Mikuni carburetor

[xboxrox]

yeah float pins are usually loose as in my experience. but once installed the body stops them coming out

Thanks tortron, you made me feel like a

[xboxrox]

MAJOR DISCOVERY ~ PROGRESS ~

?? DISCOVERED ?? WHY OUR TRUCK WON'T START & DIED A SLOW DEATH TO THAT POINT ~ THE CARBURETOR FLOAT IS ABOUT 1/5 to 1/4 FULL OF FLUID, I JUST NOW GAVE IT A SHAKE... I LOOKED AT THE NEEDLE & SEAT, THEY BOTH LOOKED PERFECT... FUEL BOWL WAS DRY WHEN WE PULLED THE CARB TWO DAYS AGO; SO I BET THAT FLOAT COULD HAVE HAD EVEN MORE FUEL INSIDE AS IT WAS RIDING SLOSHING WAVES OF GAS..? JUST VACUUM TESTED THE NEW NEEDLE & SEAT 'n FLOAT ASSEMBLY ON MY REBUILD FRANKENSTEIN; PASSES EVERY TIME :^) ALSO APPLIED 12 VOLTS TO BOTH THE J/Y BVV ELECTROMAGNET & MY ORIGINAL; THE ORIGINAL HAS A LITTLE STRONGER PULL & IT WILL GET USED IN THE MONSTER... PLAYED PUZZLE WITH TOP & BOTTOM THROTTLE BODY GASKETS; ALMOST GOT TRICKED BY MINOR THROTTLE BORE SIZE DIFFERENCES... MIKES'S CARBURETORS SUPPLIED FILTER https://www.carburetor-parts.com/Mikuni-Solex_c_28.html

[geezer101]

Nice sleuth work xbox The fuel float full of crusty fuel - not so good...

[85Ram50]

Bummer they don't include a new float in the rebuild kit. They do with Weber and the one I got for my motorcycle. I thought they did with all kits.

[xboxrox]

Bummer they don't include a new float in the rebuild kit. They do with Weber and the one I got for my motorcycle. I thought they did with all kits.

I bought a replacement float from RA 'n it would probably work but it's a rather different configuration & as such, the float level measurement is taken a completely different way than the factory method (strange...) but I'm using my original float... It's a darn good thing member yamahauler sent me an FSM & member 4cylinders sent me a Mikuni carburetor in parts and a darn good thing parts puller Allen in Roseville, CA sent me the PicknPull 1985 California emissions Mikuni ~ without all these spare parts and a 2nd Mikuni carburetor; I do believe it would have been somewhere between tremendously difficult & darn near impossible for me to rebuild the Mikuni carburetor... With little to no practice and having to wait several months for parts, the memory fades with the large amount of time between disassembly & reassembly... There are four letter words that describe the situation better than my story above..!

BACKGROUND NOTES:
1) Bad float & improper float adjustment caused flooding of an otherwise nicely rebuilt Mikuni (PicknPull carb)
2) My original Mikuni was a one barrel carb, not anymore, if it runs, it should work as a 2 barrel carby
3) My advice about carburetors, buy a rebuilt Mikuni 'n bolt it on OR modify with a new Weber (in that order..!)
4) Unless you have parts, tools, patience & experience, rebuilding the Mikuni is not my recommendation...
5) Is it just me..? Or, will the ball bearing in the fuel bowl drop out of place if the carb is turned upsidedown..?
6) In regards to #5 above (if yes) then the carburetor top needs removal again..! Yikes..!
7) In regards to #5 & #6 above; does the float prevent the large ball bearing from falling out of place..?
8) How would a person (perform a test) to get the answer in regard to #5, #6 and #7 above..?

Get the Wife to do the Work..?

[geezer101]

Bummer they don't include a new float in the rebuild kit. They do with Weber and the one I got for my motorcycle. I thought they did with all kits.

You don't get a choke release assist diaphragm (there are a few different types which is helpful too...) and some kits don't even have the accelerator pump diaphragm and gaskets in them (straight up useless as they are prone to failing). A 100% overhaul kit would have a new secondary actuator servo, a wax pellet for the choke, the choke assist and gaskets for 3 different 32-35DIDTA carb variants and the replacement fuel bowl float (say hi to a $500 rebuild kit) but they don't make them as nobody would buy them

[FMS88]

I bought a replacement float from RA 'n it would probably work but it's a rather different configuration & as such, the float level measurement is taken a completely different way than the factory method (strange...) but I'm using my original float.

BACKGROUND NOTES:
5) Is it just me..? Or, will the ball bearing in the fuel bowl drop out of place if the carb is turned upsidedown..?
6) In regards to #5 above (if yes) then the carburetor top needs removal again..! Yikes..!
7) In regards to #5 & #6 above; does the float prevent the large ball bearing from falling out of place..?
8) How would a person (perform a test) to get the answer in regard to #5, #6 and #7 above..?

I have a Hygrade FL87 float that's of no use to me. It's yours if you want it.
Regarding the ball in the float chamber, it sits in the channel in the bottom of the chamber shown in the first picture of your first post on 9/11/20. The ball is kept in the channel by two stamped strips of metal held in place by the two pins and screw/washer at mid-bottom of the chamber. In the event your grocery run takes a disastrous and unexpected turn, the ball pushes on either of the metal strips which in turn contacts the float stopping the fuel flow. I wouldn't worry about omitting the ball and definitely delete it if you don't have the metal strips. I've disassembled several remanufactured carbs and none of them had the ball and metal strips. Unless you do some serious 4-wheeling, omit it. Probability is in your favor.

[xboxrox]

Thanks fellahs for all this seriously helpful information...

We almost got to the point of connecting the battery for a try at starting the truck last night...

UNTIL I tried placing the air cleaner rubber gasket on the carb; it was missing the ring 'n 2 screws...

Hiked back to the room to get the ring and Oh Boy, it felt like I just received some really bad news...

There in my parts basket were parts #68, #69 and #70 for both primary & secondary throttles..!

At least we did not contaminate things with gasoline or coolant...

It won't require a complete teardown but the carb top piece needs to come off again; I made a note of 5 other things to do as well...

See, Stop is Good Progress..!

Of special interest to me was finding a bunch of gooey electrical silicone inside the female half of the TPS connector... THIS might be the cause of weird engine running, hope so... Will clean it out even more on our 2nd carb install try...

Best part of last night was neither me nor wife got upset about the forgotten parts discovery ~ she complimented me for not getting angry & said it's your 1st try @ fixing this Mikuni thing, no surprise you made a mistake... Just don't drink too much beer when working on it, OK..?

Confession Complete & Staying Safe 'n Smoke Free in Hawaii --
Aloha George

[xboxrox]

I have a Hygrade FL87 float that's of no use to me. It's yours if you want it.
Regarding the ball in the float chamber, it sits in the channel in the bottom of the chamber shown in the first picture of your first post on 9/11/20. The ball is kept in the channel by two stamped strips of metal held in place by the two pins and screw/washer at mid-bottom of the chamber. In the event your grocery run takes a disastrous and unexpected turn, the ball pushes on either of the metal strips which in turn contacts the float stopping the fuel flow. I wouldn't worry about omitting the ball and definitely delete it if you don't have the metal strips. I've disassembled several remanufactured carbs and none of them had the ball and metal strips. Unless you do some serious 4-wheeling, omit it. Probability is in your favor.

I got the exact same float as a replacement but will stick with the original float, thanks FMS88...

[85Ram50]

That is probably Di-electric grease which is meant to prevent oxidation and connectivity breakdown that comes with as you probably know
You are doing better than I would.

[xboxrox]

That is probably Di-electric grease which is meant to prevent oxidation and connectivity breakdown that comes with as you probably know
You are doing better than I would.

Nah no better, I seen your work methods 85RAM

That dialectric grease is weird, the label says it conducts electricity... A good thing for turn signal & stop light bulbs BUT no so good on spark plug wires or computer control sensors... It can foul up the TPS signals to the computer...

LIVE & LEARNING ME

[geezer101]

Yeah you need the opposite like lanolin grease. I created an ignition problem by using a conductive grease on my spark plug boots - it misfired like it was possessed

[claych]

xbox,
With respects I need to correct some of Your info.
Dielectric grease is not conductive, as such if a sensor connector is filled with same there is a good chance
sensor input, ground, or v/ref could be skewed. ( sensor circuits are 5v & usually <.005 ampere ).
As far as plug boot usage , all I ever used was dielectric , 20 plus years as dealership driveability tech
literally hundreds of plug and wire changes.
Perhaps the tube label your looking at is 'thermal grease' ?
Thx.

[xboxrox]

xbox,
With respects I need to correct some of Your info.
Dielectric grease is not conductive, as such if a sensor connector is filled with same there is a good chance
sensor input, ground, or v/ref could be skewed. ( sensor circuits are 5v & usually <.005 ampere ).
As far as plug boot usage , all I ever used was dielectric , 20 plus years as dealership driveability tech
literally hundreds of plug and wire changes.
Perhaps the tube label your looking at is 'thermal grease' ?
Thx.

Yes I better read that label again -- I bought the large dispening tube and used a big glob of it in the spark plug boots 2 years ago when installing new wires & plugs -- the engine ran like crap after that -- ?? So after I cleaned off the dielectric grease it ran good like it had new plugs & wires... On the carb TPS (throttle position sensor) I remember injecting a big glob of it into the TPS connector after Vernon had super glued my original carb's cracked phenolic body... On startup the truck ran crappy not smooth like before -- next was gas still leaking bad glue for gas -- rcvd J/Y carb & installed the truck ran weird crappy still BUT NO gas leaks -- so, I'm gonna try paint thinner to clean out that goop as electrical contact cleaner spray & wiping does not get it out -- I want it clean NO GOOP when we try starting it with this rebuilt carb --

My Lenovo T61 laptop has FAN ERROR -- so soon I will try my hand at electronics rebuilding

[85Ram50]

I remember injecting a big glob of it

Well there's your problem.
It is meant to be a light coat. Using it on plugs if there is too much it can cause the plug wire to pop off the plug from fully seated and ditto the distributor cap. Yes it happened to me.

[xboxrox]

REBUILT MIKUNI INSTALLED

Engine cranked but no pop sputter or trying to start -- I hope the battery will have enuff omph left to try with starting fluid... I remember mechanics getting this truck running when we 1st bought it -- sprayed starter fluid & cranked a bunch of times before it finally began to fire... I think they even dumped some gas in the carb...

[xboxrox]

Well there's your problem.
It is meant to be a light coat. Using it on plugs if there is too much it can cause the plug wire to pop off the plug from fully seated and ditto the distributor cap. Yes it happened to me.

You're right on both counts -- it is non conductive & directions say use sparingly -- I thought dielectric grease would improve a connection but it does just the opposite... I injected a pea size amount of it into the spark plug boot BUT I'm going back in to remove it to achieve a better electrical connection to the spark plugs...

[xboxrox]

Rebuilt Mikuni installed but truck won't start or act like it wants to start... Used tablespoon of gas or 3 seconds spray of starter fluid one or the other 8 good tries..! Battery cranking good & good spark at the plugs... Eng front cover has marks 10BTDC 0 10ATDC -- no mark or notch on crankshaft pullys... Will have to remove # 1 spark plug & find TDC on compression stroke... <--- how is that done without removing rocker arm cover..? Thumb on sparkplug hole or buy a compression gauge..? Truck not running or started for 3 months, maybe it needs oil fog sprayed into the cylinders not just for lube but to ensure having compression..?

We will be very sad to let this truck go... But we need transportation not a never ending class in auto mechanics with us supplying the school with tools...

[85Ram50]

The mark on the balancer is one line full width, indented. You might be able to feel it if you cannot see it. I mark mine with a silver sharpie when I need to see it. Is gas pumping through the carb?
To find TDC I use a tissue to watch as I turn for the compression stroke. It will blow the tissue, then I put a screwdriver in the plug hole and hold it loosely. When the piston gets to the top it will start to go down and you will feel it. There ya go.

[xboxrox]

Thank you 85Ram50 the tissue idea is trick, I don't think my 3/8 socket set will fit the crank bolt, so I either learn how to use a screwdriver to short the starter selenoid wires or use the ignition key -- I don't plan on spending $25.00 for O'Reilly to sell me a remote starter switch... OReillys is charging my battery now, the battery has plenty power this is just extra step -- I don't know if the fuel pump has gotten fuel to the carb -- I thought after checking ign timing that I would remove the carb fuel supply hose from the fuel pump barb -- I rented a compression tester from O'Reillys and bought a spray can of fogger fogging oil -- the cylinders could use some lube I bet & as well as checking ign timing might as well do a compression test -- there might be more to this than a previously flooding carb -- ? -- if the balancer has a line to mark TDC I will be super suprised nothing there

[85Ram50]

I think the crank is a 17mm. If you are removing the plugs any wrench that opens big enough will work, it turns pretty easily with the plugs out. My 3/8 drive turns it easily. A remote starter or bumping the starter will move it to far too fast. I should have stated TDC Compression stroke, as there is the exhaust stroke 180 out that will feel the same so making sure the rotor is pointing at #1 helps. It ran so you could not have been too far out when you parked it. I thought you just wanted to improve annoying things it did because of the carb being old. You need more then a few teaspoons of gas. At least use tablespoons.

[camoit]

I always just put the truck in reverse gear and released the parking brake. Then pushed on the bumper with my knee to rotate the engine over.
if the truck has a belt. The timing mark is below the flat of the head. Many people get it off 1 tooth because they go off the flat of the head.

[xboxrox]

I need these details, thanks guys... The timing mark I'm searching for is on the fan belt pulley somwhere, this truck has two V belts alt & pwr steering -- I'm gonna look at the pulley lip closest to the engine (Dr. geezer's advice)

Darn, my resident apt mgr just texted me if I got the truck running yet or if I wanted to sell it..? Howz that for moral support..?
Going now to get my fully charged Interstate battery -- O'Reillys charged it for free... They have a $26.00 + tax remote start switch -- now I'm confused if it will help me spin the engine with spark plugs removed to inject the fogging oil I bought yesterday -- all this extra stuff is beyond just starting the engine after a carb rebuild BECAUSE before we got it parked back at the apt Vernon could not get it to start & neither could Sam @ his Windward Muffler repair shop -- not any responce even with good spark starter fluid & gas stopped on carb -- something is amiss -- Dr. geezer has a few more things for me to check as well
ALOHA George

Ign timing check
Spark plug wire routing check
Compression test
Test each spark plug separately for firing
Check proper fuel line connect to carb
Check gas tank level -- dash gauge reads 3/8
Remove fuel pump to carb inlet hose to check if fuel pump is pumping gas
Yada Yada Yada
What then if still NO RESPONCE when trying to start..? Just fishing for more ideas that hopefully won' t be needed in the near future...

[claych]

xboxrox,
Remove the fuel inlet line to the carburetor, fab up a remote reservoir & hose, attach to inlet--- fill the float bowl ---

Pump pedal thrice ,start & report back.

Thx

[85Ram50]

I misled you Xbox. I was picturing my Dakota when I told you about the mark. Here is a picture of mine. The white spot is the notch on the inner pulley closest to the timing belt cover. It is a notch so you should be able to feel it.