Carb rebuild Part 1 (PICTURE RICH)

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naughtyG

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As I just cleaned / rebuilt my carbs, I thought I'd document the process, especially the re-assembly since we already have plenty of instructions here as how to take 'em out and apart.

Because I took a lot of pics and didn't want this thread to take 4eva loading every time you open it, I divided it into multiple parts.

Here's Part 1 - starting with my dirty 'ol carb:

Starter plunger has been removed, but as advised by Mark, I didn't remove the housing as it wasn't leaking
P1030741.jpg


looking at the slide opening - you can see my (very damaged by POs) PAJ2
P1030742.jpg


Other side view showing removed coasting enrichener and all the dirt from a leaking fuel bowl
P1030743.jpg


Looking into the empty fuel bowl - float, needle valve, jet block and needle jet all removed
P1030745.jpg


Time to give the outside a good clean, I used Purple Power and a clean new paintbrush
P1030746.jpg


then blew it all dry with compressed air
P1030748.jpg


Then I penetrated every single orifice with the Carb Cleaner straw - PAJ1 hole first
P1030749.jpg


air bleed hole
P1030750.jpg


PAJ2 (only thing I could not remove)
P1030751.jpg


Air/Fuel screw hole
P1030752.jpg


the hole next to it
P1030753.jpg


starter plunger orifice
P1030754.jpg


Every hole under the jet block - you can see how some are dirty
P1030755.jpg

P1030756.jpg

P1030757.jpg

P1030758.jpg

needle valve seat

P1030759.jpg

fuel bowl bleed exit
P1030760.jpg

holes behind the throttle in the venturi
P1030761.jpg

P1030762.jpg

coastng enrichener
P1030763.jpg

vacuum to the CE
P1030764.jpg


And then blew every one of these holes with compressed air and repeated the process. No more dirt in my carb - and did that for all four of them. :eusa_dance:
 
Carb rebuild Part 2

So now I have a lovely clean carburetor body - in and out
P1030765.jpg


P1030766.jpg

P1030767.jpg

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Here are all the small parts removed from the carb:
1. Float
2. Pilot Air Jet 1
3. Needle Valve with spring
4. O-ring (from under slide body)
5. Float bowl purge screw with o-ring
6. Rubber plugs
7. Pilot Jet
8. Main Jet
9. Main Bleed Pipe
10. Jet Block
11. Needle Jet
12. needle jet Retaining Screw and Washer
13. Air/Fuel Mixture Screw, Spring, Washer and O-ring
14. Cap, Spring and Starter Plunger
15. Coasting Enrichener and Spring
skitched-20081111-230417.jpg


Starter Plunger was a little gummed up and that wouldn't come off with carb cleaner, so I use some 1500 wet/dry paper to lightly clean it
P1030771.jpg


Also used this on the Coasting Enrichener
P1030783.jpg


and on the fuel bowl bleed screw. Checked the o-ring on it - all good.
P1030784.jpg


Fuel Bowl cover with old flattened gasket and all the dirt from leaks and sediments
P1030772.jpg


All of the above all cleaned up!
P1030775.jpg


Here are all the parts I renewed with their Yamaha part numbers - thanks Gary McCoy for a great deal as usual!!
skitched-20081111-233529.jpg


Ready to start re-assembly - see'yall in Part 3 :punk:
 
Carb rebuild Part 3

I started by refitting the fuel bowl bleed screw
P1030788.jpg


Fed the needle jet back in from the inside
P1030794.jpg


Holding it from behind, slide the new o-ring on it
P1030795.jpg


the o-ring, once seated properly, holds the needle jet in place for now. Notice the way the groove in the needle jet is facing - there is a protrusion in the jet block that will slide on it.
P1030796.jpg


Next the new jet block gasket goes in, making sure the projections in the carb body (by my finger tips) mesh with the holes in the gasket:
P1030800.jpg


The pilot jet and main bleed pipe caught in a little foreplay action :rofl_200:
P1030801.jpg


Securing the pilot jet *using the right screwdriver for the job!*
P1030805.jpg


and the main bleed pipe
P1030806.jpg


Time for the first rubber plug - notice the flat facing the bottom
P1030808.jpg

same with the 2nd rubber plug - excuse the auto-focus of the cheap camera
P1030810.jpg


Both plugs fitted
P1030812.jpg


Sliding the jet block carefully over the needle jet
P1030814.jpg


Jet block in place - notice the needle jet groove facing down and the rubber plugs well tucked in
P1030815.jpg


Securing the jet block with its two screws - careful not to overtighten..
P1030816.jpg


Then refitting the needle jet brass screw and washer
P1030818.jpg


Main jet is going in next
P1030822.jpg


Using a magnifying glass to check that the needle valve is in good condition - it looked huge to the naked eye, honest! - but the camera didn't think so :confused2:
P1030823.jpg


Needle valve going back in carefully - easy to damage!
P1030827.jpg


There it is in place - spring opening facing up for the float tab
P1030830.jpg


Refitting the float
P1030831.jpg


In place with the tab in the spring
P1030832.jpg

Setting up the float level on the bench - hold the carb up so that the float's weight closes the needle valve, resting on it but without compressing the tiny spring behind the valve's nipple. Here it's a tad too rich:
P1030840.jpg


and here it's way too lean:
P1030847.jpg


Bend the float's tab slightly and carefully to adjust
P1030848.jpg


and here it's set just right. The way to tell - as per Mark's 'setting float levels on the bench' thread - is the circle on the jet block and the circle made by the float's shape are perfectly edge-aligned:
skitched-20081112-002236.jpg


fitting the new gasket to the fuel bowl cover - must press it into the grooves
P1030852.jpg


in place
P1030855.jpg


Sliding the cover over the jet block and under the vent pipe
P1030856.jpg


make sure it's sitting properly within the tabs on the body
skitched-20081112-003059.jpg


and secure it with its 4 screws - again, tight but not overtight!
P1030863.jpg


New o-ring on the main jet cap
P1030866.jpg


and in it goes, just tight enough with the 10mm wrench
P1030869-1.jpg


K, fuel bowl is sorted, this'll do for part 3!
P1030872.jpg
 
Carb rebuild Part 4

'Ere we go again - will this thread ever end? :biglaugh:

Coasting Enrichment diaphragm is going back in. Make absolutely sure the diaphragm is in good condition or replace!
P1030873.jpg


Rubber tab must fit in here
P1030874.jpg


Spring goes in next
P1030879.jpg


Make sure the spring fits properly over the cover's tabs! (I really need a manual focus don't I :bang head:)
P1030880.jpg


Hold the cover compressing the spring while fitting the 3 retaining screws
P1030881.jpg


There it is back in and getting tightened. Notice my bottom left screw is not OEM - will this devalue my bike? :rofl_200:
P1030882.jpg


Hold the nipple of the starter plunger tightly with the spring compressed and the cap over the end.
P1030883.jpg


Insert it into its housing
P1030884.jpg


Screw it in finger tight
P1030885.jpg


And tighten it with the 14mm wrench
P1030887.jpg


_____________________________________________________
******** INTERLUDE ********

CalvinSneeze.jpg


K' children, back to work...
_____________________________________________________

Let's put our PAJ1 back in
P1030888.jpg


the A/F screw complete - notice the order of things - spring, metal washer, o-ring. If you squint it almost looks in focus..
P1030894.jpg


going back home..
P1030895.jpg


and gets seated lightly, then back 2 1/2 turns as an initial setting
P1030899.jpg


At this point PAJ2 (seen in above picture looking quite sorry for itself) would usually go back in, but in this case it never came out.
Why didn't I take pics when doing the other 3 carbs :ummm::bang head:
Let's NOT forget our little o-ring, that we made sure was in great condition
P1030901.jpg


The slide goes in next, having double-checked the diaphragm was in good shape. I didn't disturb the needle this time, but if I need to go back to add shims, I will document it and add it here.

I cleaned the slide and diaphragm with WD40 just before mounting and lightly blew it with low PSI compressed air
P1030902.jpg


Making sure the rubber tab of the diaphragm fits in the recess provided for it
(top right)
P1030905.jpg


Then the spring goes in
P1030906.jpg


and make sure its other end fits around the cover's inner tabs
P1030908.jpg


Hold the cover in place and refit the screws. Mine have been replaced by stainless steel allen heads - nice and highly recommended.
P1030910.jpg


Checking the starter plungers move freely - pull on the nipple
P1030911.jpg

and let go, it should pop back in all the way
P1030912.jpg


checking the throttle is also playing nice - also a good time for a tiny drop of oil on its return spring
P1030913.jpg


and refit the bowl fuel bleed hose, making sure the bend in it makes it go toward the slide cover.
P1030914.jpg


And we're ready for part 5 :clapping:
 
Last edited:
Carb rebuild Part 5

One of four beautifully clean and thoroughly checked to be in tiptop condition carbs, ready for getting back together as a set
P1030916.jpg


As the first two carbs become a couple again, this little spring must be refitted between the throttle arms
P1030917.jpg


Here it is in place - I'm holding the carbs together
P1030919.jpg


The first holding plate goes in. This is actually the wrong plate - it goes on the other two carbs (3&4). The one going here has the throttle cable holder on it, but I could not find that pic. I fired my photographer.
P1030921.jpg


when reassembling carbs 3 & 4, there are two springs this time - one for each sync screw. Fiddly, but do-able, and then fit the plate pictured above.
Please note that at this time, the plate's screws are only tightened very lightly. This is because once everything's in place, they will get re-tightened and a drop of thread lock is to be added.
P1030922.jpg


The chrome side-plates are next, but we will give'em a little polish first
P1030923.jpg


Here we go
P1030924.jpg


again I only pre-tighten these screws lightly at this time to make sure everthting gets a chance to get nicely aligned.
P1030926.jpg


We can feed the bleed hoses back into their holders now
P1030927.jpg


The fuel hose T-piece is going back in
P1030930.jpg


and let's make sure the spring clips are on and tight - I had to bend mine in a little to tighten them again
**quick correction, so you don't make the same mistake as I did: my fuel T-hose is the wrong way round - the shorter end should be at the bottom in these pics!**
P1030931.jpg


I put a little grease on the carb sync screws before refitting them with their springs
P1030933.jpg


again this is a bit fiddly for my big paws..
P1030932.jpg


Once threaded, it's a lot easier with the (appropriate) screwdriver!
P1030935.jpg


Let's squeeze that second one in
P1030936.jpg


initial tightening - I just looked at the throttle plates inside the venturis and made sure they were close, in the bulk part
P1030937.jpg


now we can re-assemble the two banks
P1030939.jpg


Let's do it in Part 6!
 
Re: Carb rebuild Part 5

I hope you are able to clean your fingers as well as them carbs :rofl_200:
 
Carb rebuild Part 6

First thing is the throttle link. It has two plastic washers and a circlip:
P1030943.jpg


I greased the link a little first where it rotates
P1030945.jpg


Then it goes on, one washer, linkage...
P1030946.jpg

...2nd washer, circlip
P1030949.jpg


I popped the circlip in place with my fingernail
P1030950.jpg


Let's re-attach the fuel link
P1030952.jpg


See it bending? It's the wrong way round! :doh:
P1030953.jpg


Next the Choke linkage goes back in. This is the trickiest part - it went in and out a few times to say the least.. Make sure the spring is fitted to the right-hand shaft first!
P1030954.jpg


This is just to illustrate the entry points. To the left:
P1030957.jpg

and to the right:
P1030956.jpg


Here's the trick: see how these four pieces look? They are ever so slightly different, and notice the plastic collars
P1030959.jpg


Now here's the deal; the bottom left is the straightest one, the other three have more of a bend in them. In order to be fitted properly, the first one (bottom left) must be engaged over the starter plunger nipple before the shaft is inserted, and then the plastic collar before the shaft enters the carb body
P1030965.jpg


There the shaft goes in with #1 in place
P1030966.jpg


On the right-hand side, the order is shaft / collar (facing the other way round) / fork
P1030968.jpg


I actually had to add another washer between the collar and the first right-hand fork (arrowed) to make my whole starter linkage function properly
skitched-20081112-033522.jpg


Next is the second left fork - insert the collar in the body hole behind, engage the fork on the plunger nipple, then insert the shaft through
P1030970.jpg


Finally, the second one on the right: collar in, fork over nipple, shaft last
P1030971.jpg


Woohoo! last one in. Note the hole in the shaft facing the screw. You will need to rotate the right shaft linkage for this hole to face the right way, and also rotate the right way when depressing the choke lever!
P1030972.jpg


Tighten all four screws and check operation. You may need to bend some of the fork tabs slightly to compensate for shaft and linkages wear and elasticity. I believe you want all four plungers to come out by an equal amount when depressing the choke lever, and that requires some adjustment unless you really paid better attention than I did to which fork was where..
P1030973.jpg


Once you're happy it's all working as expected, loosen each screw, add thread locking compound and re-tighten them one by one.

P1030974.jpg


As noted earlier, I had to add a washer to the right-hand shaft, because as the shaft spring exerted its pressure, it pulled the forks in a way that made them prevent the plungers from returning freely.

Finally, I refitted the locking screw to the Choke Lever. Notice the order - screw, spring, metal washer, plastic washer, then lever, plastic washer, metal washer.
P1030976.jpg


I stole one of the plastic washers for the right-hand shaft, so I had to fiddle with this as the choke lever wouldn't stay in place when depressed (locking screw couldn't be tight enough with only two plastic washers)
P1030977.jpg


After adding another metal washer behind the rear plastic one, I tightened it and it's fine
P1030979.jpg


Then I found two identical height wood block, and positioned then on the upright carbs
P1030981.jpg


I flipped the whole set over, and made sure everything was nice and flat (all the brackets were still slightly loose)
P1030982.jpg


Top view
P1030983.jpg


Having fixed it, I then installed the last brackets. That's when I noticed the fuel T-hose was the wrong way round!
P1030987.jpg


With everything in place, I then took every single bracket screw out one by one, added thread locking compound, and tightened them all to spec
P1030985.jpg


JOB DONE!! :clapping::eusa_dance::clapping::punk::clapping:

Now revert to Mark's thread for swapping main jets, and use reverse order to refit the carbs. Warm up, adjust idle, sync, then play with the A/F screws until it's absolutely perfect!

YAY :th_wine::th_fridaay::th_drink:


 
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