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My XS400 "restore"

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

  1. SoulMan

    SoulMan XS400 Addict

    I just bought an xs400. It needs some work. The carb is not connected as one of the things that slide up and down in the carb would not slide up all the way.

    Before I do a bunch of work I want to do a basic start test. Is this a good place to start with it?


    It is a 1980 but I dont know more than that.... Is this an xs or is it an rs ... the title has rs on it

    Last edited: Jul 4, 2018
  2. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor


    The VIN prefix will give you the info you need, the first 3 digits. It also makes it easier for the forum when help is needed.

    Get a new/good battery and turn the key on. You should be able to check your lights. You need a battery to start the bike and keep it running. The bike will not function without one unless you do some major modifications.

    I would read the manuals first, check fluids and check the valve lash. Check plugs also, this might give you an idea of how the bike was running when it was on the road.

    The carbs are the major thing about these bikes. Rebuilds are almost always a must-do for the new owner and cleaning them is an absolute.

    Hopefully, youll be able to salvage the carbs. Id probably soak them or at least give them a good spray with something. Take the caps off the carbs, the rubber diaphragm part will tear easily and they are about $70 for a pair. If they have holes or tears they are no good.

    Your bikes looks like its in pretty good shape though.
  3. SoulMan

    SoulMan XS400 Addict

    Hey NHM thanks for the response. The vin starts with 3F8 which from this site http://www.johnnystoybox.com/parts_cross.htm says its an XS400G I took the caps off the carb and cleaned the metal part attached to the diaphragm and inside that area of the carb and the metal component slides freely up and down right now just like the other side so it looks like it should be good. I did not notice any tears in either of the diaphragms. I will most likely do a thorough cleaning at some point but for now that is a start. No owners manual as far as I know. But good point on checking fluids and such. I think its been sitting for a couple years so certainly changing the oil would be a good idea. Honestly I didn't even try to kick the kick start to verify it wasnt seized. But I certainly did not get that impression from the PO :( I will have to try next time I can... bike is currently stored at my brother in laws.

    I will definitely need some type of basic way to wire it up. Right now there are lots of things unplugged because the PO was trying to find the short that was blowing the main fuse. So I would want to buy pass the ignition switch and pretty much all other electrical components that I can in order to just try to start it. I am a newbie to motorcycle setup but do have some mechanical inclination and can do electrical in a house so I figure I should be able to wire this up but if anyone has a basic wiring diagram just to get a test done I sure would appreciate being directed to it. I looked for some but I feel like I am not sure if something I read for say a 1982 would work for a 1980.

    I would like to bypass the OEM electrical switch just to rule it out as being part of the short. Just seeing if it can start and bypassing all the current wiring to avoid the short is the main reason I want to do this before I start thinking about really trying to get the bike into a better shape.

    Any guidance that someone could provide would be greatly appreciated. I will keep looking and if anyone has a good source for a service manual that works for this specific model being directed to that would be greatly appreciated. I don't mind buying something if necessary. Thanks!
  4. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    You can find wire diagrams here as well as the manual. I have the Haynes manual myself that is very helpful. The fuse boxes on these bikes are not the best especially when they are this old. They are nice and slim though. Every connection and harness plug on the bike needs to be pretty good, if anything is corroded, especially the fuse box, things will not work. Make sure you can establish a good ground to the engine from the battery, and theres a bunch of grounds on the main wire harness.
  5. Petew

    Petew XS400 True Believer Top Contributor

    The 1980G headlight won't work unless the bike is started. Just a heads up so you don't spend hours chasing a problem that doesn't exist. Learned the hard way....
  6. MrStubb

    MrStubb XS400 Addict

    Looks like the same as my bikes. Both are 80 XS400G's 1 is for parts. Like NHM said Carbs Clean em & learn their quirks. They're not really hard but as I found out the can be temperamental. Those Diafram's are SPENDY and most likely your fuse box is in rough shape like mine were. There's a good replacement at most auto parts stores that use the newer style fuses. I might have a good light bucket for you if need. Good luck!!!
  7. xschris

    xschris a lifestyle not a trend Top Contributor

    If you want a good reliable bike keep the stock exhaust and air boxes. It will make you life way easier. Also you will get the best performance out of it that way.
    jzeron likes this.
  8. SoulMan

    SoulMan XS400 Addict

    Thanks for the responses. I appreciate it.

    NHM - The fuse box is in bad shape for sure. So it will definitely need some attention.

    Petew - Thanks for calling that out. I saw that in another thread as I was researching the electrical.

    MrStubb - Before I knew better I sprayed carb cleaner into where the diaphragm piston slides reside. I took the caps off and the diaphragms look ok. I am hoping I did not damage them or at least they will work well enough for my test to see if this bike will even run.

    xschris - I saw some spots on the exhaust where they are starting to rust through. Any suggestions for that?

    All -
    For a basic start test I found this simplified wiring.
    I found this image on this thread
    wiring 400.png
    To just get enough wiring up for a start test I am trying to figure out how to wire the stuff up and what I can cut out. Obviously I can cut out the tail light headlight and the corresponding switches. Maybe even the starter motor portion of the wiring if I just want to try to kick start it. Although it would probably be easier to try to get it started with the electric starter. I assume all of these components pretty much have some type of stock wiring harness clips which would make it hard to wire the components direct for the test. Is that a valid assumption? If I take out the main switch and the kill switch I assume the coils then would just be wired directly to the 20 amp fuse instead of to the kill switch.

    Something like this:

    Assuming I control the battery negative to frame and the blue starter solenoid to ground wire to frame manually I can at least get a feel for this thing turning over. Sound about right?

    Thanks all!
  9. Petew

    Petew XS400 True Believer Top Contributor

    As far as fuse boxes go you can replace them cheaply with a 4 slot spade style fuse block on eBay for next to nothing. I have used them 2X. If not then just do inline fuses on the individual circuits, easy to hide away.
    You can also pull the plugs and squirt a little oil down into the cylinders and let it sit and possibly loosen and lube things there. If your kick starter doesn't turn it over with minimum effort DO NOT FORCE IT!!! Again a lesson learned when someone thought they could "break loose the seized motor" that was only stuck in gear. Broken journal equals e-start only.
    Last edited: Jul 7, 2018
  10. spectra

    spectra XS400 Junkie Top Contributor

    Remember if stuck in gear it wont roll........Pete didnt try that one :D but otherwise yes some oil in there and let it sit for a while. These little motors are pretty bullet proof and can sit for a long time and still run years later.

    Good luck with it !
    Petew likes this.
  11. Petew

    Petew XS400 True Believer Top Contributor

    It wasn't Pete that did it. It was on its stand and I went to get a battery. Thanks Spectra! Can't let me forget the kick start....ever!
    spectra likes this.
  12. spectra

    spectra XS400 Junkie Top Contributor

    :laugh2: sorry my bad..........I just know Pete and kick starters dont get along ;)
    Petew likes this.
  13. SoulMan

    SoulMan XS400 Addict

    Images of the MC in its current condition:
    20180711_182739.jpg 20180711_182824.jpg 20180711_182746.jpg 20180711_182806.jpg 20180711_182852.jpg 20180711_182910.jpg 20180711_182921.jpg 20180711_182936.jpg 20180711_182941.jpg 20180711_182947.jpg 20180711_182954.jpg 20180711_183009.jpg 20180711_183044.jpg 20180711_183424.jpg 20180711_183526.jpg 20180711_183534.jpg

    Attached Files:

  14. SoulMan

    SoulMan XS400 Addict

    20180711_183719.jpg 20180711_183838.jpg 20180711_183933.jpg 20180711_183954.jpg 20180711_184015.jpg 20180711_184046.jpg 20180711_185845.jpg 20180711_184133.jpg 20180711_184214.jpg 20180711_184255.jpg 20180711_184303.jpg 20180711_184423.jpg

    Attached Files:

  15. SoulMan

    SoulMan XS400 Addict

    So this thing has a short somewhere but I would like to just see if I can get it started. I am looking for a recommended list of things to do before attempting to start it.
    1. Pull the plugs and put a little bit of oil in the cylinders.
    2. My brother in law has a motorcycle battery I can use to try to get it started not sure if they are the right size. If it doesnt work will just bite the bullet and buy one.
    3. Change the oil and filter. I don't know when it was last changed so this makes sense before trying to start it. Do I need to do something about the oil leak? I just saw how much oil was on the engine in the picture above. I don't mind changing it later and figured I probably would do that anyways (any input about where that oil might be coming from and how to fix it would be greatly appreciated)
    4. NewHavenMike mentioned earlier checking valve lash. Looks like instructions for doing that are here: http://www.xs400.com/threads/a-bunch-of-how-tos-in-a-thread.10715/#post-119439
    5. Compression test? Anyone have a good recommendation for a compression tester that wont break the bank and let me get what I need to feel comfortable here about the condition of the engine?
    6. Figure out how to wire up the electrical for a general start test of the bike. If anyone has a down and dirty thread out there that will get this done I would really appreciate it. I have yet to find something I feel really comfortable with. My engineering brother in law said I would probably need some type of kill switch as once the bike is running unplugging the ground on the battery wouldn't stop it. This makes sense to me. I assume the coils would be providing the electricity to keep the bike running and that unplugging the battery might have a negative impact to some component in the long term.
    I found this thread: http://www.xs400.com/threads/how-to-what-to-do-first-with-your-new-xs400.10595/

    Which seems like a good start for overall things to do before riding it but I am not trying to make it ride ready right now. Simply trying to see if this motor is going to be good or not before I spend a bunch of time working on the bike to get it cleaned up.


  16. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    You can use a car battery to start the bike if you have to. Youll just need to use a pair of jumper cables and connect them to the battery wires on the bike. Then youll have to keep the car battery connected of course while it runs. Just don't crank the starter endlessly. Only crank it for a few seconds at a time and give it a rest after a couple tries.

    You can change the oil and filter and clean the trap, I think I would just top the oil off if youre only trying to start it for a few minutes. Give it a couple kicks to prime the oil pump and take the valve caps off and dump some oil on the lifters and cam. You can spray fogging oil in the cylinders, this will give you better coverage, then add some gas in the cylinders after you kick it over once or twice. Put the spark plugs back in and hear it start
  17. SoulMan

    SoulMan XS400 Addict

    Good idea... now if I can only figure out how to get it all back together so I can give her a go. I know there is a short somewhere but I suppose I can just replace the main fuse and hope that it lasts long enough to just to get a feel of how it will run. Assuming it does start did you have any recommendation on a compression set to determine the current state of the motor that wont break the bank.

    This makes sense to me. If I am not riding it probably is sufficient for a start test.
  18. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    I think I picked up mine from Harbor Freight, maybe Pepboys? I cant remember. Probably cost $30... The kick starter should give you a good idea of compression. If you feel the compression build and then it suddenly releases, you have something. You can always turn the engine over with the starter and plug a spark plug hole with your finger. Just be sure to ground the spark plug whenever you crank it over.

    If you get spark, and timing is good, and you poured gas in the cylinders, it should start right up within one or two kicks. I always kept in mind that if you can get a stable idle going, then youre compression is probably OK for now. For the test start, Id probably kick it rather than use the starter.

    My bike always starts easier with the kicker, I think its because I have a smaller battery and the starter hogs volts and makes it a bit harder to start when its hot.
  19. SoulMan

    SoulMan XS400 Addict

    Thanks. You have been a great help. When I get some free time I will see if I can get this running and I will record a video of that process. :)

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