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My XS400 "restore"

Discussion in 'The Garage' started by SoulMan, Jul 4, 2018.

  1. SoulMan

    SoulMan XS400 Addict

    Another question. I finally purchased a battery for the bike but then I noticed the ring terminal for my negative wire was broken. I am looking to fix it and I am wondering if anyone has a procedure for that. What type of terminal to buy for example or size etc. Just whatever information that I can use to fix it.

    Also check out this video and tell me if is concern about the "wobble" when the starter clutch spins. To me I wonder if the crankshaft is bent. I am a bit concerned that when I took the starter clutch off to get to the springs and replace them that I got a little bit heavy handed with the ratchet to get the starter clutch off and that maybe I bent the crank.

    I want to get a dial indicator and take the starter clutch back off so that I can check to see if the crank is indeed bent or if just might be how the starter clutch went onto the shaft.
  2. xschris

    xschris a lifestyle not a trend Top Contributor

    My guess is that the fly wheel is not on straight. Make sure the shaft key slot is in good shape and the key is there. How much torque do the use for the center bolt. The specs should be in the manual.
    BBS360 likes this.
  3. SoulMan

    SoulMan XS400 Addict

    I believe around 25 or so ft pounds of torque is what the manual says. My torque wrnch goes down to 30 .I need to get a couple that have some different ranges. But its hard to buy the cheap ones and not the nice ones haha .
  4. BBS360

    BBS360 XS400 Guru Top Contributor

    Yeah, if the rotor didn't seat properly on the tapered shaft it would be forced against one of the tapered sides and not the other, producing the wobble even if torqued.
    Need to make sure the woodruff key mates in the grooves on both the shaft and rotor and that the rotor seats all the way down on the taper.

    I don't think you'd be able to bend the crankshaft unless a sledgehammer was used to remove the rotor.
  5. SoulMan

    SoulMan XS400 Addict

    Good to know... right now I am trying to sort the carb fuel issue out but I will certainly check it. Thanks!
  6. SoulMan

    SoulMan XS400 Addict

    Well so far no go on the carb. Pretty sure fuel just isnt flowing because the plug is dry after I tried to turn it over a few times. Doesnt look like I am getting fuel even after setting the float height. Here is where one side looks:


    I set both sides the same way with my caliper. I did not get a chance to check the float height like this with the other side because the float bowl drain plug is stripped.

    Mine looks like this or it would if it didnt look like someone has been chewing on it I suspect:


    But yamahapartshouse part number for the plug seems to be leading me to this:

    2018-10-20 18_09_07-Yamaha 34mm BS34 CV Carburetor Drain Plug Bowl Screw 1A8-14991-00-00 _ eBay.jpg

    So not exactly sure how to find the exact proper plug I need to replace the existing one.
  7. BBS360

    BBS360 XS400 Guru Top Contributor

    Different years used different style drains.
    If yours matches the first one that's the one to buy.
  8. brendonna69

    brendonna69 XS400 Member

    Buy a 6 gang blade style fuse box from summit racing, and swap it in. Mine fit directly into where the old one was. And get a new battery. Check your oil for metal flakes. Etc.
  9. SoulMan

    SoulMan XS400 Addict

    Well... the woodruff key was not in correctly. It had fallen out and was wedged between the starter clutch and the side of the crankshaft surfaces. It was deformed a bit and I could no longer get it back into it's slot. But I hammered the deformation out a bit so that I could properly install it. Now it is perfect.

    Regarding my fuel issue anyone have any suggestions for what I should check while I have the carbs off the bike. I believe I have everything in place and am pretty sure everything is cleaned up real well but since I have it off the bike I might as well be thorough. I assume the only things that need an adjustment are the pilot screw, float height, sync screw between the two carbs (bench sync), and the idle screw which doesnt apply if I am holding the throttle open to try to get the darn thing to start. Other than this I should make sure the jets and passages are clear.

    Any other thoughts?
  10. xschris

    xschris a lifestyle not a trend Top Contributor

    If they are setup and working as they should you should never need to touch the throttle to get it to start. Your enricher circuit or "choke" will do it for you. Post some pics of the carbs apart and together. Maybe we can see something. How is compression?
  11. SoulMan

    SoulMan XS400 Addict

    When I tested compression I was around 150 each side but I havent adjusted valves yet either. Was trying to get the bike running well as it would only run with full enricher and even then not very well. When moving the throttle it would die. I will see about getting pictures of the carbs.

  12. SoulMan

    SoulMan XS400 Addict

    Here is what i have by the way of pictures.

    20181023_200838.jpg 20181023_200816.jpg 20181023_200829.jpg 20181023_200824.jpg 20181023_200820.jpg 20181023_194937.jpg 20181023_194937.jpg 20181023_194845.jpg

    All the jets are clear. Only question are the passages. The diaphragms appeae to be good. If i block the air passage to them they dont want to slide down and I looked at them for any pinholes. I made sure the choke passage in the float bowl was clear.

    See anything besides the broken float post? :(

  13. xschris

    xschris a lifestyle not a trend Top Contributor

    The broken float post will cause issues. You should not have a washer under the pilot jet plug screw. If it is the right kind of screw it will seal on it's own. Did you set float levels with the gasket off the carbs and set both sides of each float? (26mm) On each float bowl there is a hole down each side. This is you pilot circuit pickup. Make sure it is clear by spraying a little carbs clean down it and see if it cones up into the bowl. Post me a pic of the engine side of the carbs that hold the pilot mix screws. I would like to see if they look damaged or have been drilled at any time.
  14. SoulMan

    SoulMan XS400 Addict

    I just took the gaskets off and verified the float heights on both sides of each float. I did ajust the height and leveling of the floatsvery slightly. The parts diagram for the 79 carb on yamahapartshouse does show a washer on the pilot jet plug screw.

    Here are pics of the engine side of both bodies. They dont look drilled out to me but ive never seen another carb like these.

    20181024_070512.jpg 20181024_070351.jpg
    I did verify that the enricher circuit flows from the edge of the bowl into the inside of the bowl. I actually took a guitar string to the curcuit last night to be sure it was clean. I also sprayed carb cleaner into the pickup tube at the bowl area and verified that it flows up into the port that gets open at the engine side when you pull the enricher.

    Thanks for checking it out Chris!
    Last edited: Oct 24, 2018
  15. xschris

    xschris a lifestyle not a trend Top Contributor

    . Looks like the butterfly valve screw look like someone has tried to remove them. Make sure they are tight and the plates fit/close flush. There should be a 135 stamped into them facing the motor.
    Last edited: Oct 24, 2018
  16. SoulMan

    SoulMan XS400 Addict

    Yes I did that to the butterfly valve screw :( I took them out before I learned that they were punched in the back. I figure I am going to put some red loctite on them. I just checked the plates they are tight and fit I think as close and flush as they can. They do have 135 stamped on them and facing the motor.

    The hole for the mix screw is completely clear. I put a light inside that area there and looked in from the top and they are wide open.
    Last edited: Oct 24, 2018
  17. xschris

    xschris a lifestyle not a trend Top Contributor

    The 77 and 78 carbs don't use the washer for that plug. I don't think my 79 has it either. Hard to know what exact year carbs you have as the 77-79 all look alike. If you have the correct factory screw you should not need the washer. I am just trying to eliminate anything that could cause issue.
  18. SoulMan

    SoulMan XS400 Addict

  19. xschris

    xschris a lifestyle not a trend Top Contributor

    With a broken float post that carb will never work as it should. Even a few mm of movement will cause issues.

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