Mikuni carburetor

[xboxrox]

CHOKE COVER DISASSEMBLY & FASTENER TYPE:
(ALL 5 SCREWS ARE Tamper Proof Male Thread Metric M5 x 80) Tamper proof not required to reassemble choke cover; not sure why Mikuni used tamper proof fasteners on the choke cover piece... NOTICE THE MASSAGE MARKS FROM DREMEL GRINDING WHEEL TO MAKE A SCREWDRIVER SLOT TO REMOVE 3 steel TAMPER PROOF SCREWS & CUT OFF THE RIVET END OF 2 brass CENTER SCREWS...

[camoit]

testing. No such attachments. They did not load for some reason. Make another post and go on. Just ignore it.

[xboxrox]

----------- (1985 Mikuni PicknPull J/Y) ------------ ---------- (Original 1986 Mikuni) -----------



Which one do ya think had the bad secondary throttle actuator..? Why ya think so..?

[geezer101]

Hmm. Good question. A badly fouled secondary throttle butterfly and a sketchy looking primary on contestant #2 HINT HINT

[xboxrox]

Hmm. Good question. A badly fouled secondary throttle butterfly and a sketchy looking primary on contestant #2 HINT HINT

THAT'S CORRECT the 1986 carby gave the truck much less power than contestant # 1

[xboxrox]

PROGRESS ~ Remove Carburetor: (finally working on doing it ~ towards it...)
1) Disconnect battery, done neg side anyway
2) Drain coolant, done one gallon, should be enough to lower coolant level below the intake manifold PHOTOS BELOW
3) Remove air cleaner, pending
4) Disconnect throttle cable, pending
5) etc... pending

My original Mikuni is in my apartment looking like a 500 piece puzzle ~ a PicknPull Mikuni is on the truck (but not for a lot longer)

COOLANT DRAIN PHOTOS

[xboxrox]

Moh Progress

Began testing the carburetor selenoids in my apt; one test is complete & the selenoid operates good, not sure if it will operate correctly in the truck... I will check if voltage is sent to the selenoids when the ignition key is turned to "ON" by probing the carburetor main harness connector pins with a DMM... Maybe the selenoids only receive power when the truck is running & receiving commands from the ECM 'n TPS..? Not sure if the FSM explains testing the selenoids on the truck or not; too lazy to read today...

The Gen1 Mikuni carburetor has a throttle opener/dash pot with a large diaphragm attached to a rod that operates the throttle to prevent it's opening 'n closing too quickly... I searched to locate a source for buying another one but this part does not seem to be available... It would be great to find a seller with this part... All other parts with rubber diaphragms are available on ebay & parts stores but quantities won't last forever...

Aloha & Stay Safe --

[xboxrox]

Did some carby selenoid cleaning this morning, why is there a tiny little hole in the BVV selenoid guys..? Possibly to allow air to move into that little chamber as the diaphragm is pulled back by the selenoid (magnetic pull)..? FYI, only by cleaning did I discover there was a hole & it was plugged solid with hard brown crud... I'm sure if the rebuild carby works that my truck will go much faster now that it has another hole..!


Keeping Safe & Sane --
Aloha George

[xboxrox]

Got new spark plugs installed tonight in preps for a rebuilt carburetor (not yanking the old carb until the hose pinch set arrives)... Next trip to the garage will check spark plug wire continuity & install a new dist cap & rotor... Not being able to work on the truck except for a small block of time at night in clandestine mode + my slow motion is making this dry docking a six month project..! But, it will be worth the expense, time & effort IF the little truck runs even average afterwards... Now, I more fully appreciate having all the knowledge 'n parts 'n tools or a new rebuilt part on hand before tearing into something like a carburetor... Good thing we can survive without wheels if need be...

So, I been researching "Timing Lights" for a way to check the timing on this truck; some lights innova have a tachometer built in... Some lights use D size batteries not the vehicle battery to power themselves (good for jobs like a boat or other vehicle with difficult access to the battery...)

So, I guess a timing light will help check the timing..? Which light do you fellahs recommend..?

The old spark plugs fouled pretty bad huh..? No start..!

[85Ram50]

I have the Harbor Freight timing light. Don't get it. It works but the light is so dim it is difficult to see unless I set up optimum circumstances and have it so close I almost can't see around it. Not one of their better products.

[xboxrox]

I have the Harbor Freight timing light. Don't get it. It works but the light is so dim it is difficult to see unless I set up optimum circumstances and have it so close I almost can't see around it. Not one of their better products.

You just saved me $29.99 plus shipping: THANK YOU 85Ram50
The ESI 130 self powered timing light [Made-in-USA] & [available in places other than Amazon] gets ok reviews, dunno if it has the adjustable timing feature... <--- that feature I assume moves the timing mark around the pully & you then just move the dist to center the mark on the pointer..? No more need to see timing marks on the crank pully balancer to set total timing advance, etc... I also don't think the ESI 130 light has a tachometer to see RPM... Hand held RPM tachometers are another $15-30 @ Summit Racing and I would get one if my timing light had no RPM feature... Thats my thinking right now... A long long time ago, I owned a beautiful chrome metal Craftsman timing light which is vintage now & probably pricey to buy... No complaints on the Craftsman light brightness but those cables & connections to the battery & inductance connector 'n cable were somewhat cumbersome... I also like the top end innova Pro timing light BUT my innova 3320 DMM is not that great, the battery checker lights don't work & I don't think the audable sound works as well + I already have a lot of stuff [Made-in-China] THANK YOU CHINA for everything

Best-O-Luck on your transmission dust cap fix don't use too big a hammer & have a solid hand backup or bench edge to pound on... Check out YouTube vids how to HAND form sheet metal caps cups rounds forms and the like...

[geezer101]

The image is kinda grimy due to the carbon build up, but the plug gaps look massive (to me anyway...) I would regap the plugs to 0.85mm and be a touch more aggressive with the timing. What plugs are you using George? Stick to NGK's or Bosch

[85Ram50]

Thanks George. Let me know what light you get and how it works. I may follow suit.

[xboxrox]

Installed new NAPA dist cap, rotor & plug wires this evening. I hope the mechanic (Sam) gapped the ignition module correctly? The new spark plugs NGK5ES (original spec) gap about .042" am waiting for the hose pinch set to remove the J/Y carb... Can't tell if ESI 130 timing light is Made in US or China -- seen it listed both ways, it's the one I will probably get about $75 & might get a cheapo laser tach... I hate buying tools... Fired up the iwatani butane torch today, should have enuff power to fry or break sumthin

[xboxrox]

Made some progress on the Mikuni rebuild this morning, delay, delay... The nuclear navy taught me that "STOP IS GOOD PROGRESS" [it's better than guessing] and it just came into play... I tried using a 12mm combo wrench to remove the carb's fuel inlet nipple because I thought like all the other threaded fittings, it's O ring would need replacing... Perhaps not..!?! Maybe it does not have an O ring ~ maybe it's a pipe thread connection..? So, I made a command decision to STOP [stop guessing & get some real answers from my friends here at MightyRam50...] The real reason I stopped was because it will require a great deal of torque force to remove that fitting; more than my one old hand X 3" wrench length could muster... an I don't wanna break anything + I don't have a vice, yada, yada...

WHY CANCEL THIS STEP in the rebuild (?)
1) The nipple is on there very tight (might break sumpin removing it)
2) The nipple never leaked (before ultrasonic cleaning in boiling water) and later on the truck, there is easy access & the carb is held solidly
3) If it ain't broke don't fix it (same goes for choke, wax pellet, throttle butterfly blades & throttle shafts...)
4) STOP guessing & get real answers before proceeding
5) A good Nuke is always able to stop a job one way or another much like the P.O. or eBay

[geezer101]

I'd leave the fuel inlet alone unless the carb was sketchy on where you got it from. They are held on with threadlocker and will come off easy enough once the loctite stuff has released. I replaced one with an oversized ID fuel barb on a trick carb I built centuries ago

[geezer101]

...and my offer to send you a kit still stands. Not sure if the MS500B kit is correct for this model Mikuni.
And not sure if you'd get the kit if it went through KENTUCKY anyway

[xboxrox]

KENTUCKY

[xboxrox]

Reassembly Photos

[xboxrox]

REASSEMBLY PHOTOS II

LESSONS LEARNED SINCE LAST POST: <---- NOT GOOD FOR CARB REBUILDING..!

1) BICYCLE SHOPS CARRY SMALL INDIVIDUAL STEEL BALL BEARINGS (LOST THE EGR BALL BEARING ~ MY LOCAL BIKE SHOP HAD THE 1/8" BALL NO ONE ELSE HAD EM THAT SMALL)

2) EXFOLIATION HAPPENS TO METALS WASHED IN WATER SOLUTIONS

3) LUBRICANTS ARE NEEDED TO REMEDY THE EFFECTS OF EXFOLIATION

[xboxrox]

My original 1986 Mikuni 32-35 DID TF has the accelerator pump still attached -- it is a California emissions feedback carb with O2 sensor... Not sure what version the other Mikuni but hoping the 1985 carby on the truck has a matching phenolic body -- do you see any differences in these two carb bodies? Will try uploading a cell phone photo:

The 1985 carburetor arrived & does have the same phenolic throttle body as my 1986 Mikuni

[xboxrox]

Uploading a photo from cell phone (previous post) resulted in a link to the photo but not a ready to see photo... Here are the photos resized with MSFT Paint & uploaded with a laptop PC:



As a result of the differences in the photos above; the Mikuni rebuild project will require removing the carby on the truck & seeing if it has a matching phenolic fuel bowl/throttle body/center section... Awaiting a set of hose pinch clamps from Harbor Freight to arrive before removing the J/Y flooding prone carb... The truck has new ignition module (in the distributor) new dist cap, new dist rotor, new spark plug wires, new coil, new spark plugs... Ignition module gap not checked by me, a local shop did that install, hope they gapped it correctly..? Ignition timing never checked by me, a local mechanic friend (Vernon) did it by ear... If the truck runs again, I may purchase a timing light & Tachometer...

Pandemic is not boring me to death ~ it's the Mikuni killing me ~ can't even get out of the apt to go for a ride ~ my truck is my only vehicle... FORD found on the road dead ~ DODGE dear old dad's garage experiment

More funny DODGE: http://acronymsandslang.com/DODGE-meaning.html

ALOHA --

[camoit]

I see a lot of extra drill holes. I would put on an early first gen all metal one and try it. 90% of the smog tech's don't know anything about carbs.
Never mind you have feedback. Your stuck with the BS.

[geezer101]

The non Cali carb doesn't have the fuel shut off gallery next to the accelerator pump/fuel bowl. A lot of the air galleries appear to be smaller diameter too but that may only be as a result of the picture angle. The early resin body carbs didn't have a lot of air gallery control solenoids (only one IIRC) so the extra galleries are probably feeds to those air circuits.

[xboxrox]

Thanks for that feedback camoit & geezer ~ you must know I love all feedback including Mitsubishi's & Mikuni's & California's... Thank you member 4cylinders for sending me that carburetor simply for the price of shipping... There is a 4 digit letter/number in white letters on my 86 Calif phenolic body but only one white digit is partially visible on the unk # donated phenolic body... There is a big Wasp drinking from my window A/C out on the lanai where both those phenolic bodies are stored... Otherwise, I would run out there right now with a magnifier and check the #s again... No need really, even with the gasket in place, I can see several differences as you guys mentioned... This is a good learning experience for me & hopefully other feedback lovers :^) Last time I checked, Shamrock Wrecking yard in Ridgecrest, CA had three used Calif Mikuni carbs...

As time goes by, I understand more clearly how given the need for a complete rebuild on an OEM Mikuni or installing a new Weber compares... I think a main benefit of the Weber is simplicity and Parts ARE more readily available... Now if there was a similar fix for my leaking steering gear box that a seal replacement did'nt fix, I would like to know about it (does Weber make new steering gear boxes too..?)

Life is Good ~ MightyRam50 & Mr. Mikuni Help Prevent Pandemic Boredom
Aloha --
P.S. When will those dang hose pinch clamps get here..?
P.P.S. I have made contact with a parts puller guy in Tacoma, WA ~ PicknPull yard there has a 1986 4X4 Dodge Power Ram50 ~ if our Rammy truck lives again after it's heart transplant I already have permission for him to pull, ship to rebuilders the steering gear box from that J/Y truck...