Carb Washer Shimming

[VerntureVet]

I Read this in another post maybe here. People talk about enriching there carb after modding the exhaust (baffle removal or open pipes)

 

The best way to correct lean or rich is a rejet and exhaust analyzer but for those who don't want to tackle digging deep into the carb this may help you get threw until you do it the correct way.

 

On another note this same MOD has been said to improve throttle response on stock and bike with MODed exhausts.

 

Correct me if I am wrong.

What you are actually doing is retracting the Jet needle out of the Jet some. This should result in a faster opening main or even possibly a partial open main jet I am not 100% sure. What I am sure of is that I knocked all but the forward most baffle in my stock mufflers and even that one I left with 4 X 3/4in holes. Naturally after that I experienced a sluggish motor. After doing this the bike woke up like a cat in a thunder storm.

 

I would be happy to edit this to reflect accuracy feel free to educate and correct.

 

So lets get to it.

 

Gain access to your carbs by removing a many covers as you need to get in there with a screwdriver and tamper proof socket.

 

I could not find my tamper proof socket set so I used a rotary tool to grind off the stud and get it off with a standard one.

 

 

When you get to the last screw hold the cover there is a big spring that will push the cover off.

Also note the O-Ring

 

This would be a good time to consult the service manual to check the length of the spring. I didn't get that into it rather I just stretched the longest one out 1/2in and the stretched the rest to be the same length when sitting on the table. I am sure there is a spec and you really should not cut corners like I did unless you want to get back in there and do it again.

 

 

Now carefully work the diaphragm loose and remover the assembly from the carb. Head to a nice clean work area so you don't loose any small part.

Take care not to damage the needle or diaphragm.

 

Look down inside and you will see a (nylon?) nut. Use a flat screw driver and remove the nut. Take care as there is a spring under this nut also.

 

 

Once the nut is off store the spring in a safe place unlike me who just laid it on the table and ended up looking for one for almost an hour.

 

Remove the needle gently you will find it has a (nylon?) ring, a c-clip, and a Washer on the shorter end.

 

 

Slide off the Nylon ring and the washer. Then put the washer back on from the point end of the needle and reinstall the nylon ring. You then want to install a new washer in place of the old one. The original washer is just the right size on all 4 carbs trust me I MICed them however the ones I installed had a slight variation in thickness. Its function was to keep the needle from sliding thru the spring so just moving the washer is not enough you need one.

 

NOTE THE STUD ON THE NYLON RING

 

 

When you put the needle back in be sure the stud on the Ring seats in the hole.

 

Reinstall the small spring and put the nut back on.

 

 

Now would be a good to do clean things up. If your needle is dirty you can buff it lightly with aluminum foil to clean it up. Take care not to damage or bent it. The entire needle does not have to be clean the most important part is the inch or so on the pointed end.

 

 

OK now work in reverse and put it all back together. Rinse and repeat for the other carbs.

[videoarizona]

Robert,

 

This idea has been around a while. I remember this from another bike years back. But your pics and explanation actually made sense to this brain dead and tired guy!

So...Thanks!

david

[garyS-NJ]

I'm working on an '86 xvz13 and on the right bank carbs notice the rear needle is protruding from piston about 6mm more than the front.. Is this right?

 

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[MiCarl]

For some reason Mikuni thought that needle needed a washer on top of the E-ring.

 

I'd leave it and add another washer below the E-ring.

[garyS-NJ]

The difference is about 6mm which sounds like more than,one washer. But ill get all four measured and see if I can set them the same and try it.

 

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[flyday58]

Did this on my '83 to lean out the carbs for high-altitude ops where I live. Bike runs much better. Big shout out to Herr Puc-enmeister for the help.

[cowpuc]

Did this on my '83 to lean out the carbs for high-altitude ops where I live. Bike runs much better. Big shout out to Herr Puc-enmeister for the help.

 

Right back at cha Flied Lice :thumbsup::thumbsup:,,, amazing what a difference fifty cents worth of nylon washers can make aint it

Keep em flying brother!!!

[cowpuc]

Might add for anyone else reading this thread,,, dont forget to check for pinholes, check for ease of movement on the slides, check for that sneaky little o-ring under the diaphram cover and DOUBLE check for diaphram alignment in the carb body before you button er up!! The quality of work you do today may result in a worthy sync job tomorrow

[garyS-NJ]

The needle plastic thing nub wasn't seated in the slider. All good now. Thanks again everyone!

 

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[CaseyJ955]

The needle plastic thing nub wasn't seated in the slider. All good now. Thanks again everyone!

 

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Glad its sorted. Let the good times roll!

[yamagrl]

The needle plastic thing nub wasn't seated in the slider. All good now. Thanks again everyone!

 

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Do you mean that you have found the resolution to the problem you mentioned in Main jet needles different lengths?

 

Did this help?

First things first... I'll betcha a dollar that they are not seated properly.

 

 

1. Just take 'em apart, then make certain that the white spacer is in place against the cir-clip. Drop the needle with the spacer and cir-clip into the slide.
   
2. While holding the slide in one hand twist the needle while applying a gentle outward pull on the needle. When it finds it's place hold it firmly and insert the washer and spring with something such as hemostats . Then put that plastic nut on. This can be a bit tricky.
   
3. Do all four slides.
   
4. Measure
   
5. Refer back to "First things first"
   
6. ​Send dollar.
   

[garyS-NJ]

Yes, I was thinking about that dollar when I measured total needle length 50 mm, saw no extra clip grooves in the needle, and measured the needle after dropping it in. Still don't know how that little nub added up to all that difference. But she's running pretty good now and I'm gonna check carb sync today.

 

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[yamagrl]

Yes, I was thinking about that dollar when I measured total needle length 50 mm, saw no extra clip grooves in the needle, and measured the needle after dropping it in. Still don't know how that little nub added up to all that difference. But she's running pretty good now and I'm gonna check carb sync today.

 

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Sometimes a dollar goes a long way! Put it in your "Pay it Forward" pocket.

 

Glad you got it running. These carbs can be finicky about certain things. It's almost like turning a light on or off... when it's correct they work properly, when they aren't correct they don't and there is usually little middle ground.

 

[garyS-NJ]

Yes like getting adequate fuel and proper breathing. My makeshift fuel delivery found Ng and This '86 is way more sensitive than my '84 interns of having the airbox on and closed..

 

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[CaseyJ955]

Yes like getting adequate fuel and proper breathing. My makeshift fuel delivery found Ng and This '86 is way more sensitive than my '84 interns of having the airbox on and closed..

 

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If the 84 didnt care so much it may have been on the rich side. If jetting and float level are right then it will feel the absence of the airbox. I know when I did my VMX1200 and went with a free flowing airbox modification I had to also install air correctors in the carbs to keep things proper.