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Question about replacing batteries

Discussion in 'The Garage' started by Jamps, Sep 14, 2020.

  1. Jamps

    Jamps XS400 Member

    Hey everyone,

    I'm super new to this forum and super new to the XS400.

    I recently picked up a 1979 XS400F and the battery is real old, and real dead. I really want to replace it with a maintenance free battery but I can't seem to find one that says it works for the 1979 model.

    BikeBandit says the Bike Master AGM Platinum II fits the 79 model, but other sites say its only for a 1980-81 even though it says it is a replacement for the 12N12A-4A-1, which is what this 79 had already. Is there really a big difference? If anyone could tell me if this battery would work, or point me in the direction of one that does I'd be really grateful, I wanna ride this thing!

    Bike Master AGM Platinum II link for reference - https://4into1.com/bikemaster-agm-platinum-ii-battery-ms12-12a-4a1/

  2. amc49

    amc49 XS400 Addict

    If you have already fitted that exact battery in place the new one should work too. Application lists are often woefully incorrect.
  3. Jamps

    Jamps XS400 Member

    thanks for the reply. I spoke with Bike Master this morning and they told me that all the XS400 bikes used the same battery, which I'm sure is common knowledge around here. So they said I could use the AGM or True gel 12N12A-4A-1 replacements instead of the conventional battery. [I got the AGM.]

    After I get the battery in, it's time to kick! This is my first kick start bike, and I'm excited to exhaust myself trying to start it.

    Thanks again!
  4. xschris

    xschris a lifestyle not a trend Top Contributor

    The F 79 should have a e-start also. The 79 2-F is a kick only. Post some pics of the bike.
  5. Jamps

    Jamps XS400 Member

    Yes you're right, It does have an electric start but it wasn't functioning when I bought it. I just get a click when I press the button. I'm hoping that was just cuz the battery was crummy, otherwise I have no idea. The Starter motor, maybe?

    I'll take some pics when I go put the new battery in for sure.

  6. xschris

    xschris a lifestyle not a trend Top Contributor

    My guess it was the battery.
    Jamps likes this.
  7. amc49

    amc49 XS400 Addict

    Could be something as simple as a starter solenoid too. With a bit of effort you can often adapt say a $20 rider lawn mower solenoid to take the place of a super expensive exact replacement factory part. Been running one for years on my CB550F, the quickest $60 I ever made out of thin air.
  8. xschris

    xschris a lifestyle not a trend Top Contributor

    Lots of stock oem ones can still be had for cheap. Yamaha used them in a bunch of bikes. I have a bunch of them. Just plug and play.
  9. amc49

    amc49 XS400 Addict

    Lucky y'all then, commonly they go for $80 on the big Hondas. Ridiculous. Part of it being the timidity of people to think OEM is the only thing that will work. When you can run 2 inches of wire to save $20 I go for it, none of my stuff is 100% OEM but it doesn't break either. I do the same with the cars to save $$$$ megabucks too.
  10. Jamps

    Jamps XS400 Member

    Thanks for the advice everyone.

    Is there any kick starting advice you have for me?

    A technique, or the steps I should take, or things i should never do?

    I really am only used to electric start bikes.
  11. amc49

    amc49 XS400 Addict

    Make sure you are in neutral, kill switch is off (on), gas turned on and use the choke if cold. If engine is in tune and good shape it should start on first kick. It's small enough you shouldn't have to move engine to get on a compression stroke, they don't kick back like a big single will.
    Last edited: Sep 16, 2020
  12. Jamps

    Jamps XS400 Member

    I know that the previous owner had to kick it many times before it would start-up. My assumption was that when I bought it the carbs probably need a good cleaning.
  13. amc49

    amc49 XS400 Addict

    Could be other things like timing too. if points then they need to be kept pretty sharply on spec. Out of a hundred bikes I've had only two show any starting issues, one had water ingress into the magneto and it simply would not kickstart, you had to pushstart it and forever until it lit off. Cleaning the mag rust off and points up to reset them had it then kicking easily to start with only a half kick. I was just young enough I didn't know about such things and Dad showed me what to do. The other bike was simply dead worn out, the rings were broken in several places and why. Both once running would run forever, they just wouldn't start reliably.
  14. Jamps

    Jamps XS400 Member

    My service manual comes in the mail today, so that should hopefully help me with troubleshooting that stuff.

    I'll let ya know how it goes as it goes,

  15. Jamps

    Jamps XS400 Member

    So, I put the new battery in and the starter functions again! Huzzah!

    However, after hitting the electric starter a few times and after what felt like 40 kicks I couldn't get this engine going.
    There were a few kicks where it started for a second but it gave up quickly, and then eventually so did I.

    Gunna look at the spark plugs next, and then I guess the carbs.

    Here's a pic of it too.

    Attached Files:

    BBS360 likes this.
  16. Jamps

    Jamps XS400 Member


    Got the bike running using the electric starter yesterday! And then after it was warmed up the kick starter would also work, by 2nd or 3rd kick it was good.

    Funny thing though, the choke had to be pushed in all the way or else it wouldn't start at all, and this is a cold start after it sitting in the garage a few days. And if I pulled it out during warm up it would die.

    Anyone have a similar issue like this?
  17. amc49

    amc49 XS400 Addict

    It's normal behavior. You must use choke to start but then you get it off as quickly as you can without killing the motor.
  18. Jamps

    Jamps XS400 Member

    I meant that during the first cold startup I couldn’t use any choke. But maybe the garage was warm enough that the bike wasn’t that cold?

    Also, do you know the size of the rear brake bleeder screw on the 79? I can’t find the info in either my owners manual nor the service manual.
  19. amc49

    amc49 XS400 Addict

    You won't find much of anything on bleeder screw sizes, you simply have to compare threads until you find out what you have.

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