Matt Tries – 1984 VF500F Overhaul

Discussion in '1st & 2nd Generation 1983-1989' started by Colddevil, Feb 14, 2020.

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  1. straycat

    straycat Member

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    No Worries Squirrelman. Thanks.
     
  2. Colddevil

    Colddevil Member

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    Wait wait wait. There was good advice in there! I'm here to hear the experiences of people that know these bikes a hell of a lot better than I do.

    Luckily I think I remembered some of it when disassembling and pulling the choke piston(plunger?) lifter arms. And I can see the argument to removing the butterflies if you wanted to pull the valve arm out to clean that throttle shaft bore; however, I left them on before they took a bath.

    ___

    Alright, I decided to take the plunge and disassemble the carburetors and break them apart. I was absolutely befuddled on how to reassemble them last night comparing them to pictures I'd taken. But today is a new day, I've got a clear head, I've been looking at the pictures on my desktop instead of my phone, and I've got some video footage to watch from my disassembly because I knew I'd get stumped.

    Questions/Observations:
    • Question1: It appears that I'm missing most of the dowel pins (have 2 of 8) that align the carburetor intake to the plenum. Are these a necessity to replace prior to reinstalling the carburetor assembly to the plenum? Or are they more for initial alignment and the 8 plenum bolts will hold it just fine?
    • Observation: This carburetor has been re-jetted to 104 mains all around. The bike has a Vance and Hines exhaust, so probably done then.
    • Question2: I couldn't find markings on the emulsion tubes to differentiate them, so I couldn't tell if they were replaced along with the jets or not. Is there a way to tell a difference? I did my best to keep all carburetor parts segregated, but now I'm second guessing myself.
    • Question3: The diaphragm had previously been locked in by some kind gasket sealer(?) that was still soft and easily scraped off. My experience has been this is unnecessary if the mating surface is cleaned up well and the cover is installed correctly, so I didn't use any. Should I go back and use anything to lock it in? If so, what? I tested by blowing into the port, and the slides seemed to operate fine.
    • Observation: This is by far the most confused I've ever gotten trying to do maintenance on a carburetor. And you all weren't kidding when you said organization was going to be pivotal.
    Looking at this picture I took, it actually appears like two of the emulsion tubes are long than the others. Are the longer (if it's not an optical illusion) emulsion tubes for the front or rears?
    2020-03-14 18.28.15.jpg

    I've got plenty of images to go back through, so I'm confident I'll get the fuel pipe, vent pipe, and choke linkage figured out. Just going to take my brain a while to digest.
    2020-03-14 16.42.12.jpg

    We'll see if I'm able to find some time today to give it another shot. Unfortunately, the ole Coronavirus is forcing me to get some work done this Sunday due to needing to get more people setup to work remotely. What a crazy thing going on in the world now.
    2020-03-15 09.43.56.jpg
     
  3. Colddevil

    Colddevil Member

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    Actually, I think I'm running into the exact same question that user Invisible Cities had in a post from 2009. https://vfrworld.com/threads/vf500f...ow-jets-emulsion-tubes-and-jet-needles.32795/

    That is, the emulsion tubes on cylinders 2 and 3 appear to be the same, and cylinders 1 and 4 seem to be the same. However, this would mean that the fronts (cyl 2 and 4) would be mismatched, and the rears (1 and 3) would also be mismatched. This is what I've observed and why my shorter-looking emulsion tubes look like they're on 2 and 3 in what he called "criss-cross".

    It's hard to make the pictures out since Photobucket has em blurred; however, there's enough there that I think I can say it matches my setup. Blurry screenshot from that thread:
    1.JPG

    In my head it makes way more sense that 2/4 and 1/3 would be paired instead of 1/4 and 2/3 like I'm seeing.
     
  4. Diving Pete

    Diving Pete Member

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    Front / rear is the normal pairing. But don’t know for this model... although would put a beer on it.
     
  5. squirrelman

    squirrelman Member

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    tubes should match, fronts the same/rears different from fronts but matching each other. if not right, carbs could have been incorrectly assembled before. tubes are either high holes or low holes.

    u can't consider any slow jet is clear until u can pass a .010" steel wire through easily; just seeing a bit of light doesn't mean the jet is clear.
     
    Last edited by a moderator: Mar 15, 2020
  6. straycat

    straycat Member

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  7. Colddevil

    Colddevil Member

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    My money would be on winning that beer with the same pairing. I just want to be diligent before buttoning it back up and because I seemingly ran into the same conundrum as that poster did a decade ago. I think we'll win this beer though.

    "Tubes are either high or low holes". <--You wouldn't happen to know which go where, do you? This is the first time I've heard this stated, and it only just made sense to me after pulling the emulsion tubes back out. Do you know if the taper is the same? I managed to find an Excel sheet of basically every Mikuni needle/needle jet spec, but I can't find an equivalent Keihin sheet.

    In regards to the steel wire, I don't have any of that on hand. But I did buy some fishing line a few years ago that I keep specifically for carb cleaning. I had to pull it out for one of the mains on this cleaning. Luckily I was able to bust through with the relatively weak fishing line. I'm told that a guitar string would be good to have on hand though. Or is there a better tool to have on hand?

    Will 100% be checking some of these out to see how he lines up the fuel/vent lines and carburetors. Thank you for the recommendation!

    __________________________________

    Alright, so I decided I couldn't go to sleep without double checking what my needle/needle jet situation was. Turns out I've partially validated what I've been told by everyone here (fronts and rears are paired), and I've discovered more evidence that I'm going to be deviating a bit from the manual.

    The apparent difference in size of the emulsion tubes was an optical illusion in the picture I posted previously. Unfortunately, there are no markings on the emulsion tubes with a part number. But I do now understand what Squirrelman meant by high holes or low holes. My #1 and #3 emulsion tubes and #2 and #4 are paired. The only difference I can perceived (because inner taper would be impossible for me to check) is that the rear carburetors have one of three holes about 1-2mm lower than the 2/4 fronts.

    Speaking of differences in the needles... well. It turns out I don't have stock needles. I felt I needed to pull them out and document which part number was printed on them since those are actually spoken of in the manual. Turns out, I've got aftermarket needles because these have circlip needle height adjustability and no part numbers stamped on them. My understanding is stock would have stamped numbers and need to be adjusted with shims.

    Anyway, I guess I can put this issue to rest until I get to the point of firing up the bike since no Honda manual is going to be able to tell me how to deal with aftermarket needles and aftermarket (#104 all around) jets. The bike ran perfectly well for the meager 8k miles I've put on it, so I guess I'll stick with it. The only modification I'm making is setting the A/F mixture screws to 2 turns out instead of the 2.5 they were at because that's what the manual calls for.

    2020-03-15 21.00.43.jpg
     
    Last edited: Mar 15, 2020
  8. squirrelman

    squirrelman Member

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    see if you can find an ultrasonic cleaner for the brass parts as they need improvement. or boil them in a solution of vinegar and water.
     
  9. Colddevil

    Colddevil Member

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    They just came out of one yesterday. They look awful in that picture, but scroll up a few posts and look at them while they're sitting inside the diaphragm covers right out of the ultrasonic--they look like different emulsion tubes altogether.

    I'm not trying to be dismissive of the advice because it also struck me how they turned out looking in that picture. But I've had each of those thru the ultrasonic for 20 mins, carb cleaner spray, fishing line, and compressed air.

    I also thought the picture might illustrate the "high holes or low holes" to somebody that might run across this in the future.
     
  10. Colddevil

    Colddevil Member

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    After pondering over the orientation for reassembly for a week, I finally had a breakthrough after watching the videos Straycat linked me to, and I got it reassembled. Unfortunately, those videos (nor any other I can find) show the technique for how to fit the carburetors back together and securely push the fuel/vent tubes into place. They're super tight fit with new o-rings, and you can't really rotate them in. I was most worried about the "zee" fuel pipe. The "ess" fuel pipes I felt like I had positively inserted the whole way in.

    Reassembling the linkage wasn't that difficult once I wrapped my head around it. Just time consuming and tricky--especially the washers on the choke linkages. What surprised me was just how easy it was to line up on the airbox plenum! It fit right on and I didn't even have to squeeze anything to get the bolts through to fasten it down. Only one spring under the sync screw was a bit tricky.

    2020-03-20 22.42.11.jpg

    Unfortunately... I'll be disassembling it all again. I hooked it up to an auxiliary tank to verify that it held fuel. And it started pissing from the center. Had a meltdown last night and just wanted to be done with it. I think that's part of the process.

    Went down again this morning to more slowly drip fuel into it to try to pinpoint the leak. It's from the "zee" fuel pipe. I was worried about the ends mating flush because it looks slightly twisted (though my disassembly pictures show the same slight twist); however, I believe it's actually dripping from the center of the damn thing. Which means I either don't have it fully pushed together (the "zee" pipe is two pieces), or I forgot to reinstall the o-ring in there completely. I'm hoping that's the case, anyway.

    2020-03-21 08.42.17.jpg

    2020-03-21 08.44.54.jpg

    No matter what I tried, I couldn't get the "zee" to sit more straight. This picture exacerbates it a bit, but it also might mean that the zee isn't fully pushed together which might cause the twist. The carburetors simply can't be pushed together any closer to squish it in because everything else on the linkage and mating to the plenum lined up perfectly.

    Edit--found a picture of the "zee" pipe during disassembly and the o-ring I'm worried about.
    z.JPG

    Guess I'm putting off Doom:Eternal for a while longer because I don't want this looming over my head.
     
    Last edited: Mar 21, 2020
  11. NorcalBoy

    NorcalBoy Member

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    You'll get it, but I completely understand the frustration. Once you get it, you'll have that knowledge and experience in your tool box for the rest of your life, and you won't have $50,000 of student loans to pay back :Heh:

    I recommend using a little Krytox, or Super Lube 93003, silicon o-ring grease on the o-rings before slipping everything back together. Just a light coating will help things slide together nice and smooth and help to make sure the o-rings don't get rolled, or knicked. It also conditions the o-rings and keeps them nice and soft. Works great on intake boots as well. You're almost there!
     
  12. Colddevil

    Colddevil Member

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    So it was definitely the z-pipe not being pushed in completely to join the two halves. I was able to pull two of the carburetors off, push it together, and reassemble without issue. So that was great news. You can see it's much more straight and flush with only a tiny bit of twist in it now. Thanks again for the suggestions on here and in chat. I skipped the oring coating because, unfortunately, didn't have any light silicon grease on hand. Stuck with the marvel mystery oil. 2020-03-21 11.32.08.jpg

    The next conundrum I'm having is how painstakingly slow the carburetors filled with fuel when hooked up to the aux tank. Where it previously just flooded through (and out the z-pipe), it took me probably 20 minutes of tapping on the fuel line and rotating the carburetor assembly around to work fuel into all the bowls. I'm not sure it ever would have gotten to carburetor 4 if I hadn't rotated it.

    So I'm wondering, is this a potential venting issue? Or might I just have the floats set too conservatively since I did replace with new float valves and float valve seats. The manual calls for 6.2mm, and I got them all set to roughly 6.3-6.4 and checked with both a caliper and gauge. Out of the box they were around 8mm--likely because the springs in the float valves hadn't completely worn out like the ones they replaced.

    I know that the fuel pump would likely provide more fluid pressure and likely fill the bowls quicker, but this still seems a bit alarming. When I did a similar test on my Bandit, the bowls fill immediately until the floats rise and seal. This almost seems to me like the floats aren't even open.

    Do I need to get back in there and raise the floats? Or is this normal behavior for this carburetor, and the fuel pump will fill the bowls no problem? I'll do some more research, but I want to figure this out before fitting it back onto the bike.

    2020-03-21 12.42.55.jpg
     
    Last edited: Mar 21, 2020
  13. Captain 80s

    Captain 80s Member

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    When adjusting float levels, you have to check with carbs rotated to just when the float contacts the valve, or you will get incorrect readings. If you are adjusting/checking them with the rack upside down on the bench, they will likely not be correct due to the weight slightly compressing the spring loaded button.

    And if you have an aux tank high enough above the carbs, they should fill pretty damn fast.
     
  14. NorcalBoy

    NorcalBoy Member

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    I'm sure everybody has their own methods. I used an old hotel room card and cut my own gauge, that way I knew the measurement was exactly what I wanted, and that the gauge would fit perfectly over the floats. The floats on my RVF carbs were not the same shape on both sides. I started by using a piece of glass to ensure that the bottoms of the floats were exactly parallel, prior to installing them.

    Once the floats were confirmed to be parallel, I set the floats before I assembled the carbs. My method was to hold each carb at roughly a 75-80* angle in one hand, with the float tang completely off of the valve tip, ensuring the valve was completely seated, and then slowly rotating the carb back, so that I could get a really good look at exactly when the float tang contacted the valve tip, taking extra care to make sure the valve was completely seated before I started measuring. Once each float was set, I performed the same operation multiple times to confirm the measurement. It was a tedious process, prolly took 15 minutes a carb to get them set as close to perfect as I could. Only then did I assemble the carbs as a set.

    Once assembled, I used a piece of guitar "E" string to bench synch the throttle plates, before installing them on the bike.
     
    Last edited: Mar 21, 2020
  15. Colddevil

    Colddevil Member

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    I'm glad you said this because it made me second guess if my angle was correct. I didn't think the spring was depressing with the angle I had it propped up at; however, I was about 0.7-0.9mm high on all of them. Measuring at justtttt the point it contacts, I'm as close to 6.2mm as I could get. Thank you.

    I like to use the ruler first just to know I'm in the area, but then I use a digital caliper. I'm thinking gauge like you made would probably work more consistently, but I try to measure several times after totally resetting to know I'm not misreading it. The VF500 84' carbs also have dissimilar float shapes. If there's a way to remove all 4 carb bowls without removing from the plenum... I'd love to know the trick. I can only get 3.

    I used a fishing line to bench sync. I need a guitar string.

    __________________

    So you ever wonder if someone out there is just trying to make your day more difficult? After readjusting the floats, I set the aux tank back up to try again. This time when I turned the valve, nothing. What the hell? So I took the float bowl off of #1 to watch while it was hooked up... nothing. So I took the aux tank off completely and opened the valve. Nothing. The goddamn rubber piece inside of it spun and stuck in a spot that nothing was going to come through. :Frusty:

    2020-03-21 16.22.07.jpg

    Buttt I remembered I had another valve I bought to hit a free shipping number at 4into1 I believe. Hooked that bad boy up, and!...

    Pissing out the z-pipe. Probably disturbed it when I took the plenum off again to measure the float heights because I couldn't get either carb 2 or 3 float bowl off. Ugh. So, back to the exact problem I started with this morning. I suppose it was worth it to recheck the float heights and figure out the valve issue. Gonna give the z-pipe one more go today.
     
    Last edited: Mar 21, 2020
  16. NorcalBoy

    NorcalBoy Member

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    Noooooooooo! Fawk, man, I'm so bummed for you right now. I am sending my best mojo your way, I really want to see you get this nailed today. I believe you deserve a win, at this point. You earned it.
     
  17. Colddevil

    Colddevil Member

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    All is not lost for the day! Broke 1 and 2 off again, cleaned the inner surface of the female z, and I pushed the two z-pieces together hard with marvel mystery as the lubricant. Got the aux tank back on, and it's holding! Going to leave it on the tank while I clean up and then leave it over a clean paper towel for the night w/o the aux and check for leaks.

    If this didn't work, I was ordering some of the gasket grease you mentioned and some various size viton orings. Still probably should since I'm sure I'll need them in the future if Coronamania doesn't make this all immaterial. Thanks to you and 80's again for the advice and encouragement!
     
  18. straycat

    straycat Member

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    Nice work !!
     
  19. NorcalBoy

    NorcalBoy Member

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    Sheer force of will! I hope this is truly the end of your suffering. Waiting for the "wrapped it all up" post.
     
  20. Diving Pete

    Diving Pete Member

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    i use Castro red rubber grease for all orings.. Makes more of a difference than you would think..
    Don't worry about having to pull the carbs again - I had to do one of my RVF's set 3 times as it just wouldn't seal.. Eventually used a Q-Tip in a drill dipped in polish ... Now works perfectly.. lol
     
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