Carb rebuild Part 1 (PICTURE RICH)

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


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


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


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


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


then blew it all dry with compressed air


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


air bleed hole


PAJ2 (only thing I could not remove)


Air/Fuel screw hole


the hole next to it


starter plunger orifice


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




needle valve seat


fuel bowl bleed exit

holes behind the throttle in the venturi


coastng enrichener

vacuum to the CE


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






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


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


Also used this on the Coasting Enrichener


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


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


All of the above all cleaned up!


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


Ready to start re-assembly - see'yall in Part 3 unk:

Carb rebuild Part 3

I started by refitting the fuel bowl bleed screw


Fed the needle jet back in from the inside


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


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.


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:


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


Securing the pilot jet *using the right screwdriver for the job!*


and the main bleed pipe


Time for the first rubber plug - notice the flat facing the bottom

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


Both plugs fitted


Sliding the jet block carefully over the needle jet


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


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


Then refitting the needle jet brass screw and washer


Main jet is going in next


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:


Needle valve going back in carefully - easy to damage!


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


Refitting the float


In place with the tab in the spring

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:


and here it's way too lean:


Bend the float's tab slightly and carefully to adjust


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:


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


in place


Sliding the cover over the jet block and under the vent pipe


make sure it's sitting properly within the tabs on the body


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


New o-ring on the main jet cap


and in it goes, just tight enough with the 10mm wrench


K, fuel bowl is sorted, this'll do for part 3!

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!


Rubber tab must fit in here


Spring goes in next


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


Hold the cover compressing the spring while fitting the 3 retaining screws


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


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


Insert it into its housing


Screw it in finger tight


And tighten it with the 14mm wrench


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



K' children, back to work...
_____________________________________________________

Let's put our PAJ1 back in


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


going back home..


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


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


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


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


Then the spring goes in


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


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


Checking the starter plungers move freely - pull on the nipple

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


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


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


And we're ready for part 5 :clapping:

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


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


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


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.


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.


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


Here we go


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


We can feed the bleed hoses back into their holders now


The fuel hose T-piece is going back in


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!**


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


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


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


Let's squeeze that second one in


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


now we can re-assemble the two banks


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:


I greased the link a little first where it rotates


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

...2nd washer, circlip


I popped the circlip in place with my fingernail


Let's re-attach the fuel link


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


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!


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

and to the right:


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


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


There the shaft goes in with #1 in place


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


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


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


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


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!


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..


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



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.

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)


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


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


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


Top view


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


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


JOB DONE!! :clapping::eusa_dance::clapping:unk::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: