram and associated parts.

Clean the body and bowl with carb cleaner and a tooth brush. I use a series of brass and mild steel brushes. Afterwards, I have a polishing process I developed, that's fast and efficient, making the carb look like new again.

 

One thing you may want to do, is to remove the air fuel mixture screw, and clean and inspect the tip. In the screw passage, there's a brass needle screw, a spring, an o-ring and a washer. Note the order they came out in. Note if there's any damage to the screw as it's thin and fragile. Clean screw and replace all removed parts in the order they were removed. Kits for rebuilding will come with a new o-ring. Replace it if removed.

Remove the "choke" cable. It is removed by turning the plastic 9/16" nut that threads into the carb body. The brass pintle on the end is what is moved within the passage when you pull the knob, with the thin needle end allowing more fuel to enter the carb, and the wider brass part allowing for more air. That's why this isn't a "choke", rather an ENRICHENER. It adds fuel, not cuts off air the supply (butterfly) making the mixture richer.

Make sure to clean the enrichener port out well with carb cleaner, and clean the pintle well, also.

 

One thing you may want to do, is to remove the air fuel mixture screw, and clean and inspect the tip. In the screw passage, there's a brass needle screw, a spring, an o-ring and a washer. Note the order they came out in. Note if there's any damage to the screw as it's thin and fragile. Clean screw and replace all removed parts in the order they were removed. Kits for rebuilding will come with a new o-ring. Replace it if removed.

dave, one question. i have remove the air fuel mixture screw but i didnt found a washer?

so i buy a new rebuilding kit but i dont know the order. which is the right one.

-screw, spring, washer, o-ring

-screw, spring, o-ring, washer

-screw, washer, spring, o-ring

could anyone help me?

thanks and all the best pat

 

Once the carb body and bowl are cleaned and polished, and the carb throat is polished, I'm ready to reassemble. In the case of this carb, the fuel inlet was plastic. This needs to be replaced. The old elbow id removed and a CV-Performance brass elbow is put in its place. Refer to the STICKY on elbow replacement.

The accelerator pump 3-screw cover is removed and the diaphram is inspected. Keep in mind that the diaphram can delaminate and peel apart. If you see this, regardless of being only one side, then replace it. There's a small o-ring in between the cover and the carb bowl that needs to be replaced when removed. In this case, I also replaced the hardware.

The emulsion tube, main jet, pilot jet, needle and float are replaced. Keep in mind, when removing the float pin, THE PIN IS REMOVED FROM THE LEFT TO THE RIGHT, IF THE PIN TOWERS ARE FACING YOU AND THE FLOAT IS FACING AWAY FROM YOU. If you try to force it the other way, you'll break a tower and the carb is now JUNK. There's an ARROW pointing towards the way the pin is to be removed.

Once all parts are installed, replace the bowl, accel pump bellows, accel pump actuator shaft and 4 screws.

 

Replace the slide and diaphram. I polish the slide, and bevel the leading edge for better air flow. Make sure on reinstall, the lip of the diaphram fits into the upper housing groove, or you'll tear it and it'll leak. It's a $60 part. Keep that in mind. As the cover is placed on it, you can push the rubber end back into the groove with a small screwdriver. As the lip seats, you'll see the cover meet the carb housing.

 

Install your main jet needle, the spring seat and the spring. I used an XL needle for this build as it works well with giving good midrange fuel with no bog. If your engine is stock, install the needle (XL PT# 27094-88). FOr larger engines. cammed engines, I use a .050" shim under the needle to add just a touch more fuel.

Can be seen in throat, into main housing:

You can either install a DynoJet spring which is shorter and a lighter spring rate, (8.8 onces for 3" compression and 5" long VS stock which is 12.5 onces for 3" compression and 5.5" long) a stock spring, or take a stock spring, cut off 3 rings from it, and your slide will react faster, giving similar results as the DynoJet spring.

Now that all your parts are inside the top of the carb, the cover can go back on, sa can the right side cable cradle.

 

Install your chokepintle and spring back on the cable, and reinstall back on the carb. GENTLY tighten the plastic nut back into the carb housing.

I generally set the air/fuel screw 2 turns out to start. This carb is set up for a Big Twin, with a 190 main, an XL needle shimmed .050", a 48 Pilot jet, new accel pump diaphram and a stock diaphram spring, and no drilled slide air-bleed hole.

This is your completed carb:

 

OUTSTANDING, Dave!

Now I'm REALLY glad you got that carb. Well documented, this ought to help a lot of people out. Thanks for posting, man.

A LOT of gasoline has gone through that carb. And now it looks better than new.

 

Excellent Dave! :thumbsup

What's the polishing process you use?

 

oh boy... you shoulda never asked that! Trade secret:cussing.. back away from the windows and close the drapes...:laugh

 

I see what you mean Dave, that little brush really works well. Looks like a new carb....:thumb

 

Yeah.....I'm fuzzy as a peach about the job it did, Phil. Offer still stands....!!

 

My 1991 FXSTS OEM cv carb takes a 27576-88 float , I am unable to find one near by, but can order a float from a 1992 FXSTS with part number 275-92 . Do you know if they interchange ?

 

Mine musta been before you perfect this method...:think:cussing:bluduh

 

Excellent thread Dave.....there were a few different XL needles used over the years.....any particular needle that you like the best for an 80" / EV27 / 9.5CR setup ....thanks

 

This is what he posted.....

If your engine is stock, install the needle (XL PT# 27094-88). FOr larger engines. cammed engines, I use a .050" shim under the needle to add just a touch more fuel.....

 

Sorry......

 

Hahahaha.....It's ok, Phil. I posted at the same time you did.

 

P.S. i ordered both parts we discussed earlier....an a bottle of Jack. fer installation purposes...:thumbsup

 

Thank you Dave and Zeta....

 

Thanks for this thread Dave!!!

My carburetor education continues:rollin:rollin

So, with all of your carb knowledge, do you think you could tune a bike without a dyno as well as someone who had one???

 

Jetting is like math: Engine mods = fuel necessity. Even though I may recommend certain jetting, a Dyno tune will prove or disprove a bench tune, and adjustments can always be made to gain that liitle bit more of torque or power.

I only get the bike within 90-95% of the needed range. I'm sure if I suggest a 48/185 set up with a .050 shim on an XL needle or, or use various other needles, there's always a slight improvement that could be made, that's only going to be found on a Dyno, using a gas analyzer.

Will the rider actually "feel" the difference in that change. Maybe....maybe not.

If it wasn't so expensive... I'd recommend Dyno tuning to everyone. It's amazing how we assume any mod we do with GAIN us power/torque, and then to see how some mods actually cause us to LOSE power and torque.

You'll really get no better tuning then to have it done by an exact science, with real world results, not trusting your "Ass-Dyno".

 

Congrats Dave, great informative thread.

 

It still amazes me the power numbers some of these little engines can get that like you said was pie in the sky many years ago. Big v8's back in the day got 400 hp if they were really good.

Now, a really powerful v8 can get 600, and supercharged it can get more.

Gotta love technology

 

2012 Camaro. V-6. 300 Hps...........

A far cry from the V-6's of 1980's that couldn't pull a sick whore off a toilet seat.

 

So, how much power does it actually take to pull one off the toilet seat!!:rollin

I guess at least 300hp lol

 

180 HPs if she's addicted to crack, lost her pimp and has at least 4 prostitution convictions, and is currently on parole....... There's a flow-chart somewhere to figure this out.

 

Great description Dave, thanks. Can you tell us which way the the needle jet above the emulsion tube goes, since it likes to drop out when you're not looking, when you take the emulsion tube out. I think it goes in with the longer section up, so the larger hole is up as well. Can you confirm or correct that?

 

Great description Dave, thanks. Can you tell us which way the the jet needle goes, since it likes to drop out when you're not looking ,when you take the emulsion tube out. I think it goes in with the longer section up, so the larger hole is up as well. Can you confirm or correct that?

 

The needle goes in, from the slide diaphram, tip first, down into the carb throat, then into the emulsion tube.

If you simply take the emulsion tube out, the sleeve can drop out, but the needle CAN'T come out that way, as it sits in the diaphram base, as it rises and falls with the slide diaphram.

You can see, with the slide diaphram removed, the needle comes out with it. It can't slide downward any father, due to the "hat" on the end.

You can also see the "seat" (Bright silver) in the carb throat that the needle slides into, which is kept in place by the emulsion tube. (Needle Jet)

The only possible way a needle could "drop out" after removing the emulsion tube, is if it were a DynoJet needle (with a clip to adjust height) that the clip came of of, allowing the needle to pass through th diaphram hole.

 

I think he was referring to the needle jet. If you take the emulsion tube out it can fall out.

From what I understand there is a big opening and a little opening. The big opening points up into the carb throat and the little opening goes toward the emulsion tube.

 

I read his post again and see why I answered the way I did....

Great description Dave, thanks. Can you tell us which way the the jet needle goes, since it likes to drop out when you're not looking ,when you take the emulsion tube out. I think it goes in with the longer section up, so the larger hole is up as well. Can you confirm or correct that?

I see, now.

The needle is what I was refering to.:thumbsup

Correct....The "needle Jet" can fall out. Small end down, larger end up.

 

I'm getting old and confused. I was referring to the needle jet, not the jet needle. I even carefully edited my original post from "needle jet" to "jet needle" to make matters worse.

Thanks for sorting me out Dave and Cobra. Small end down, big end up, I'll check my carb tonight, as mine did fall out, and I think I got it right, but who knows.

 

Damn good info. I put a spacer under my needle a year ago and also went up a jet size. I didn't see much if any power increase, but definitely saw my gas mileage drop. I plan on going back to the stock set up this weekend.

 

Depending on the needle, you will. With the right needle and height, the midrange lean issue becomes nonexistant.